# Differences

This shows you the differences between two versions of the page.

— |
quasitrivial_groupoids [2010/07/29 15:46] (current) |
||
---|---|---|---|

Line 1: | Line 1: | ||

+ | =====Quasitrivial groupoids===== | ||

+ | |||

+ | Abbreviation: **QtGrpd** | ||

+ | |||

+ | ====Definition==== | ||

+ | A \emph{quasitrivial groupoid} is a [[groupoid]] $\mathbf{A}=\langle A,\cdot\rangle$ such that | ||

+ | |||

+ | $\cdot$ is \emph{quasitrivial}: $x\cdot y=x\text{ or }x\cdot y=y$ | ||

+ | |||

+ | Remark: This is a template. | ||

+ | If you know something about this class, click on the 'Edit text of this page' link at the bottom and fill out this page. | ||

+ | |||

+ | It is not unusual to give several (equivalent) definitions. Ideally, one of the definitions would give an irredundant axiomatization that does not refer to other classes. | ||

+ | |||

+ | ==Morphisms== | ||

+ | Let $\mathbf{A}$ and $\mathbf{B}$ be quasitrivial groupoids. A morphism from $\mathbf{A}$ to $\mathbf{B}$ is a function $h:A\rightarrow B$ that is a homomorphism: | ||

+ | $h(x \cdot y)=h(x) \cdot h(y)$ | ||

+ | |||

+ | ====Definition==== | ||

+ | An \emph{...} is a structure $\mathbf{A}=\langle A,...\rangle$ of type $\langle | ||

+ | ...\rangle$ such that | ||

+ | |||

+ | $...$ is ...: $axiom$ | ||

+ | |||

+ | $...$ is ...: $axiom$ | ||

+ | |||

+ | ====Examples==== | ||

+ | Example 1: | ||

+ | |||

+ | ====Basic results==== | ||

+ | Quasitrivial groupoids are in 1-1 correspondence with [[reflexive relations]]. E.g. a translations is given by $x\cdot y=x$ iff $\langle x,y\rangle\in E$. | ||

+ | |||

+ | |||

+ | ====Properties==== | ||

+ | Feel free to add or delete properties from this list. The list below may contain properties that are not relevant to the class that is being described. | ||

+ | |||

+ | ^[[Classtype]] |universal | | ||

+ | ^[[Equational theory]] | | | ||

+ | ^[[Quasiequational theory]] | | | ||

+ | ^[[First-order theory]] | | | ||

+ | ^[[Locally finite]] | | | ||

+ | ^[[Residual size]] | | | ||

+ | ^[[Congruence distributive]] | | | ||

+ | ^[[Congruence modular]] | | | ||

+ | ^[[Congruence $n$-permutable]] | | | ||

+ | ^[[Congruence regular]] | | | ||

+ | ^[[Congruence uniform]] | | | ||

+ | ^[[Congruence extension property]] | | | ||

+ | ^[[Definable principal congruences]] | | | ||

+ | ^[[Equationally def. pr. cong.]] | | | ||

+ | ^[[Amalgamation property]] | | | ||

+ | ^[[Strong amalgamation property]] | | | ||

+ | ^[[Epimorphisms are surjective]] | | | ||

+ | |||

+ | ====Finite members==== | ||

+ | |||

+ | $\begin{array}{lr} | ||

+ | f(1)= &1\\ | ||

+ | f(2)= &\\ | ||

+ | f(3)= &\\ | ||

+ | f(4)= &\\ | ||

+ | f(5)= &\\ | ||

+ | \end{array}$ | ||

+ | $\begin{array}{lr} | ||

+ | f(6)= &\\ | ||

+ | f(7)= &\\ | ||

+ | f(8)= &\\ | ||

+ | f(9)= &\\ | ||

+ | f(10)= &\\ | ||

+ | \end{array}$ | ||

+ | |||

+ | |||

+ | ====Subclasses==== | ||

+ | [[...]] subvariety | ||

+ | |||

+ | [[...]] expansion | ||

+ | |||

+ | |||

+ | ====Superclasses==== | ||

+ | [[...]] supervariety | ||

+ | |||

+ | [[...]] subreduct | ||

+ | |||

+ | |||

+ | ====References==== | ||

+ | |||

+ | [(Lastname19xx> | ||

+ | F. Lastname, \emph{Title}, Journal, \textbf{1}, 23--45 [[MRreview]] | ||

+ | )] | ||

+ | |||

+ | |||

Trace: