Month: October 2015
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Problemas señeros (I)
Abstract. In this series of posts I’ll discuss problems that can be posed in an elementary way but the only way to solve them (to the best of my knowledge) is to develop some set theory. This post is dedicated to a problem appearing in Fraenkel’s Set Theory , that states that you can change…
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Publish NOW, or perish
Academic life has given me a lesson for the second time, and it was harsh this time. The first lesson had a happy ending, and it can be described by the following words: Beware of the paper bin! This happened on 2008. I was experimenting with a really wonderful software, the bundle Prover9-Mace4, by the…
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How about a little absurdity?
Assume you want to prove a Theorem X. If you’re a fan of reductio ad absurdum (RAA), you start by saying “Assume that Theorem X is false. Hence…” and after some reasoning, you reach a contradiction. You write as a closing sentence, “This contradiction shows that Theorem X must be true.” I want to argue about…