Cancellative partial monoids

Abbreviation: CanPMon

Definition

A \emph{cancellative partial monoid} is a partial monoid such that

$\cdot$ is \emph{left-cancellative}: $x\cdot y=x\cdot z\ne *$ implies $y=z$ and

$\cdot$ is \emph{right-cancellative}: $x\cdot z=y\cdot z\ne *$ implies $x=y$.

Morphisms

Let $\mathbf{A}$ and $\mathbf{B}$ be cancellative partial monoids. A morphism from $\mathbf{A}$ to $\mathbf{B}$ is a function $h:A\rightarrow B$ that is a homomorphism: $h(e)=e$ and if $x\cdot y\ne *$ then $h(x \cdot y)=h(x) \cdot h(y)$.

Example 1:

Properties

Classtype first-order

Finite members

$\begin{array}{lr} f(1)= &1\\ f(2)= &2\\ f(3)= &3\\ f(4)= &9\\ f(5)= &21\\ f(6)= &125\\ f(7)= &\\ f(8)= &\\ f(9)= &\\ f(10)= &\\ \end{array}$