# MPC Seminar

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== Previous Seminar talks == | == Previous Seminar talks == | ||

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* [[MathCS Seminar 2016]] | * [[MathCS Seminar 2016]] |

## Revision as of 16:39, 15 January 2019

This is the homepage of the Chapman University Mathematics, Physics, and Computation Seminars

*Seminar Organizers:* Mihaela Vajiac and Justin Dressel

## Fall 2018

The seminar talks are held in Keck Center for Science and Engineering, KC 171 (Center St. Orange, CA 92866, intersection of Center St. And Sycamore St.). Sometimes there will be a change of venue and the announcement will reflect this change.

See [http://www.chapman.edu/discover/maps-directions/index.aspx Maps and directions], Keck Center is Building 28 on the Campus Map [https://www.chapman.edu/about/_files/maps-and-directions/current-maps/campus-map.pdf Campus map]

### Thursday, December 6th 2018 at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Bogdan Suceava, CSUF **

*Title:* ** Strictly Convex Hypersurfaces Satisfying Weingarten-Type Inequalities **

*Abstract: * Linear Weingarten surfaces in three-dimensional ambient space satisfy a relation between mean curvature and Gaussian
curvature: aH^2+bK=c. We investigate whether for hypersurfaces invariant to inversions of dimensions 3, 4, and 5, there are
curvature inequalities similar to the classical Weingarten condition. We also consider the globalization of these pointwise
inequalities. This question is suggested by the investigations of Bang-Yen Chen’s fundamental inequalities, as we reflect
on the geometric interpretations of these relations.Additionally, we plan to discuss other related inequalities, investigated in recent
works written with Mihaela Vajiac, Nicholas Brubaker, and Leonard Giugiuc, respectively.

### Friday, November 30th 2018 at 2:00pm, in Keck 171, tea and cookies at 1:30pm in Keck 370

#### *Speaker:* ** Dr. Apostolos Tzimoulis, Chapman University postdoc **

*Title:* ** Proof theory and algebraic semantics for predicate logics **

*Abstract: * I will start with recasting classical first-order logic in an algebraic and proof-theoretic framework based on Lawvere's theory of hyperdoctrines. Then I will discuss the problem of obtaining general semantics for predicate non-classical logics, provide some examples, and argue that algebraic and proof-theoretic insight can help us understand better and solve this problem.

### Thursday, November 29th 2018 at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Sabine Hossenfelder (Frankfurt Institute for Advanced Studies)**

*Title:* ** Do women get fewer citations than men? **

*Abstract: * I will talk about the results of a citation analysis on
publication data from the arXiv and inspire in which we explored gender
differences. I will further explain how we can use bibliometric analysis
to improve the efficiency of knowledge discovery.

There is also a public talk at 7pm, See Public Talk, Argyros Forum, 7pm

### Conference: Monday to Friday, November 12th to November 16th in Sandhu Conference Center

#### *Speaker:* ** Advances in operator theory with applications to mathematical physics **

*CONFERENCE:* ** Advances in operator theory with applications to mathematical physics **

*Abstract: * For a complete schedule, and a list of abstracts, see: Conference Webpage.

### Monday, November 5th 2018 at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Uwe Kahler, Universidade de Aveiro, **

*Title:* ** Curvature detection using Taylorlets **

*Abstract: * The problem in detection of nodules in medical images consists of two parts: the detection of edges and the detection of curvature. For the detection of edges as elements of the wavefront set of an image shearlets appeared in the last decade as the principal approach based on approximation. But elements of the wavefront set have a problem in the sense that they are singularities with prescribed direction, but not prescribed curvature. To overcome this problem higher order shearlets, so-called Taylorlets were introduced. While we will discuss them in this talk we will also point out and discuss a principal mathematical problem arising in their application: the problem of construction of a Schwartz function with infinitely many generalized vanishing moments. We will show that Meyer’s frequency-based approach does not fit this case and provide a space-based method for its generation.

### Thursday, November 1st 2018 at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Roman Buniy, Chapman University **

*Title:* ** Tripartite entanglement of qudits **

*Abstract: * We provide an in-depth study of tripartite entanglement of qudits. We start with a short review of tripartite entanglement invariants, prove a theorem about the complete list of all allowed values of three (out of
the total of four) such invariants, and give several bounds on the
allowed values of the fourth invariant. After introducing several
operations on entangled states (that allow us to build new states from
old states) and deriving general properties pertaining to their
invariants, we arrive at the decomposition theorem as one of our main
results. The theorem relates the algebraic invariants of any
entanglement class with the invariants of its corresponding components
in each of its direct sum decompositions. This naturally leads to the
definition of reducible and irreducible entanglement classes. We
explicitly compute algebraic invariants for several families of
irreducible classes and show how the decomposition theorem allows
computations of invariants for compounded classes to be carried out
efficiently. This theorem allows us to compute the invariants for the
infinite number of entanglement classes constructed from irreducible
components. We proceed with the complete list of the entanglement
classes for three qutrits with decompositions of each class into
irreducible components, and provide a visual guide to interrelations of
these decompositions. We conclude with numerous examples of building
classes for higher spin qudits.

### Friday, October 26th at 3:00pm, in Keck 171, tea and cookies at 2:30pm in Keck 370

#### *Speaker:* ** Dr. Askery Canabarro, Federal University of Alagoas - BRAZIL **

*Title:* ** Statistical and Machine Learning for physicists, but not just Physics (part 2) **

*Abstract: * Machine Learning has become one of the most exciting areas of modern research and application. In these talks we provide an introduction to the core concepts and tools of machine learning in a way easily understood and intuitive to physicists. The review begins by covering fundamental concepts in ML and modern statistics such as overfitting, regularization, and generalization before moving on to more advanced topics in both supervised and unsupervised learning, for instance: ensemble deep learning, auto ML and so on. We illustrate the ideas with problems we are currently involved in.

Part 2 of a series of 2 talks.

### Thursday, October 25th at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Askery Canabarro, Federal University of Alagoas - BRAZIL **

*Title:* ** Statistical and Machine Learning for physicists (part 1) **

*Abstract: * Machine Learning has become one of the most exciting areas of modern research and application. In these talks we provide an introduction to the core concepts and tools of machine learning in a way easily understood and intuitive to physicists. The review begins by covering fundamental concepts in ML and modern statistics such as overfitting, regularization, and generalization before moving on to more advanced topics in both supervised and unsupervised learning, for instance: ensemble deep learning, auto ML and so on. We illustrate the ideas with problems we are currently involved in.

Part 1 of a series of 2 talks.

### Friday, October 19th at 1:00pm, in Keck 171, tea and cookies at 2:00pm in Keck 370

#### *Speaker:* ** Dr. Erik Linstead, Chapman University **

*Title:* ** A Convoluted Talk **

*Abstract: * Convolutional neural networks (CNNs) represent the current state-of-the-art in machine learning for computer vision. In this talk we will discuss some interesting applications of CNNs to non-traditional domains, as well as explore what happens to CNNs when we ignore computational efficiency to more closely align with neural physiology.

### Thursday, October 18th at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Sandu Popescu, IQS, Chapman University **

*Title:* ** Dynamical quantum non-locality **

*Abstract: * During the 50 years since its discovery, the Aharonov–Bohm effect has had a significant impact on the development of physics. Its arguably deepest implication, however, has been virtually ignored.

Next year will be the 60th anniversary of the discovery of the Aharonov–Bohm (AB) effect, one of the most surprising and quintessential effects in quantum mechanics. Since its discovery in 1959, the AB effect has made a significant impact on the development of physics. It has been generalized in a variety of directions — from a rather straightforward dual effect such as the Aharonov–Casher effect, to the celebrated Berry phase, to non-Abelian gauge theories, to Wilson loops, to anyons. During these past 60 years the impact of the AB effect has been significant indeed.

And during all these past 60 years, what I believe to be by far the deepest implication of the AB effect (discovered by Yakir Aharonov and described in his Tel Aviv University lecture notes and elsewhere) has been virtually ignored. It is an implication that transcends the specific context from which it originates, and goes directly to the very core of quantum physics: the quantum equations of motion are non-local. Without appreciating this fact, it is safe to say that no real understanding of the nature of quantum mechanics is possible.

### Thursday, October 4th at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Justin Dressel, Chapman University **

*Title:* ** Strengthening weak measurements for qubit tomography and multitime correlators **

*Abstract: * We re-examine the measurement strength needed to perform two recent quantum information tasks with qubits: state tomography using weak values, and determining multitime correlators. Traditionally these protocols have required weak measurements that are minimally disturbing, meaning that the coupling between an investigated quantum system and a measurement device has no appreciable influence on the evolution of the system. We show that the weakness of the interaction is not in fact necessary when measuring qubits. For the case of state tomography, we report an experiment performed with neutron matter-waves that extends the notion of generalized eigenvalues for the neutron's path system to allow the exact determination of weak values using both strong and weak interactions. Experimental evidence is given that strong interactions outperform weak ones both for precision and accuracy. For the case of obtaining multitime correlators, we show a method that uses sequential generalized measurements. Specifically, if a correlator can be expressed as an average of nested (anti)commutators of operators that square to the identity, then that correlator can be determined exactly from the average of a measurement sequence of arbitrary strength. We show that both two-point and four-point (out-of-time-ordered) correlators belong to this useful class of qubit correlators.

