## Archive for February 26, 2013

### Guest Blog @ Proofs from the Book

I discovered Guillermo Bautista’s blog *Proofs from the Book* about a month ago, and I wrote about it last week. But just yesterday, Guillermo published a guest post showing the connection between proofs and jokes written by little ol’ me. His blog is worth checking out whether you want to read my post or not.

Paul Erdös once said, “You don’t have to believe in God, but you should believe in *The Book*.” He was referring to a mystical book in which the most elegant proofs of all theorems appear. *The Book* is the inspiration for the name of Guillermo’s new blog. Unfortunately, Martin Aigner and Günter M. Ziegler had the same inspiration when they published *Proofs from THE BOOK* in 1998. Some may think that this duplication is unfortunate. But I say that sometimes lightning strikes twice. After all, if Newton and Liebniz can both be credited for discovering the calculus, then Guillermo deserves as much credit as others for coming up with this awesome name.

The following are some methods of proof that are covered neither in the book *Proofs from THE BOOK* or at the blog *Proofs from the Book*.

Proof by Obviousness: “The proof is so clear that it need not be mentioned.”

Proof by Lack of Sufficient Time: “Because of the time constraint, I’ll leave the proof to you.”

Proof by Lack of Sufficient Space: “I have discovered a truly marvelous proof of this [theorem], which this margin is too narrow to contain.”

Proof by General Agreement: “All in favor?”

Proof by Imagination: “Wel, let’s pretend it’s true.”

Proof by Necessity: “It had better be true, or the entire structure of mathematics would crumble to the ground.”

Proof by Plausibility: “It sounds good, so we’ll assume it’s true.”

Proof by Intimidation: “Don’t be stupid; of course, it’s true.”

Proof by Accident: “Hey, what have we here?”