WLOG
without loss of generality. ``I'm only going to show you part of the proof because the rest is exactly the same.''
st
such that.
QED
quod erat demonstrandum (``which was to be proved''). Marks the end of a proof. Nowadays, textbooks and scholarly papers often use a small black square instead. Maths majors and graduate students, on the other hand, usually mark the end of their proofs by drinking heavily and passing out slumped over the paper or keyboard. Kids, don't try this at home.
CQFD
ce qu'il fallait démontrer. French for QED.
wrt
with respect to.
TFAE
the following are equivalent. Proceeds a list of logical statements which are claimed or proved to be logically equivalent to one another.
TAMO
then a miracle occurs. ``I have no idea how to finish this proof.'' Usually found in answers to exam problems.
ICBS
it can be shown. The more respectable form of `TAMO'. Unlike TAMO, this one appears in serious mathematical writing.
wff
well-formed formula. In logic, formal systems, and such.