### Thursday, September 27th at 4:15pm, in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Dr. Matthew Leifer, Chapman University**

*Title:* ** Fine Tunings and the Nature of Quantum Reality **

*Abstract: * Despite many years of research, there is still no universally agreed upon realist interpretation of quantum theory. In this talk, I argue that the main problem is to deal with the fine-tunings implied by no-go theorems about realist approaches to quantum theory, such as Bell’s theorem. We should seek to either eliminate these fine tunings or explain them as emergent. I will give an overview of the various fine-tunings that exist in quantum theory, due to nonlocality, contextuality, lack of time-symmetry, and results on the reality of the quantum state. I will explain how we can quantify each fine tuning, and exploit them in quantum information processing tasks. If time permits, I will outline two approaches to solve the fine-tuning problem based on block universe models with retrocausality and many-worlds.

### Tuesday, September 18th at 4:15pm in Keck 171, tea and cookies at 3:45pm in Keck 370

#### *Speaker:* ** Professor H. Turgay Kaptanoglu, Department of Mathematics, Bilkent University, Ankara **

*Title:* ** Singular Integral Operators With Bergman-Besov Kernels on the ball **

*Abstract: * Although the boundedness of the Bergman-Besov projection operators from Lebesgue classes onto Bergman-Besov spaces has been studied for several decades, the study of the boundedness of the same operators as singular integral operators between different Lebesgue classes are rather new. Some initial work has recently been done by Cheng, Fang, Wang, Yu for the weighted Bergman operator on the unit disc and by Cheng, Hou, Liu for the Drury-Arveson operator. Also Zhao has investigated certain sub-cases of the same problem as Bergman projections. The methods they employ are sporadic and specific to the particular cases they are interested in.

### The 4th SYSMICS Workshop: Friday-Monday, September 14-17, in Sandhu Conference Center D1

#### *Speaker:* ** The 4th SYSMICS Workshop **

*Title:* ** Topic of the workshop: "Duality in Algebra and Logic” **

*Abstract: * Workshop Webpage: http://math.chapman.edu/~jipsen/sysmics/

### Friday, August 31st at 3:30pm, in Beckman 404

#### *Speaker:* ** Dr. Philip Mannheim, Professor of Physics, University of Connecticut **

*Title:* ** The Crisis in Fundamental Physics **

*Abstract: * Cosmology deals with the the astrophysical macroscopic universe on large
scales while fundamental physics deals with the particle physics
microscopic universe on small ones. Recently it has become apparent that
large and small scale physics are actually intertwined leading to an
astro-particle picture of the universe. At the present time this picture
has achieved great success, but at the same time it has led to many open
questions and challenges, challenges which threaten to potentially
undermine the entire picture. These challenges include dark matter, dark
energy, the cosmological constant problem, quantum gravity, the status of
supersymmetry, the multiverse picture, extra space-time dimensions, and the nature of the Higgs boson. In this talk we review these issues and suggest that their resolution would require a paradigm shift in our view of the universe.

### Friday, August 31st at 1:00pm, Keck 171, lunch with the speaker in the Faculty Club at noon

#### *Speaker:* ** Dr. Philip Mannheim, Professor of Physics, University of Connecticut **

*Title:* ** Why physicists are interested in differential geometry **

*Abstract: * Ever since Einstein's development of gravity theory, general relativity and differential geometry have been central components of physics research and of our understanding of the universe. Of special interest is how gravity can interface with the other fundamental forces, the nuclear force, the weak force, and especially the electromagnetic force. In this talk we describe some of the motivation and central achievements for general relativity, and discuss some proposed generalizations of it such as torsion and Weyl geometry that might lead to a purely geometric unification of the fundamental forces.

### Thursday, August 30th at 4:00pm, Keck 171, tea and cookies at 3:30pm in Keck 370

#### *Speaker:* ** Dr. Philip Mannheim, Professor of Physics, University of Connecticut **

*Title:* ** Quantum Conformal Gravity **

*Abstract: * Conformal symmetry is a natural symmetry in physics since it is the full symmetry of the light cone. If all particles are to get their masses by symmetry breaking then conformal symmetry is the symmetry of the unbroken Lagrangian. Like Yang-Mills theories conformal symmetry has a local extension, namely conformal gravity, a pure metric-based candidate alternative to the non-conformal invariant standard Newton-Einstein theory of gravity. With its dimensionless coupling constant quantum conformal gravity is power counting renormalizable. Since its equations of motion are fourth-order derivative equations conformal gravity has long been thought to possess unacceptable ghost states of negative norm that would violate unitarity. However on constructing the quantum Hilbert space Bender and Mannheim found that this not to be the case. Conformal gravity is thus offered as a completely consistent and unitary quantum theory of gravity, one that requires neither the extra dimensions nor the supersymmetry of string theory. As formulated via local conformal invariance there is no intrinsic classical gravity, with gravity instead being intrinsically quantum-mechanical, with the observed classical gravity being output rather than input. The contribution of the graviton loops of conformal gravity enables conformal gravity to solve the cosmological constant problem. Like Yang-Mills the potential of conformal gravity contains both a Newtonian term and a linear potential. Together with a quadratic potential that the theory also contains conformal gravity is able to explain the systematics of galactic rotation curves without any need for galactic dark matter. Since all mass is to be dynamical there cannot be a fundamental double-well Higgs potential in the theory. Instead, the Higgs boson is generated dynamically, with the hierarchy problem then being solved.

### Thursday, August 23rd at 4:00pm, Keck 171, tea and cookies at 3:30pm in Keck 370

#### *Speaker:* ** Dr. Gunduz Caginalp, Professor of Mathematics, University of Pittsburgh**

*Title:* ** Volatility Maxima as a Forecaster of Trading Price Extrema **

*Abstract: * This is joint work with Carey Caginalp. The relationship between price volatility and a market extremum is examined using a fundamental economics model of supply and demand. By examining randomness through a microeconomic setting, we obtain the implications of randomness in the supply and demand, rather than assuming that price has randomness on an empirical basis. Within a very general setting the volatility has a maximum that precedes the extremum of the price. A key issue is that randomness arises from the supply and demand, and the variance in the stochastic differential equation governing the logarithm of price must reflect this. Analogous results are obtained by further assuming that the supply and demand are dependent on the deviation from fundamental value of the asset.

## Spring 2018

The seminar talks are in Von Neumann Hall VN 116 (545 W Palm Ave corner of W Palm Ave and railroad, Orange, CA 92866). Sometimes there will be a change of venue and the announcement will reflect this change.

See [http://www.chapman.edu/discover/maps-directions/index.aspx Maps and directions], Von Neumann Hall is Building 48 on the Campus Map [https://www.chapman.edu/about/_files/maps-and-directions/current-maps/campus-map.pdf Campus map]

### Friday, May 11th at 3:00pm, Von Neumann Hall, tea and cookies at 2:30pm

#### *Speaker:* ** Dr. Nadia Ahmed, Saddleback**

*Title:* ** Consumer-centric Residential Demand Side Management **

*Abstract: * Energy Management Systems (EMS) are mainly price driven with minimal consumer interaction. To improve the effectiveness of EMS in the context of demand response, an alternative EMS control framework driven by resident behavior patterns is developed. Using hidden Markov modeling techniques, the EMS detects consumer behavior from real-time aggregate consumption and a pre-built dictionary of reference models. These models capture variations in consumer habits as a function of daily living activity sequence. Following a training period, the system identifies the best fit model which is used to estimate the current state of the resident. When a request to activate a time-shiftable appliance is made, the control agent compares grid signals, user convenience constraints, and the current consumer state estimate to predict the likelihood that the future aggregate load exceeds a consumption threshold during the operating cycle of the requested device. Based on the outcome, the control agent initiates or defers the activation request. In an extension of this work, a battery health conscious stochastic dynamic programming control framework is introduced as part of a greater cyber physical system which incorporates the harvesting unit, the storage unit, the residential load profile, the weather, the weather forecast, the utility, and consumer preferences into a unified Markov decision process.

### IQS Live Podcast, Monday, April 16th at 6:00pm, 1888 Center, 115 North Orange Street

#### *Speaker:* ** Adam Becker**

*Title:* ** What Is Real? The Unfinished Quest for the Meaning of Quantum Physics**

*Abstract: * IQS Live podcast recording and book signing with Adam Becker, author of:

"What Is Real? The Unfinished Quest for the Meaning of Quantum Physics”

Monday April 16 6pm-8pm 1888 Center, 115 North Orange Street, Orange, CA 92866

Produced in partnership with the Institute for Quantum Studies, Chapman University

Organized by IQS. Free admission, but seating is limited so you have to RSVP at the following link:
Event Registration

### Friday, April 13th at 3:30pm, Von Neumann Hall, tea and cookies at 3:00pm

#### *Speaker:* ** Dr. Jose Raul Gonzalez Alonso, Chapman University**

*Title:* ** Quantum Chaos, Information Scrambling, and Out-of-time-ordered Correlators **

*Abstract: * Out-of-time-ordered-correlators (OTOCs) have emerged as a useful tool to study quantum chaos and the scrambling and delocalization of information in many-body systems. While challenging, their experimental measurement has been achieved in NMR, trapped ion, and superconducting systems. In this talk, I will review the different open problems at the intersection of quantum chaos, information scrambling, and OTOCs and the recent progress in solving them.

