# Tacit extension

In logic and mathematics, a **tacit extension** is an injection of a set into a cartesian product that has that set as one of its factors. There are many such injections, all of which serve as inverse operations to the projection of the Cartesian product onto the set in question, but the tacit extension is the one that places no additional constraints on the injection mapping.

## See also

## Document history

Portions of the above article were adapted from the following sources under the GNU Free Documentation License, under other applicable licenses, or by permission of the copyright holders.