# [OS X TeX] Latex symbol for "define equal"

Ettore Aldrovandi ealdrov at math.fsu.edu
Sun Aug 19 16:44:08 EDT 2018

> On Aug 19, 2018, at 05:53, Themis Matsoukas <tmatsoukas at icloud.com> wrote:
>
>>
>> BTW, the last time I used \equiv for defining something (something like $E_{d,\gamma}f\equiv f$, a referee swatted it down.  :=)
>>
>
> …and good to know that \equiv is unacceptable :)

I tend to not use \equiv, but rather favor := (or even = with ‘def’ on top) for an “equal by definition,” where in effect the term on the left is introduced for the first time. The \equiv lends itself better to express an identity between two terms. In other words, and extending a bit, \equiv expresses the idea of a “canonical isomorphism,” and therefore \cong (or some such) just is an isomorphism.

My two math cents.

—Ettore

Ettore Aldrovandi
Department of Mathematics, Florida State University