=====Commutative Groupoids===== Abbreviation: **CBinOp** ====Definition==== A \emph{commutative groupoid} is a structure $\mathbf{A}=\langle A,\cdot\rangle$ where $\cdot$ is any commutative binary operation on $A$, i.e. $x\cdot y=y\cdot x$ ==Morphisms== Let $\mathbf{A}$ and $\mathbf{B}$ be commutative groupoids. A morphism from $\mathbf{A}$ to $\mathbf{B}$ is a function $h:A\rightarrow B$ that is a homomorphism: $h(x\cdot y)=h(x)\cdot h(y)$ ====Examples==== Example 1: ====Basic results==== ====Properties==== ^[[Classtype]] | variety | ^[[Equational theory]] | decidable | ^[[Quasiequational theory]] | | ^[[First-order theory]] | undecidable | ^[[Locally finite]] | no | ^[[Residual size]] | unbounded | ^[[Congruence distributive]] | no | ^[[Congruence modular]] | no | ^[[Congruence n-permutable]] | no | ^[[Congruence regular]] | no | ^[[Congruence uniform]] | no | ^[[Congruence extension property]] | no | ^[[Definable principal congruences]] | no | ^[[Equationally def. pr. cong.]] | no | ^[[Amalgamation property]] | yes | ^[[Strong amalgamation property]] | yes | ^[[Epimorphisms are surjective]] | yes | ====Finite members==== $\begin{array}{lr} f(1)= &1\\ f(2)= &\\ f(3)= &\\ f(4)= &\\ f(5)= &\\ f(6)= &\\ \end{array}$ ====Subclasses==== [[Commutative semigroups]] [[Idempotent commutative groupoids]] [[Commutative left-distributive groupoids]] ====Superclasses==== [[Groupoids]] ====References==== [(Ln19xx> )]