### Friday, April 6th Sixth annual Computational and Data Sciences Graduate Conference

#### *Speaker:* ** Chapman University Graduate Students, 9:15am - 4:30pm, Argyros Forum 209ABC**

*Title:* ** Sixth annual Computational and Data Sciences Graduate Conference**

*Abstract: * Various

### Friday, March 30th at 3:00pm, Von Neumann Hall

#### *Speaker:* ** Kai-Wen Tu, Chapman University**

*Title:* ** Fourier Transform and Signal Processing Application with a SAR Imaging Example**

*Abstract: * In solving heat-flow problems Fourier found that a periodic function can be represented by an infinite series of sinusoidal functions. Generalization from Fourier Series to Fourier Transform and its discrete form, the Discrete Fourier Transform (DFT) will be discussed briefly. Development of a computationally efficient algorithm FFT (Fast Fourier Transform) for computing DFT will be described with MATLAB illustration.
The second part of the talk will focus on a specific signal processing application using FFT. An overview of imaging radar systems with conventional aperture as well as with synthetic aperture (SAR) will be given. Image resolution will be shown to be related to pulse compression and synthetic array processing as the antenna beam creates a footprint with the continuing illumination of a designated spot. Image formation of the Spotlight imaging mode encompassing signal data collection, motion compensation, data sampling, range dechirp, azimuth compression, polar interpolation, 2-D FFT, phase correction, and pixel magnitude encoding will be presented.

### Tuesday, March 20th at 3:00pm, Von Neumann Hall

#### *Speaker:* ** Mic Detlefsen, University of Notre Dame **

*Title:* ** Some Elements of Hilbert’s Formalism **

*Abstract: * The aim of this talk is to describe and consider the significance of a certain element of Hilbert¹s formalist viewpoint that I call its descriptive or observational element. This element played an important role in shaping Hilbert¹s distinctive approach to the consistency problem for arithmetic (and to other consistency problems). It seems not to have been generally well recognized and appreciated.

### Friday, March 16th at 3:00pm, Von Neumann Hall

#### *Speaker:* ** Lorenzo Catani, UCL **

*Title:* ** Csirelson’s bounds as a refinement of Landauer’s principle **

*Abstract: * I will present a simple single qudit protocol that computes a non-linear function. It consists of a system in a fixed state, two gates controlled by classical dits (d-level systems) and a fixed measurement. The goal is to choose gates to optimise the average probability over all input combinations of dits to obtain the target non-linear function as output.

I will show that any strategy in the single-qudit protocol can be mapped to a strategy in a two qudits CHSH game, thus obtaining the known classical Bell bounds for the strategies that only involve classical reversible computation or quantum stabiliser computation, and Csirelson’s bounds for general quantum strategies. Since the single qudit protocol restricts the degrees of freedom to gates only, we analyse the bounds obtained in light of Landauer’s principle, showing that there is a trade-off in entropic cost versus increased success probability. The single qubit computation can perform better than the reversible bit computation, but it cannot achieve the performance of the irreversible computation. In this sense the protocol acts as an irreversibility witness. In the case of systems of dimension two (bits and qubits) these results have a clear geometric interpretation in the corresponding state spaces.

I will briefly discuss how our scheme also acts as a dimensional witness and I will conclude with some comments on the sources of non-classicality present in the current protocol since non-locality and contextuality (in its standard notions) are not present.

### Friday, March 9th at 3:00pm, Von Neumann Hall

#### *Speaker:* ** Dr. Carey Caginalp, University of Pittsburgh **

*Title:* ** Supply, Demand, Volatility and Fat Tails **

*Abstract: * The classical equations of mathematical finance involve basic assumptions that are convenient mathematically and are essentially a particular limit of the underlying market phenomena. The assumptions involve infinite capital for arbitrage and independent Gaussian increments in relative price change. Among the consequences are an exponential decay in large deviations of relative price and volatility that is essentially constant in time. We use a basic supply/demand model to explain the fat tails phenomena based on endogenous reasons. The bubble in cryptocurrencies can also be explained in terms of this approach in which the liquidity price, namely, cash available for investing in a particular asset divided by the number of units available. Current work is focused on demonstrating that the extrema in price are accompanied by extrema in volatility.
(Research in collaboration with Dr. Carey Caginalp)

### IQS Workshop: Saturday, March 3rd, Argyros Forum 212

#### *Speaker:* ** Quantum Simulation and Quantum Walks Workshop **

*Title:* ** Quantum Simulation and Quantum Walks Workshop **

*Abstract: * Organized by IQS. For registration to this event please follow the link: Event Registration.

### IQS Workshop: Thursday-Friday, March 1st and 2nd, Beckman Hall 404

#### *Speaker:* ** AAV Anniversary Conference - Celebrating 30 Years of Weak Values **

*Title:* ** AAV Anniversary Conference - Celebrating 30 Years of Weak Values **

*Abstract: * Organized by IQS. For registration to this event please follow the link: Event Registration.

### Friday, February 23rd at 3:00pm, Von Neumann Hall

#### *Speaker:* ** Dr. Ken Wharton, San Jose State **

*Title:* ** Spacetime-Based Retrocausal Models **

*Abstract: * Ordinary quantum states grow exponentially with particle number, and cannot exist as a function on ordinary spacetime. But when retrocausal models are considered, the reason for this exponential growth disappears, raising the exciting prospect of some ontic description of quantum phenomena that does exist in spacetime. (In such models the spacetime-based ontic parameters need only work for the actual future measurement setting, not all possible counterfactual settings.) I will give a detailed example of such a model, which can properly account for all maximally-entangled two-qubit states. The key is an "all at once" analysis of the histories, rather than a dynamical evolution of instantaneous states. Intriguingly, the model naturally supplies a novel alternate interpretation of Weak Values.

### Thursday, February 22nd at 4:00pm, Von Neumann Hall

#### *Speaker:* ** Adam Becker, Science Writer **

*Title:* ** Myths about the history of the de Broglie-Bohm interpretation: setting the record straight **

*Abstract: * Misconceptions about the de Broglie-Bohm interpretation of quantum mechanics appeared immediately at its first public presentation by de Broglie at Solvay in 1927. It took many years for those misconceptions to fall away. Today, we finally have a good understanding of the theory (or at least a better understanding), but there are still many common misconceptions about its history. What were the nature of the objections to de Broglie's version of the interpretation at Solvay? Why did de Broglie abandon it? What prompted Bohm to look for a new interpretation 25 years later? How were Bohm's ideas received by his contemporaries? And why did Bohm himself ultimately abandon his own ideas for another quarter of a century? There are "standard" answers to these questions, most of which are simply myths. For example, Pauli did not stump de Broglie at Solvay, Oppenheimer was generally kind to Bohm during his time on the blacklist, and Bohm's ideas were not simply ignored or dismissed out of hand by his contemporaries. In my talk, I will discuss the origins of these myths, and the far more complicated and surprising historical truths that they obscure.

### Friday, February 16th at 3:00pm, Von Neumann Hall

#### *Speaker:* ** Eli Levenson-Falk, USC **

*Title:* ** Fleas on Schrödinger's Cat: Quasiparticles in Superconducting Quantum Circuits **

*Abstract: * Superconducting electrical circuits can be used for quantum computing, quantum simulation, ultra-low-noise amplification, and precision sensing. However, quasiparticles--electron-like single-particle excitations of the superconducting condensate--can cause loss and noise, limiting the performance of these devices. The generation mechanisms, behavior, and annihilation channels of these quasiparticles are still poorly understood, hindering efforts to eliminate them from circuits. I will review the evidence for different quasiparticle models, show measurements using Andreev bound states as quasiparticle traps, and discuss future experiments that will determine the best ways to mitigate the harmful effects of quasiparticles.

### Friday, February 9th at 4:00pm, Beckman Hall 105

#### *Speaker:* ** Dr. J.H. Eberly, Department of Physics and Astronomy, Center for Coherence and Quantum Optics, University of Rochester **

*Title:* ** Hidden Coherences and Complementarity **

*Abstract: * Interference, duality, polarization, coherence and entanglement are a partial list of notions that belong to both quantum physics and classical optics. It has been our recent goal to bring quantum-classical links into wider view and to indicate directions in which forthcoming and future work may be able to promote discussion and lead to a more unified understanding. A starting point has often been Niels Bohr's pronouncements and explanations of complementarity, as a way to come to grips with de Broglie's duality. Related debates have engaged and challenged philosophers as well as physicists for almost a century. Complemenn-classical world's mysterious quantum features. Disputed analyses and unresolved conflicts are still debated. It seems to have escaped notice that a key element in Bohr's own defining summary has never been captured in assessments to date. We will report what we believe to be the first description of complementarity that is quantitatively complete, along with experimental evidence of completeness.

### Friday, February 9th, at 2:00pm in Hashinger 150 (Irvine Lecture Hall)

#### *Speaker:* ** Dr. Cumrun Vafa, Harvard University **

*Title:* ** Fundamental Lessons From String Theory **

*Abstract: * String theory has been developed for more than 40 years
now but it seems that we are still far from its final formulation.
Nevertheless, I explain some of the highlights of what we have learned
from string theory and how it revolutionizes many of the fundamental
principles of physics.

### Thursday, February 8th, at 7:00pm in Beckman Hall 404

#### *Speaker:* ** Dr. Cumrun Vafa, Harvard University **

*Title:* ** Physics and Geometry **

*Abstract: * This talk reviews the deep historical connections between geometry
and physics. In modern times, the extra dimensions of string theory has provided a new
opportunity for enhancing this interplay which will be illustrated by concrete examples.

