=====Ockham algebras===== Abbreviation: **OckA** ====Definition==== An \emph{Ockham algebra} is a structure $\mathbf{A}=\langle A,\vee ,0,\wedge ,1,'\rangle $ such that $\langle A,\vee ,0,\wedge ,1\rangle $ is a bounded distributive lattice $'$ is a dual endomorphism: $(x\wedge y)' =x'\vee y'$, $ (x\vee y)' =x'\wedge y'$, $ 0'=1$, $1'=0$ ==Morphisms== Let $\mathbf{A}$ and $\mathbf{B}$ be Ockham algebras. A morphism from $\mathbf{A}$ to $\mathbf{B}$ is a function $h:A\rightarrow B$ that is a homomorphism: $h(x\vee y)=h(x)\vee h(y)$, $h(x\wedge y)=h(x)\wedge h(y)$, $h(x')=h(x)'$, $h(0)=0$, $h(1)=1$ ====Examples==== Example 1: ====Basic results==== ====Properties==== ^[[Classtype]] |Variety | ^[[Equational theory]] | | ^[[Quasiequational theory]] | | ^[[First-order theory]] | | ^[[Congruence distributive]] |Yes | ^[[Congruence modular]] |Yes | ^[[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]] | | ^[[Locally finite]] | | ^[[Residual size]] | | ====Finite members==== $\begin{array}{lr} f(1)= &1\\ f(2)= &1\\ f(3)= &2\\ f(4)= &\\ f(5)= &\\ f(6)= &\\ f(7)= &\\ f(8)= &\\ f(9)= &\\ f(10)= &\\ \end{array}$ ====Subclasses==== [[De Morgan algebras]] ====Superclasses==== [[Bounded distributive lattices]] ====References==== [(Ln19xx> )]\end{document} %