Category Archives: Mathematical logic and set theory

Joel David Hamkins’ 1000th MO Answer is Coming

Posted on January 29, 2014 by

Updates (May 2014): The second MO contributor to answer 1000 questions is another distinguished mathematician (and a friend) Igor Rivin.  In summer 2015 David Speyer joined the club. (May 2018) Igor is the first MO user to have 2000 posts (Questions+Answers)! … Continue reading →

Posted in Mathematical logic and set theory, Mathematics over the Internet | Tagged , | 3 Comments

A Theorem About Infinite Cardinals Everybody Should Know

Posted on January 18, 2012 by

Cantor proved and we all know that for every cardinal  we have This is a very basic fact about cardinal arithmetic and it is nice that the proof works for finite and infinite cardinals equally well. (For the finite case it … Continue reading →

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