### Monday, February 5th at 4:00pm, Von Neumann Hall

#### *Speaker:* ** Dr. Ales Pultr, Charles University, Prague **

*Title:* ** Point-free topology and some of its merits **

*Abstract: * Point-free thinking, example. Points vs. (realistic) places.
A glimpse of history: Synthetic and analytic geometry; classical topology as a generalized geometry is the analytic version of such a generalization. De- velopment starting in late 30ties and 40ties, how the point-free ideas connect with the classical ones (Hausdorff, Kuratowski, Caratheodory, Freudenthal). The break in the late fifties.
Definition of a locale (frame). Basic concepts and how one works with them.
One obtains a broader range of spaces and every generalization calls for justification. This will be done by discussing the following legitimate ques- tions.
(1) Is the broader range of spaces desirable? Do we get in some sense a better theory and when?
(2) Is the algebraic technique appropriate, does it not obscure the geomet- ric content?
(3) Do we not lose to much information when abolishing points?
We will start by briefly answering question (3) and then go to (1) and (2) presenting examples of results that are nicer, or cannot hold in the classical context at all. In particular we will emphasize the constructive aspects (facts working without choice principles, such as compactification, completion, or Stone duality - the last is so simple that it can serve also as an example of the advantage of the algebraic techniques).
Note of the role of point-free topology in logic and theoretical computer science.

### Monday, January 29th at 3:00pm, Von Neumann Hall, third session of the OCIE-HPML seminar

#### *Speaker:* **Dr. Jamie Tappenden (USC) **

*Title:* ** Frege, Carl Snell and Romanticism; Fruitful Concepts and the 'Organic/Mechanical' Distinction **

*Abstract: * A surprisingly neglected figure in Frege scholarship is the man Frege describes (with praise that is very rare for Frege) as his "revered teacher", the Jena physics and mathematics professor Carl Snell. It turns out that there is more of interest to say about Snell than can fit into one talk, so I'll restrict attention here to just this aspect of his thought: the role of the concept of "organic", and a contrast with "mechanical". Snell turns out to have been a philosophical Romantic, influenced by Schelling and Goethe, and Kant's Critique of Judgement. In Frege's environment, the "organic/mechanical" contrast, understood in a distinctively Romantic fashion, had reached the status of "accepted, recognized cliché". More generally, Frege's environment was more saturated with what we now call ``Continental philosophy" than we might expect. This context-setting has a payoff for our reading of Frege's texts: many expressions and turns of phrase in Frege that have been regarded as vague, throwaway metaphors turn out to be literal references to ideas that would have been salient among the people in Frege spent time with day-to-day. In particular, this is true of Frege's account of "extending knowledge" via "fruitful concepts" and his rejection of the idea that logic and mathematics can be done "mechanically" (as with Jevons' logic machines, or Fischer's "aggregative mechanical thought"). When Frege appealed to "organic connection" and speaks of fruitful concepts as containing conclusions "like a plant in its seeds", he would have expected his apparent metaphors to have been understood in a very specific way, as alluding to a recognized contrast between "organic" and "mechanical" connection that was applied by Snell and those close to him not only to distinctions between biological and physical reasoning but also to distinctions of types of reasoning in arithmetic and geometry.

### Monday, January 29th at 4:00pm (Beckman Hall 404)

#### *Speaker:* ** Peter Coffee, Vice President for Strategic Research at salesforce.com **

*Title:* ** The Future That's Already Happened: Fundamental Forces of Change**

*Abstract: * There are two ways to talk about "the future." One involves making predictions of what might happen. The other, much less speculative, solves present-day equations for a future value of time. Today, the second approach can make use of observable facts about connection, collaboration, acceleration, and introduction of machine intelligence ("Ex Machination") into devices and processes -- to give us a crisp and compelling picture of what otherwise might seem wild-eyed visions.

For registration to this event please follow the link: Event Registration.

## Fall 2017

The seminar talks are in Von Neumann Hall VN 116 (545 W Palm Ave corner of W Palm Ave and railroad, Orange, CA 92866). Sometimes there will be a change of venue and the announcement will reflect this change.

See [http://www.chapman.edu/discover/maps-directions/index.aspx Maps and directions], Von Neumann Hall is Building 48 on the Campus Map [https://www.chapman.edu/about/_files/maps-and-directions/current-maps/campus-map.pdf Campus map]

### Friday, December 15th at 4:00pm (Argyros Forum 212)

#### *Speaker:* ** Dr. Andrew Jordan from University of Rochester, and Kater Murch from Washington University in St. Louis **

*Title:* ** The arrow of time in quantum mechanics**

*Abstract: * The question of why we perceive time moving from past to future is perplexing, especially in light of the fact that microscopic laws of motion are the same running forward or backwards in time. Some have thought that the answer to this puzzle may lay in quantum wavefunction collapse. We will discuss how recent experiments have shown that quantum measurement may not be as irreversible as commonly thought, and discuss deep questions relating to the flow of time and quantum physics. We will approach the topic from three points of view, that of the experimentalist, the quantum theorist, and the philosopher.

### Thursday, December 14th at 4:00pm (Argyros Forum 212)

#### *Speaker:* ** Dr. Kater Murch from Washington University in St. Louis **

*Title:* ** Measurement and control in superconducting qubits: from the quantum Zeno effect to quantum enhanced metrology **

*Abstract: * The quantum Zeno effect is a feature of measurement-driven quantum evolution where frequent measurement inhibits the decay of a quantum state. We will explore how the opposite effect; the anti-Zeno effect - where frequent measurement accelerates decay - can also emerge from frequent measurement. The emergence of one effect or the other elucidates the nature of quantum measurement and the role measurement plays in controlling quantum evolution. In a second experiment, we investigate how control over a single qubit can be used achieve a quantum speedup in the precision of frequency measurements, demonstrating a frequency sensitivity that improves as 1/T^2, where T is the duration of the experiment.

### Thursday, December 14th at 1:00pm (Argyros Forum 212)

#### *Speaker:* ** Dr. Alyssa Ney from UC Davis**

*Title:* ** Physics and Fundamentality **

*Abstract: * What justifies the allocation of funding to research in physics when many would argue research in the life and social sciences may have more immediate impact in transforming our world for the better? Many of the best justifications for such spending depend on the claim that physics enjoys a kind of special status vis-a-vis the other sciences, that physics or at least some branches of physics exhibit a form of fundamentality. The goal of this paper is to articulate a conception of fundamentality that can support such justifications. I argue that traditional conceptions of fundamentality in terms of dynamical or ontic completeness rest on mistaken assumptions about the nature and scope of physical explanations.

### Monday, December 11th at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* ** Dr. Gabriel Uzquiano (USC)**

*Title:* ** Cantorian arguments and the limits of thought **

*Abstract: * Cantor’s theorem has often been thought to play a central role in Kaplan’s paradox for possible worlds semantics for intensional logic. Though we argue that Cantorian reasoning doesn't ultimately reach at the root of the problem, we suggest that some versions of the theorem may in fact be used as a heuristic for arriving at more informative results in the vicinity of Kaplan’s observation.

### Friday, December 1st at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* **Sarah Alexander and Nadiya Upegui, under the supervision of Prof. Peter Jipsen, Chapman University**

*Title:* ** Partial Algebras and their Applications in Generalizations of Effect Algebras **

*Abstract: * A partial algebra is an algebra where at least one of its operations is partial. Like total algebras, partial algebras have their own concepts of homomorphisms, subalgebras, products, and congruences that account for partiality. An effect algebra is a partial algebra with a partial binary operation + that satisfies associativity and commutativity and induces a natural partial order with a bottom element 0 and a top element 1. It also contains a total unary operation ’, behaving in such a way that for all x there exists an x’ such that x+x’=1. Effect algebras can be generalized or specialized by adding or removing axioms to change their structure. A much more general class related to effect algebras is the class of generalized pseudo-effect algebras (GPEAs). GPEAs maintain associativity but are no longer commutative and need not have a unary operation ’ nor a single maximum element. It can be proven that the existence of the unary operation ’ in effect algebras in conjunction with some of the other axioms implies that + is cancellative and that 0 acts as an identity for +. These results cannot be deduced when working with GPEAs, so these properties are adopted in the GPEA axiomitization. This class of algebras also assumes a weaker notion of commutativity called conjugation. Taking a maximal element and adding it to or removing it from a GPEA creates another GPEA, and this result is the basis for a more efficient version of a Python program used to generate and enumerate these structures. Moreover, studying how changes can be made to the structure of these classes of algebras makes them easier to understand and work with. We describe two such processes, unitization and totalization, which produce involutive residuated partially ordered monoids as the resulting structures.

### Conference: Tuesday to Sunday, November 14th to November 19th in Sandhu Conference Center

==== *Speaker:* **Mathematics, Signal Processing and Linear Systems:**
New Problems and Directions** ====**

*Title:* **Mathematics, Signal Processing and Linear Systems:**
New Problems and Directions

*Abstract: * For directions, schedule, and book of abstracts, see CECHA Webpage: CECHA Webpage, or the Conference Webpage: Conference Webpage

### CECHA Workshop: Monday to Friday, November 6th to November 10th in VN Hall

#### *Speaker:* **Professor David Walnut, GMU**

*Title:* **An Overview of Wavelet Theory,**
With an eye on Superoscillations

*Abstract: * For a schedule, see CECHA Webpage: CECHA Webpage, or the Workshop Webpage: Wavelet Workhsop

### Friday, November 3rd at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* **Dr. Marcy Robertson, Lecturer, School of Mathematics and Statistics, University of Melbourne**

*Title:* ** TBA**

*Abstract: * TBA

Dr. Robertson's Webpage: Dr. Marcy Robertson

### Thursday, November 2nd at 4:00pm (tea and cookies at 3:30pm, in VN)

#### *Speaker:* **Dr. Alain Yger (University of Bordeaux)**

*Title:* ** Transposing (p,q) - Calculus from the Complex to the Real setting, Applications**

*Abstract: * I will discuss in this talk the various presentations of the so-called theory of super (p,q) currents in the real setting (initiated by A. Lagerberg), together the relations it induces between the Fourier and Legendre-Fenchel dualities. Some applications towards number theory will be also discussed. It seems also that such ideas could be explored in other settings than the complex versus real one (for example quaternionic versus complex). I will in particular speak about the work of my student Robert Gualdi about getting closed formulaes for the logarithmic arithmetic height of an algebraic hypersurface in a toric variety; I will, if time permits, present a certain number of tools that could be necessary in order to extend the codimension one result to the higher codimension case.

