Symbols:Abbreviations

iff
"If and only if".

WLOG
"Without loss of generality".

Suppose there are several cases which need to be investigated.

If the same argument can be used to dispose of two or more of these cases, then it is acceptable in a proof to pick just one of these cases, and announce this fact with the words: "Without loss of generality, ...", or just "WLOG".

WRT
"With respect to".

When performing calculus operations, i.e. differentiation or integration, one needs to announce which variable one is "working with".

Thus the phrase "with respect to" is (implicitly or explicitly) part of every statement in calculus.

Thus the abbreviation "WRT" or "w.r.t." is frequently seen.