# Definition:Mutatis Mutandis

## Definition

**Mutatis mutandis** is Latin for **what needs changing having been changed**.

It can be used in place of words like *analogously* and *similarly*, and expresses that an argument can be applied to a new situation in an intuitive fashion.

For example the proof of Union is Associative can be made into that for Intersection is Associative by **mutatis mutandis**.

In this case, this comes down to replacing $\cup$ by $\cap$, and $\lor$ by $\land$.

In particular, the essential flow of the argument was not changed in adapting the proof.