### Friday, October 27th at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* ** Dr. Ahmed Sebbar, University of Bordeaux **

*Title:* **Harmonic series, Harmonic sums and the Riemann Hypothesis**

*Abstract: * The harmonic series
$$1+\frac{1}{2}+ \frac{1}{3}+\frac{1}{4}+\cdots $$ is one the most known series. It diverges.
We comment on why the series
$ \sum \frac{1}{p} $
(the sum is over all the primes) also diverges, however the sum $ \sum^{'} \frac{1}{n} $ where the sum is over all the integers whose decimal expansion has no nines converges.

In the second part of the talk we comment on a beautiful result of G. Robin (Limoges University) and J. Lagarias (University of Michigan) concerning the harmonic numbers $\displaystyle H_n= 1+\frac{1}{2}+ \frac{1}{3}+\frac{1}{4}+\cdots+ \frac{1}{n} $ saying that if $\displaystyle \sigma_1(n) $ is the sum of the divisors of $n$ and if $\displaystyle \sigma_1(n) \leq e^{H_n} \log H_n +H_n$ then the Riemann hypothesis is true. This is a very elementary formulation of a Millennium Problem.

### Wednesday, October 25th at 2:30pm (Argyros Forum 208)

#### *Speaker:* ** George Csicsery, Visiting Documentary Filmmaker**

*Title:* ** Finding the hook **

*Abstract: * Filmmaker George Csicsery will discuss how he presents mathematics and mathematicians to lay audiences in a society with attention deficit disorder. Excepts from his films “N is a Number: A Portrait of Paul Erdös” (1993), “Julia Robinson and Hilbert’s Tenth Problem” (2008,” “Hard Problems” (2008), “Counting from Infinity” (2015), and “Navajo Math Circles” (2016), will be used to illustrate his main theme: that scientific ideas and math can be smuggled into a story when there is suspense, drama or genuine human interest at the foundation.

### Saturday, October 21st at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* **Mathematical Association of America Meeting**

*Title:* ** MAA Fall 2017 SoCal-Nevada Section Meeting **

*Abstract: * See the MAA Webpage: SoCal-Nevada MAA Webpage

### Friday, October 20th at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* ** Guillaume Jeremie Massas (UCI)**

*Title:* **Constructive representations of Heyting algebras and semantics for Intuitionistic Predicate Logic**

*Abstract: * Model Theory and the theory of Boolean algebras are two fruitful tools for investigating classical logic. Gödel’s completeness theorem and Stone’s representation theorem are regarded as cornerstones of each field respectively. The celebrated Rasiowa-Sikorski lemma allows one to construct term models out of ultrafilters on Boolean algebras, thus bridging the gap between the two: Rasiowa and Sikorski’s original proof relied on Stone’s representation theorem, and their lemma was used to give a purely algebraic proof of Gödel's completeness theorem. However the general methods behind this approach, because of their appeal to ultrafilters, are highly non-constructive.
Over the years, various generalizations of Stone’s theorem, of Gödel’s theorem, and of the Rasiowa-Sikorski lemma have taken either of the two orthogonal directions:

generalizing the results to wider classes of logics and algebras (in particular to intuitionistic logic and Heyting algebras); working under restricted forms of the axiom of choice and providing more constructive proofs. In this talk, I will present how to combine the two programs. I will first provide more constructive versions of the Rasiowa-Sikorski Lemma and constructive representation theorems for distributive lattices and Heyting algebras. I will then combine those two results to define a constructive semantics for intuitionistic predicate logic, and show how it generalizes existing semantics.

### Friday, October 6th at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* ** David Wallace (USC)**

*Title:* **What is orthodox quantum mechanics?**

*Abstract: * What is called ``orthodox* quantum mechanics, as presented in standard foundational discussions, relies on two substantive assumptions --- the projection postulate and the eigenvalue-eigenvector link --- that do not in fact play any part in practical applications of quantum mechanics. I argue for this conclusion on a number of grounds, but primarily on the grounds that the projection postulate fails correctly to account for repeated, continuous and unsharp measurements (all of which are standard in contemporary physics) and that the eigenvalue-eigenvector link implies that virtually all interesting properties are maximally indefinite pretty much always. I present an alternative way of conceptualising quantum mechanics that does a better job of representing quantum mechanics as it is actually used, and in particular that eliminates use of either the projection postulate or the eigenvalue-eigenvector link, and I reformulate the measurement problem within this new presentation of orthodoxy.*

### Friday, September 29th at 3:00pm (tea and cookies at 2:30pm, in VN)

#### *Speaker:* ** Dr. Justin Dressel, Chapman University**

*Title:* ** Watching a quantum system: How to continuously measure a superconducting qubit**

*Abstract: * It has recently become experimentally possible to monitor the energy levels of a superconducting transmon qubit continuously in time using microwave fields. Such measurements weakly perturb the qubit per unit time, lead to a competition between unitary Hamiltonian dynamics and non-unitary collapse dynamics. I review several subtleties about modeling this measurement process, and discuss several recent achievements made in collaboration with the Siddiqi laboratory at UC Berkeley. Topics include simultaneous measurements of multiple non-commuting observables, the active use of the quantum Zeno effect with a moving measurement basis for qubit control, and subtle aspects about the information content contained in the collected stochastic readout.

Bio: Justin Dressel received his Ph.D. in quantum physics from U Rochester in 2013, was a visiting researcher at RIKEN Wako-shi in Saitama, Japan in 2013, and was a postdoctoral scholar at UC Riverside between 2013-2015, after which he started as an Assistant Professor in Physics and Computational Science at Chapman University. He researches quantum information, computing, and foundations, which is a natural intersection point between physics, mathematics, and computer science. His recent research has focused on algebraic approaches to generalized quantum measurements, quantum computation with superconducting transmon quantum bits using circuit quantum electrodynamics, and Clifford algebraic approaches to relativistic field theory. Though the bulk of his work is theoretical in nature, he works closely with experimental teams whenever possible.

### Friday, September 22nd at 2:00pm (tea and cookies at 1:30pm, in VN)

#### *Speaker:* **Dr. Ahmed Sebbar, University of Bordeaux**

*Title:* **Algebraic methods in analytic questions Second Example**

*Abstract: *The talk concerns some arithmetic and algebraic questions behind the paperfolding. One of its main objectives is to study the power series
\begin{equation}\label{new} \xi(z)= \sum_{n\geq 1} s_n z^n,\; \; |z|<1
\end{equation}
where $(s_n)$ is the paperfolding sequence defined by
\[s_{2n}= s_n,\quad s_{2n+1}= (-1)^n, \quad n\in \mathbb{Z}_+ .\]

This sequence arises as follows: A sheet of paper can be folded once right half over left or left half over right. During the talk we explore the dynamics of a continued fraction related to $ \xi(z) $, and also a relation of the problem with the modularity theorem(formerly the Taniyama-Shimura-Weil conjecture).

### Thursday, September 14th at 4:15pm (tea and cookies at 3:45pm, in VN)

#### *Speaker:* **Dr. Ahmed Sebbar, University of Bordeaux**

*Title:* **Algebraic methods in analytic questions First Example**

*Abstract: * For a fixed $x$, we consider the two functions in $h$, analytic near the origin:
\[\phi(h)= \log\left(1+3hx-h^3\right)†= \sum_{n=0}^{\infty} P_n(x) h^n†\]
and
\[\psi(h)= \log\left(1+3h^2x-h^3\right)†= \sum_{n=0}^{\infty} Q_n(x) h^n†\]
with polynomials in $x$, $P_n(x)$ and $Q_n(x)$. We wonder whether there is a relationship between $P_n(x)$ and $Q_n(x)$. The positive answer to this question depends on the peculiarities of the two quadratic extensions $\mathbb{Q}(i) $ and $\mathbb{Q}(\rho), \rho= \frac{-1+i\sqrt{3}}{2} $ and their relation with theory of complex multiplication for elliptic curves (Lemniscatomic and anharmonic cases). We give a brief history of Class Field Theory, Clausen hypergeometric function and the answer to the question. We show that the polynomials $P_n(x)$ and $Q_n(x)$ have some divisibillity propriety, similar to the one for Lucas sequences.

### Thursday, September 7th at 4:15pm (tea and cookies at 3:45pm, in VN)

#### *Speaker:* **Dr. Imanol Mozo Carollo, Chapman University**

*Title:* **On subspaces of pointfree bitopological spaces and their smallest dense subspace**

*Abstract: * With the purpose of finding a Stone duality for bitopological spaces, A. Jung and A. Moshier introduced in the category of d-frames in which objects are structures that comprise two frames, thought of as lattices of open sets, and two relations that connect both frames, as abstractions of the covering and disjointness relation. The aim of this talk is to explore an approach to the notion of parts of a space in this pointfree bitopological setting.

