Bullet Proof

This proof can suffer slings and arrows.  It can withstand all manner of flak.  It’s a bullet proof proof.


Burden of Proof

In the Pulitzer Prize winning play "Proof" by David Auburn, dementia is the burden of mathematics professor Llewelyn and his daughter Catherine who cares for him.


Sound Proof

When the proof is sound, even the loudest critic will be silenced.



To reproof is to criticise.  So when your professor scoffs and hands it back, you have been reproofed to reprove your proof.



A proofreader is someone who reads proofs – such as a professor grading Advanced Calc homework.


Goof Proof

Oh no!  There’s a goof in my proof!


Proof of Purchase

L'Hôpital struck a financial arrangement with Johann Bernoulli in 1694 whereby Johann would instruct L'Hôpital on Johann’s discoveries in calculus.  L'Hôpital published all of Johann’s results in L'Analyse des Infiniment Petits pour l'Intelligence des Lignes Courbes in 1696.  Although L'Hôpital’s book was published anonymously and thanked Johann in the preface for his many “bright ideas”, the credit for this great book soon made its way to L'Hôpital.


After L'Hôpital's death in 1704 Johann broke his silence and announced how L'Analyse had come to be.  Unfortunately Johann was not widely believed at the time.  However, history was set straight in 1922 by the discovery in Basel of an early copy of Johann’s notes.


Perhaps the greatest of all the results to be found in L'Analyse is still known today as L'Hôpital’s Rule.  So it is apt to label L'Hôpital’s Rule as a “proof of purchase” (purchased proof).  The moral of this story – always get a proof of purchase for your purchased proofs.



Hey I got it! This proof is over.  Q.E.D.




Burden of Proof (fallacy) – assuming a statement true because there exists no proof that the statement if false

Goof Proof – a process that you can’t mess up, even if you try

Overproof – containing more than 50% alcohol by volume