Partial unary operation
= Partial unary operation
{title2=$\alpha:D\subseteq A\to A$}
A partial unary operation on a set $A$ is a <partial function> with specified domain $D\subseteq A$ and values in $A$. A map preserving such operations must send each point of the source domain into the target domain and preserve its assigned value. It need not reflect whether the operation is defined.