### Friday, September 1st at 5:00pm (tea and cookies at 4:30pm, in VN)

#### *Speaker:* **Dr. Razieh Mohseninia, Sharif University of Technology**

*Title:* **Topological quantum computation and the stability of topological memories**

*Abstract: * Quantum computers are necessary to simulate quantum systems. The fragility of qubits in presence of decoherence and external noise is the biggest obstacle in realizing a quantum computer. To overcome such problems, topological quantum computation has been introduced by Kitaev that combines the main quantum feature of the quantum world, namely, superposition of states, with the robustness of classical bits which is the result of a macroscopic number of very small entities, comprising each bit. In this way, topological features which are robust against local perturbations are used for storing information. It is well-known that the $Z_3$ Kitaev model can be used to perform universal quantum computation. Due to unwanted interactions in the system, perturbations may be added to a possible realization of the system. In the first part of my talk, stability of the $Z_3$ Kitaev model in the presence of external perturbations in the form of Potts interaction is studied. Our study relies on two high-order series expansions based on continuous unitary transformations in the limits of small and large Potts couplings as well as mean-field approximation. Our analysis reveals that the topological phase of the $Z_3$ Kitaev model breaks down to the Potts model through a first-order phase transition. Another example of topological memories is the Topological Color Code, which in 2 dimensions can be used for implementing the Clifford group in a fully topological and transversal manner. In the second part of my talk, I study thermal stability of this model in presence of a thermal bath. The auto-correlation functions of the observables are used as a figure of merit for the thermal stability. I show that all of the observables auto-correlation functions decay exponentially in time. By finding a lower bound on the decay rate, which is a constant independent of the system size, I show that the Topological Color Code is unstable against thermal fluctuations from the bath at finite temperature, even though it is stable at $T=0$ against local quantum perturbations.

## Summer 2017

The seminar talks are in Von Neumann Hall VN 116 (545 W Palm Ave corner of W Palm Ave and railroad, Orange, CA 92866). Sometimes there will be a change of venue and the announcement will reflect this change.

See [http://www.chapman.edu/discover/maps-directions/index.aspx Maps and directions], Von Neumann Hall is Building 38 on the [http://www.chapman.edu/discover/_files/CU_CampusMap2012-13-2.pdf Campus map]

### Wednesday, July 26th at 4:00pm (tea and cookies at 3:30pm, in VN)

#### *Speaker:* **Dr. Angelyn R. Lao, Department of Mathematics, De La Salle University, Philippines**

*Title:* **Systems Approaches in Making Sense of Data and Providing Meaning to Biological Models**

*Abstract: * Systems biology is an interdisciplinary approach that aims at understanding the dynamic interactions between components of biological system. It is also an approach by which biological questions are addressed through integrating experiments in iterative cycles with computational modelling, simulation and theory. This approach is best applied when there is synergistic usage of the models and data. As such that the models established are meaningful and make sense to the collected data. Depending on the types, quality, and amount of data and the purpose of the model, the kind of modeling approaches will also vary. Modelling is not the final goal, but is a tool to increase understanding of the system, to develop more directed experiments and finally allow predictions.
Why model? By modeling, we aim to guide data collection, discover new questions, formulate hypotheses, and reveal simplicity in complexity. There are different ways of modeling. One of the most popular approaches is the use of ordinary differential equations (ODE) to model the interactome among the components of a system. Other modeling approaches include stochastic modeling, Boolean modeling, agent-based modeling and etc.
Systems biology is a cross talk between different disciplines. It requires interdisciplinary collaboration between fields like biology, physics, computer science and engineering, with the goal of having a deeper insight of the functional bases of life.

## Spring 2017

See [http://www.chapman.edu/discover/maps-directions/index.aspx Maps and directions], Von Neumann Hall is Building 38 on the [http://www.chapman.edu/discover/_files/CU_CampusMap2012-13-2.pdf Campus map]

### Friday, May 26th at 2:00pm (tea and cookies at 1:30pm, in AF 212)

#### *Speaker:* **Dr. Eleanor Rieffel, Quantum Artificial Intelligence Laboratory, NASA Ames Research Center**

*Title:* **A NASA Perspective on Quantum Computing: Opportunities and Challenges**

*Abstract: * The success of the abstract model of computation, in terms of bits, logical operations, algorithms, and programming language constructs makes it easy to forget that computation is a physical process. Our cherished notions of computation and information are grounded in classical mechanics, but the physics of our universe is quantum. A natural question to ask is how computation would change if we adopted a quantum mechanical, instead of a classical mechanical, model of computation.
In the early 80s, Richard Feynman, Yuri Manin, and others recognized that certain quantum effect could not be simulated efficiently on conventional computers. This observation led researchers to speculate that perhaps such quantum effect could be used to speed up computation more generally. Slowly, a new picture of computation arose, one that gave rise to a variety of faster algorithms, novel cryptographic mechanisms, and alternative methods of communication.

For most computational problems, however, it is currently unknown whether quantum algorithms can provide an advantage, and if so by how much, or how to design quantum algorithms that realize such advantages. Many of the most challenging computational problems arising in the practical world are tackled today by heuristic algorithms that have not been mathematically proven to outperform other approaches but have been shown to be effective empirically. While quantum heuristic algorithms have been proposed, empirical testing becomes possible only as quantum computation hardware is built. The next decade promises to be exciting emerging hardware makes empirical testing of quantum heuristic algorithms more and more feasible.

In the first part of the talk, I will introduce key concepts underlying quantum computing and correct common misconceptions. In the second half of the talk, I will discuss applications of quantum computing, known advantages and limitations, including work at NASA on quantum heuristics. I will briefly touch on the current state-of-the-art in building quantum computers, quantum error correction and fault tolerance, and the many open research questions that remain.

Bio: Eleanor G. Rieffel leads the Quantum Artificial Intelligence Laboratory
at the NASA Ames Research Center. She joined NASA Ames Research Center in 2012 to work on their expanding quantum computing effort, after working at FXPAL where she performed research in diverse fields including quantum computation, applied cryptography, image-based geometric reconstruction of 3D scenes, bioinformatics, video surveillance, and automated control code generation for modular robotics.
Her research interests include quantum heuristics, evaluation and utilization of near-term quantum hardware, fundamental resources for quantum computation, quantum error suppression, and applications for quantum computing. She received her Ph.D. in mathematics from the University of California, Los Angeles. She is best known for her 2011 book Quantum Computing: A Gentle Introduction with coauthor Wolfgang Polak and published by MIT press.

### Friday, May 19th at 2:00pm (tea and cookies at 1:30pm)

*Title:* **Random variables, entanglement and nonlocality in infinite translation-invariant systems**

*Abstract: * We consider the problem of certifying entanglement and nonlocality in one-dimensional translation-invariant (TI) infinite systems when just averaged near-neighbor correlators are available. Exploiting the triviality of the marginal problem for 1D TI distributions, we arrive at a practical characterization of the near-neighbor density matrices of multi-separable TI quantum states. This allows us, e.g., to identify a family of separable two-qubit states which only admit entangled TI extensions. For nonlocality detection, we show that, when viewed as a vector in R^n, the set of boxes admitting an infinite TI classical extension forms a polytope, i.e., a convex set defined by a finite number of linear inequalities. Using DMRG, we prove that some of these inequalities can be violated by distant parties conducting identical measurements on an infinite TI quantum state. Both our entanglement witnesses and our Bell inequalities can be used to certifyentanglement and nonlocality in large spin chains (namely, finite, and not TI chains) via neutron scattering.

Our attempts at generalizing our results to TI systems in 2D and 3D lead us to the virtually unexplored problem of characterizing the marginal distributions of infinite TI systems in higher dimensions. In this regard, we show that, for random variables which can only take a small number of possible values (namely, bits and trits), the set of nearest (and next-to-nearest) neighbor distributions admitting a 2D TI infinite extension forms a polytope. This allows us to compute exactly the ground state energy per site of any classical nearest-neighbor Ising-type TI Hamiltonian in the infinite square or triangular lattice. Remarkably, some of these results also hold in 3D. In contrast, when the cardinality of the set of possible values grows (but remaining finite), we show that the marginal nearest-neighbor distributions of 2D TI systems are not described by a polytope or even a semi-algebraic set. Moreover, the problem of computing the exact ground state energy per site of arbitrary 2D TI Hamiltonians is undecidable.

### Wednesday, May 17th at 2:30pm (tea and cookies at 2:00pm)

#### *Speaker:* **Prof. Daniel Alpay, Chapman University**

*Title:* **Non-commutative Brownian Motion and a New Class of Topological Algebras**

*Abstract: * We study a family of free stochastic processes whose covariance kernels K may be derived as a transform of a tempered measure σ. These processes arise, for example, in consideration non-commutative analysis involving free probability. Hence our use of semi-circle distributions, as opposed to Gaussians. In this setting we find an orthonormal bases in the corresponding non-commutative L2 of sample-space. We define a stochastic integral for our family of free processes.

Joint work with Palle Jorgensen and Guy Salomon

### Friday, May 12th at 2:00pm (tea and cookies at 1:30pm)

#### *Speaker:* **Prof. Abhijit Banerjee, Krishnath College, Berhampore, Calcutta**

*Title:* **Mathematical Formulations of PT Symmetric Bicomplex Quantum Mechanics**

*Abstract: * With a view to obtaining further insight into the nature of eigenvalues and eigenfunctions of a stationary state one-dimensional Schrodinger equation corresponding to a PT-symmetric bicomplex Hamiltonian H we present the mathematical formulations of an analogous version of the Schrodinger equation. Since in such a setting three different types of conjugates of bicomplex numbers appear, each is found to define, in a natural way, a separate class of time reversal operator. However, the induced parity (P)-time (T)-symmetric models turn out to be mutually incompatible, except for two of them which could be chosen uniquely. The later models are then explored by working within an extended phase space. Applications to the problems of harmonic oscillator and isotonic oscillator are considered and many new interesting properties are uncovered for the new types of PT symmetries.

