Ezra's Research

It's customary to indicate the end of a proof with a little square (a "tombstone"), with "Q.E.D.," or elsewise. These marks almost never seem helpful to me, but there are other points where significant proof obligations are discharge, and I wish these were marked.

One instance is the end of a case, in a proof by cases. Each of these is a major branch of the proof, which dead-ends in the middle. Variables may be brought into scope, which evaporate when the case is completed, so it's important to know the bounds of that case.

My contribution, then, to the technique of proof-by-cases, is to introduce the marker "huzzah!" indicating the simple end of a case as well as one's excitement at having proven something—a miminal proof-unit, perhaps. Here it is in a screenshot:

Having trouble achieving this effect yourself? Here's a TeX macro:

\def\huzzah{\hfill\emph{huzzah!}}

Update: According to Wikipedia, "Paul Sally at the University of Chicago is known for ending proofs with a pirate face symbol." This doesn't seem to be true of the couple of books coauthored by Sally that I could get through Google Books.