\begin{definition}[Definition:Cancellable Element/Right Cancellable]
Let $\struct {S, \circ}$ be an algebraic structure.
An element $x \in \struct {S, \circ}$ is '''right cancellable''' {{iff}}:
:$\forall a, b \in S: a \circ x = b \circ x \implies a = b$
\end{definition}