### Wednesday, May 10th at 1:00pm (tea and cookies at 2:00pm, after the seminar)

#### *Speaker:* **Dr. Purbita Jana, Department of Pure Mathematics, University of Calcutta, India **

*Title:* **Graded Frame and related Mathematical structures**

*Abstract: * In this talk the main focus will be the notion of graded frame and its connection with graded fuzzy topological system, fuzzy topological
space with graded inclusion and fuzzy geometric logic with graded consequence. As a ground work we will first discuss the topic of Topology
via Logic" written by S. Vickers, where the notion of topological system and its usefulness in duality theory as well as study of topological
space via logic is mentioned. Generalizing Vickers's work step by step we will reach to the concept of graded frame, related structures and
their utilities.

### Friday, May 5th at 2:00pm (tea and cookies at 1:30pm) in collaboration with the Philosophy Department

#### *Speaker:* **Prof. Alberto Naibo, Sorbonne**

*Title:* **Harmony, Stability, and Identity: An intensional account in proof-theoretic semantics**

*Abstract: * Proof-theoretic semantics are usually conceived in opposition to truth-theoretic semantics. In truth-theoretic semantics, truth is considered as a primitive (non-analyzed) notion, and meaning is then explained in terms of it. On the other hand, in proof-theoretic semantics, meaning is explained in terms of (our) inferential abilities, and truth is then explained in terms of proofs. In order to avoid any possible trivialization of proof-theoretic semantics — boiling it down to truth-theoretic semantics — an intensional, rather than an extensional approach, should be adopted. In particular, the semantic value of a sentence A should not be defined in terms of the simple existence of a proof of A, but in terms of the way in which A is proved, i.e. in terms of the inferential structure of proof of A. In order to specify this structure some properties are asked to be satisfied. The most known of them is the property of harmony, which corresponds to the reduction of local complexity peaks (detours) in a proof. However, as Dummett claims, this property is “an excessively modest demand”, and it should be complemented by another property, that of stability. It will be shown that this property can be captured by a more fundamental operation, that of expansion, allowing one to generate local complexity riffs within a proof. Even if this operation could seem very natural to add, it will be shown in fact how it is destructive for the intensional account proper to proof-theoretic semantics. In particular, when this operation of expansion is used in presence of negation and identity, it leads to the collapse of the set of proofs of negative and identity sentences, respectively. Finally, the case of identity is analyzed in details in the framework of Martin-Löf’s type theory. It is shown, in particular, that a possible way of avoiding the collapse between identity proofs can be found in the works of M. Hoffman and T. Streicher, where the operation of expansion is lifted from the level of proof-objects to the level of the sentences which speak about these proof-objects.

### Friday, May 5th at 12:00pm (tea and cookies at 1:30pm) in collaboration with the Philosophy Department

#### *Speaker:* **Professor Pierre Wagner, Sorbonne**

*Title:* **The normative character of logic and pluralism**

*Abstract: * Logic is traditionally regarded as normative and the justification of such a view has often been that the laws of logic do not have any descriptive content: they do not describe how we do think but provide prescriptions about how we ought to think. This presupposes that logic is about thought or at least that it has something to do with reasoning. A philosophical contemporary debate about the normativity of logic questions the exact nature of the connection between logic and thought, and tries to assess the reasons for regarding logic as having a normative character. In this talk, we shall discuss this point and its essential connection with pluralism in logic.

### Friday, April 21st at 2:00pm (tea and cookies at 1:30pm)

#### *Speaker:* **Professor H. Turgay Kaptanoglu, Department of Mathematics, Bilkent University, Ankara**

*Title:* **Precise Inclusion Relations Among Bergman-Besov and Bloch-Lipschitz Spaces and H^\infty on the Unit Ball of C^n**

*Abstract: * We describe exactly and fully which of the spaces of holomorphic functions in the title are included in which others. We provide either new results or new proofs. More importantly, we construct explicit functions in each space that show our relations are strict and best possible.

Joint work with A. Ersin Ureyen of Anadolu University, Eskisehir, Turkey

### Tuesday, April 11th at 1:00pm (tea and cookies at 12:30pm), please note the change in date/time

#### *Speaker:* **Professor David Shoikhet, Holon Institute of Technology, The Technion Institute of Technology of Israel**

*Title:* **Old and New in Complex Dynamical Systems**

*Abstract: * Historically, complex dynamics and geometrical function theory have been intensively developed from the beginning of the twentieth century. They provide the foundations for broad areas of mathematics. In the last fifty years the theory of holomorphic mappings on complex spaces has been studied by many mathematicians with many applications to nonlinear analysis, functional analysis, differential equations, classical and quantum mechanics. The laws of dynamics are usually presented as equations of motion which are written in the abstract form of a dynamical system: ((dx)/(dt))+f(x)=0, where x is a variable describing the state of the system under study, and f is a vector-function of x. The study of such systems when f is a monotone or an accretive (generally nonlinear) operator on the underlying space has recently been the subject of much research by analysts working on quite a variety of interesting topics, including boundary value problems, integral equations and evolution problems.
In this talk we give a brief description of the classical statements which combine the celebrated Julia Theorem of 1920, Carathéodory's contribution in 1929 and Wolff's boundary version of the Schwarz Lemma of 1926 with their modern interpretations for discrete and continuous semigroups of hyperbolically non-expansive mappings in Hilbert spaces. We also present flow-invariance conditions for holomorphic and hyperbolically monotone mappings.
Finally, we study the asymptotic behavior of one-parameter continuous semigroups (flows) of holomorphic mappings. We present angular characteristics of the flows trajectories at their Denjoy-Wolff points, as well as at their regular repelling points (whenever they exist). This enables us by using linearization models in the spirit of functional Schroeder's and Abel's equations and eigen-value problems for composition operators to establish new rigidity properties of holomorphic generators which cover the famous Burns-Krantz Theorem and to solve a Nevanlinna-Pick type boundary interpolation problem for generators.

### Friday, April 7th at 2:00pm (tea and cookies at 1:30pm)

#### *Speaker:* **Dr. Imanol Mozo, Chapman University**

*Title:* **The unit circle in pointfree topology**

*Abstract: * Pointfree topology is an lattice-theoretic approach to topology that takes abstract lattices of open sets as the primitive notion. This approach is motivated by the fact that the lattice of open sets of a topological space contain almost all the information. Indeed, some lattices, namely, frames, are sufficiently similar to lattices of open sets of topological spaces in order to be considered as generalized spaces [5].
One of the main differences between pointfree topology and classical topology is that the category of frames is algebraic, while the dual of the category of topological spaces is not. Consequently, we can present its objects by generators and relations, as in an algebraic fashion. This is a very useful tool that was used by Joyal in order to introduce the pointfree counterpart of the real line [3], which was later studied by Banaschewski in [1]. Besides, this procedure offers a natural way to introduce variants by modifying the set of generators or the defining relations. For instance, one has the frame of extended reals and the lattice of extended real functions studied in [2], and the frame of partial reals and the lattice of continuous partial real functions introduced in [4] which arose naturally in the construction of the Dedekind completion of the lattice of continuous real functions on a frame.
In this talk, after a brief introduction to pointfree topology, we will discuss how the topology of the unit circle fits in this family of frames.

[1] B. Banaschewski, The real numbers in pointfree topology, Textos de Matemática vol. 12, Departamento de Matemática da Universidade de Coimbra (1997). [2] B. Banaschewski, J. Gutiérrez García, J. Picado, Extended real functions in pointfree topology, J. Pure Appl. Algebra 216 (2012), 905–922. [3] A. Joyal, Nouveaux fondaments de l’analyse. Lectures Montréal 1973 and 1974 (unpublished).971), 161–167. [4] I. Mozo Carollo, J. Gutiérrez García and J. Picado, On the Dedekind completion of function rings, Forum Math. 27 (2015), 2551 -2585. [5] J. Picado and A. Pultr, Frames and locales: Topology without points, Frontiers in Mathematics, vol. 28, Springer, Basel (2012).

### Friday, March 31st at 2:00pm (tea and cookies at 1:30pm) join with the Philosophy Department

#### *Speaker:* **Professor John Mumma, CalState San Bernardino**

*Title:* **Lewis's infinite regress, mathematical proof, and the act of diagramming **

*Abstract: * In 'What the Tortoise Said to Achilles.' Carroll shows how an infinite regress can be generated from the demand that all premises in a deductive inference be made explicit. In my talk I discuss the connection of the regress to the question of how mathematical proofs are accepted as proofs. A mathematical proof does not succeed unless it can be seen how acceptance of its premises force acceptance of its conclusion. Carroll's piece can be understood, I argue, as illuminating the difficulties in providing a satisfactory account of this seeing. I then focus on a restricted class of elementary geometric inferences, and explore whether the act of diagramming them resolves (for this restricted class) the general difficulties Carroll's piece raises.

### Friday, March 24th at 2:00pm (tea and cookies at 1:30pm)

#### *Speaker:* **Professor Dan Volok, Kansas State University, Department of Mathematics**

*Title:* **Non-stationary point evaluation in the multiscale setting**

*Abstract: * It was demonstrated by D. Alpay, P. Dewilde and H. Dym that the Hilbert space of triangular Hilbert-Schmidt operators can be equipped with a reproducing kernel structure quite similar to that of the classical Hardy space of the unit disk. This fact has many applications in the theory of non-stationary dissipative systems. It turns out that a multivariate generalization of Alpay-Dewilde-Dym reproducing kernel Hilbert space arises naturally in the setting of linear systems indexed by homogeneous trees, as introduced by A. Benveniste, R. Nikoukhah and A. Willsky.

This talk is based on joint work with D. Alpay and A. Dijksma.

