Abbreviation: CBinOp
A \emph{commutative groupoid} is a structure $\mathbf{A}=\langle A,\cdot\rangle$ where $\cdot$ is any commutative binary operation on $A$, i.e. $x\cdot y=y\cdot x$
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:
$h(x\cdot y)=h(x)\cdot h(y)$
Example 1:
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 |
$\begin{array}{lr}
f(1)= &1\\ f(2)= &\\ f(3)= &\\ f(4)= &\\ f(5)= &\\ f(6)= &\\
\end{array}$
[[Commutative semigroups]]
[[Idempotent commutative groupoids]]
[[Commutative left-distributive groupoids]]
[[Groupoids]]