# 36 ways of mathematical proof

7 posts

 Proof by obviousness: “The proof is so clear that it need not be mentioned.” Proof by general agreement: “All in favor?…” Proof by imagination: “Well, we’ll pretend it’s true…” Proof by convenience: “It would be very nice if it were true, so…” 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 it must be true.” Proof by intimidation: “Don’t be stupid; of course it’s true!” Proof by lack of sufficient time: “Because of the time constrait, I’ll leave the proof to you.” Proof by postponement: “The proof for this is long and arduous, so it is given to you in the appendix.” Proof by accident: “Hey, what have we here?!” Proof by insignificance: “Who really cares anyway?” Proof by mumbo-jumbo: ![](http://jwilson.coe.uga.edu/EMT668/EMAT6680.F99/Challen/proof/mumbo.gif) Proof by profanity: (example omitted) Proof by definition: “We define it to be true.” Proof by tautology: “It’s true because it’s true.” Proof by plagarism: “As we see on page 289,…” Proof by lost reference: “I know I saw it somewhere….” Proof by calculus: “This proof requires calculus, so we’ll skip it.” Proof by terror: When intimidation fails… Proof by lack of interest: “Does anyone really want to see this?” Proof by illegibility: ![](http://jwilson.coe.uga.edu/EMT668/EMAT6680.F99/Challen/proof/illeg.gif) Proof by logic: “If it is on the problem sheet, it must be true!” Proof by majority rule: Only to be used if general agreement is impossible. Proof by clever variable choice: “Let A be the number such that this proof works…” Proof by tessellation: “This proof is the same as the last.” Proof by divine word: “…And the Lord said, ‘Let it be true,’ and it was true.” Proof by stubbornness: “I don’t care what you say- it is true.” Proof by simplification: “This proof reduced to the statement 1 + 1 = 2.” Proof by hasty generalization: “Well, it works for 17, so it works for all reals.” Proof by deception: “Now everyone turn their backs…” Proof by supplication: “Oh please, let it be true.” Proof by poor analogy: “Well, it’s just like…” Proof by avoidance: Limit of proof by postponement as it approaches infinity Proof by design: If it’s not true in today’s math, invent a new system in which it is. Proof by authority: “Well, Don Knuth says it’s true, so it must be!” Proof by intuition: “I have this gut feeling.” [http://jwilson.coe.uga.edu/EMT668/EMAT6680.F99/Challen/proof/proof.html](http://jwilson.coe.uga.edu/EMT668/EMAT6680.F99/Challen/proof/proof.html) As a mathematician you would find this funny… Only if all math are like this… [http://en.wikipedia.org/wiki/Invalid\_proof](http://en.wikipedia.org/wiki/Invalid_proof) Some of these were pretty funny too… Another I’ve heard of is “Proof by vigorous hand-waving” but I did chuckle quietly when I read this post =] Nice find. Proof by Marh: “I got a B, so it’s probably right”. I remember one similar to > Proof by lost reference: “I know I saw it somewhere….” that we had in a lecture: Proof by unobtainable reference: “As shown in the Lithuanian Mathematics Journal of Spring 1957…” I like proof by obviousness / clarity too, tried to use that in some assignments :) There’s an anecdote at my uni (and probably every other uni too) about a lecturer who wrote up a Theorem, then “The proof is trivial”. Then he said “Wait a second, IS it trivial?” Left the lecture theatre to think about it and half an hour later returned and exclaimed “Yes, it is definitely trivial!” and continued the lecture. Lol. “Proof by calculus: “This proof requires calculus, so we’ll skip it.” " I have taken calculus. Therefore, I can’t use this proof anymore. … … Shit, that was my entire math career. > Proof by profanity: (example omitted)> Proof by divine word: “…And the Lord said, ‘Let it be true,’ and it was true.”> Proof by definition: “We define it to be true.” My favorites.