### Friday, March 17th at 2:00pm (tea and cookies at 1:30pm)

#### *Speaker:* **Professor Palle Jorgensen, University of Iowa, Department of Mathematics**

*Title:* **Markov processes, endomorphisms, and measurable dynamics**

*Abstract: * The structures of positive operators, endomorphisms, transfer operators, measurable partitions, and Markov processes arise in both pure and applied mathematics. The talk offers unified setting, as well as new applications. The general setting is that of dynamics in Borel measure spaces and Markov fields. Hence the corresponding linear structures to be studied are infinite-dimensional. Nonetheless, we prove a number of analogues of the more familiar finite-dimensional settings, for example, the Perron-Frobenius theorem in the case of positive matrices, and the corresponding Markov chains.

### Friday, March 10th at 2:00pm (tea and cookies at 1:30pm)

#### *Speaker:* **Professor Howard Wiseman, Griffith University, and the Centre for Quantum Computation and Communication Technology**

*Title:* **What is Quantum Markovianity?**

*Abstract: * Markovianity versus non-Markovianity is a well-established distinction for classical systems. The same cannot be said for quantum systems. Different communities and individuals use “quantum Markovianity” to mean very different things. We argue that, to avoid confusion, it is best to avoid attributing that term any definite meaning at this stage. However, that does not mean that there is nothing to say about Markovianity for open quantum systens. We discuss a large number of concepts that have been, or could logically be, used to define quantum (non-)Markovianity, and prove hierarchical relations between them. Some are existing concepts, including “factorisation”, “quantum regression formula”, “divisibility”, and “Lindblad”. Others we introduce, including “past-future independence”, and “composability”. We also prove relations between these and other properties of interest for open quantum systems, such as the applicability of dynamical decoupling to preserve quantum information, the existence of (quantum) information backflow from the environment, and the physical reality of stochastic pure-state trajectories. Finally, we discuss in which concept the closest analogue of classical Markovianity lies.

Joint work with: Li (Kenny) Li, and Michael Hall

### Tuesday, March 7th at 5:30pm (tea and cookies at 5:00pm)

#### *Speaker:* **Professor Giuseppe Longo, CNRS, CREA, École Polytechnique, et CIRPHLES, ENS, Paris**

*Title:* **The Structuralist Roots of Mathematical Understanding Reconsidered: Poincaré’s heritage**

*Abstract: * The theological origin of the physicomathematical spaces; the geometrization of time
Abstract: There is no mathematical plane nor space in Euclid's geometry. Lines are traced, extended, intersected on a plane, an “apeiron” (it has no boundary), which is “practiced” but not mathematized. These lines have no thickness, they intersect in a point, that is a sign (“semeion”); they are objects of a mythical, ideal realm. Infinity is only potential: lines in the plane or endless sequences of numbers can be extended with no limit. Actual infinity will be fully conceptualized much later, in the theological debate of late middle age, as an attribute of God. How actual infinity relates to or how can it be represented in the finite? The Renaissance Italian painters will show that this is possible: the projective limit of the newly invented linear perspective, first used in XIV century paintings of the Annonciation, shows the infinite in the finite and joins the infinity of God to the bodily, three dimensional presence of a human being, the Madonna. We will critically analyze paintings from Giotto to Piero della Francesca that show this joint invention of actual infinity and of mathematical spaces, which allows as well the expression of a new, corporeal humanity. Later, this theological invention will become the mathematics of Descartes' and Desargues' spaces, the science of Newton's infinities. In the XIX century, physics will extend this mystical creation of infinite space and time to the mathematical “phase space” of its new scientific rigor, based on an increasing mathematical unity of space and time.

### Friday, February 17th at 2pm (tea and cookies at 1:30pm)

#### *Speaker:* **Andrew Jordan, University of Rochester**

*Title:* **Postselection, Superconductors, and Quantum Information in Black Holes**

*Abstract: * This talk will demonstrate how the quantum information entering black holes is analogous to quantum information entering a superconductor. The correspondence maps the interior of a black hole to a superconductor, and the exterior of the black hole to a normal metal. We show that the metal-superconductor interface can be thought of as an event horizon: The proximity effect in superconductor-metal interfaces (where Cooper pairs tend to form in the normal metal) is analogous to electron-positron creation at the event horizon in black-holes, which gives rise to Hawking radiation. Existing popular ideas of preserving quantum information entering black holes – the Preskill informational mirror, and the Horowitz-Maldacena mechanism for black-hole evaporation (which necessitates a unique final state for the black-hole), can be exactly incarnated as quantum information swapping or transfer using Andreev reflection processes. I will present mesoscopic physics analogs to wormholes and time loops using postselection on the superconducting ground state of a condensed gas of Cooper pairs – and conjecture that the BCS ground state also describes the final quantum state of a black hole.

### Wednesday, February 15th at noon (tea and cookies at 11:30am)

#### *Speaker:* **Gerhard Heinzmann, Université de Lorraine/CNRS & Archives Henri-Poincaré (UMR 7117), Nancy, France**

*Title:* **The Structuralist Roots of Mathematical Understanding Reconsidered: Poincaré’s heritage**

*Abstract: * This paper proposes a reconsideration of mathematical structuralism. It adopts the "practical turn" that owes much to Henri Poincare. By reconsstructing his group theoretic approach of geometry, it seems possible to explain the main difficulty of modern structuralism, inaugurated by the French collective Bourbaki around the middle of the XXth century: the unclear ontological status of ‘structures’ and ‘places’.
For Poincaré, the formation of the group concept - a 'universal' - is suggested by a specific system of stipulated sensations and, read as a relational set, the general group concept constitutes a model of the group axioms, which are exemplified (in the Goodmanien sense) by the sensation system. In other words, the shape created in the mind leads to a particular type of platonistic universals, which is a model (in the model theoretical sens) of the mathematical axiom system of the displacement group. The elements of the displacement group are independent and complet entities with respect to the axiom system of the group. But, by analysing the subgroups of the displacement group (common to geometries with constant curvature) one transformes the variables of the axiom system in ‘places’ whose ‘objects’ lack any ontological commitment except with respect to the specified axioms.
In general, a structure R is interpreted as a second order relation which is exemplified by (axiomatic) systems according to the pragmatic maxim of Charles Sanders Peirce.

### Friday, February 10th at 2pm (tea and cookies at 1:30pm)

#### *Speaker:* **Natalie Paquette, Burke Fellow, Walter Burke Institute of Theoretical Physics at CalTech**

*Title:* **Moonshine: Old and New**

*Abstract: * The whimsically-named Monstrous Moonshine is a mathematical story born in the late 1970's, which provided startling connections between two fundamental objects in mathematics. It eventually found an explanatory framework in the physics of an exotic solution of string theory. Starting in 2010, moonshine phenomena reemerged in the context of a more conceptually and physically central corner of string theory. In this talk, I will survey both old and new developments in moonshine with an emphasis on their physical meanings, and highlight the as-yet mysterious connections between the many beautiful mathematical and physical objects at play. I will summarize recent work clarifying these moonshine structures in string theory.

### Monday, February 6th to Saturday, February 11

#### *Speaker:* **9th ANNUAL CECAT WORKSHOP IN POINTFREE MATHEMATICS**

*Title:* **9th ANNUAL CECAT WORKSHOP IN POINTFREE MATHEMATICS**

*Abstract: * Talks in Von Neumann Hall throughout the week.

### Friday, February 3rd at 4pm (tea and cookies at 3:30pm)

#### *Speaker:* **Dr. Alberto Fernandez-Nieves, Professor of soft condensed matter physics at Georgia Tech**

*Title:* **Active nematics on tori**

*Abstract: * We will discuss our recent results with active nematics on toroidal surfaces. We will first
briefly describe how we generate and stabilize an otherwise unstable toroidal drop. We
use these droplets to study the interplay between nematic order, geometry and
topology. We find defect unbinding and defect-curvature coupling, consistent with
theoretical expectations for inactive ordered materials arranged on the surface a torus.
In our experiments, however, the number of defects is far larger than what one would
expect for inactive nematics. This brings about interesting analogies with what we could
call the high-temperature limit of inactive nematic liquid crystals.

### Monday, January 9th at 4pm (tea and cookies at 2:30pm)

#### *Speaker:* **Professor Uwe Kahler, Universidade de Aveiro, Portugal**

*Title:* **Riemann-Hilbert problems in Clifford analysis**

*Abstract: * One of the classic topics in Complex Analysis is the question of boundary value problems for holomorphic functions, so-called Riemann-Hilbert problems. This is not only for pure inner mathematical reasons, but also for its many applications, ranging from Materials with Memory, Inverse Scattering problems, to Statistical Physics. Due to its easy applicability since the beginning the question of Riemann-Hilbert problems in higher dimensions has caught the interest of many mathematicians. But there are essential differences between the two-dimensional case and the higher-dimensional case. In this talk we will present the general framework and highlight the difference between the two cases. Several open problems in the framework of hypercomplex analysis are being discussed.

### Monday, January 9th at 3pm (tea and cookies at 2:30pm)

#### *Speaker:* **Professor Paula Cerejeiras, Universidade de Aveiro, Portugal**

*Title:* **Applications of Monogenic Wavelets to Image Processing **

*Abstract: * We present an overview of applications of Clifford analysis to problems in image processing. As Clifford analysis techniques are strongly linked to the geometry of the underlying space it has generate an increasing interest in its applications to analytic signals in the last decade. Motivated by the problem of edge detection we introduce the concept of monogenic signal and discuss appropriate wavelet frames for it. We will finalize with a discussion on the group theoretical approach.