= Equivalence of partial functions modulo finite changes
Two <functions> $f:A\to X$ and $g:B\to X$, whose domains lie in one ambient <set>, are equivalent modulo finite changes when $A\mathbin\triangle B$ is a <finite set> and the <functions> disagree at only finitely many points of $A\cap B$. The <symmetric difference> inclusion $A\mathbin\triangle C\subseteq(A\mathbin\triangle B)\cup(B\mathbin\triangle C)$ handles domains in a transitive chain. An exceptional <set> for values must also include points of $A\cap C$ absent from the middle domain $B$; these lie in the finite difference $A\setminus B$.
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