# Math vocab: operator on $S$ and into $S =$?

Is there a special name for a binary operation on the set $S$ that is also into $S$, that is unambiguous with other uses. I.e. if it's "operator on $S$", I've heard that in other places meaning the operator could map to another set $T$. I'm working on a math library in the D language.

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A binary operation on a set $S$ is, by definition, a map $S\times S\to S$. Is that what you are looking for? –  Arturo Magidin Mar 25 '12 at 3:17
endomap: $S\times S \to S$ –  user2468 Mar 25 '12 at 3:21
BTW the tag (computer-science) is not relevant. The context was already set by OP in his/her sentence: ".. the D language." –  user2468 Mar 25 '12 at 3:25
@J.D.: I don't like that: "endomap" suggests a map form a set to itself. –  Arturo Magidin Mar 25 '12 at 3:27