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 Test your intuition 24: Which of the following three groups is trivial
 School Starts at HUJI
 A lecture by Noga
 Ehud Friedgut: Blissful ignorance and the KahnemanTversky paradox
 In And Around Combinatorics: The 18th Midrasha Mathematicae. Jerusalem, JANUARY 1831
 Mathematical Gymnastics
 Media Item from “Haaretz” Today: “For the first time ever…”
 Jim Geelen, Bert Gerards, and Geoﬀ Whittle Solved Rota’s Conjecture on Matroids
 Media items on David, Amnon, and Nathan
Top Posts & Pages
 Test your intuition 24: Which of the following three groups is trivial
 Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
 Believing that the Earth is Round When it Matters
 Polymath 8  a Success!
 The KadisonSinger Conjecture has beed Proved by Adam Marcus, Dan Spielman, and Nikhil Srivastava
 Extremal Combinatorics VI: The FranklWilson Theorem
 Extremal Combinatorics III: Some Basic Theorems
 Why Quantum Computers Cannot Work: The Movie!
 Mathematical Gymnastics
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Monthly Archives: November 2008
Sarkaria’s Proof of Tverberg’s Theorem 2
Karanbir Sarkaria 4. Sarkaria’s proof: Tverberg’s theorem (1965): Let be points in , . Then there is a partition of such that . Proof: We can assume that . First suppose that the points belong to the dimensional affine space … Continue reading
Sarkaria’s Proof of Tverberg’s Theorem 1
Helge Tverberg Ladies and gentlemen, this is an excellent time to tell you about the beautiful theorem of Tverberg and the startling proof of Sarkaria to Tverberg’s theorem (two parts). A good place to start is Radon’s theorem. 1. The theorems of Radon, … Continue reading
Bad Advice; An Answer to an Old Trivia Question
A transparency and a lecture using transparencies. (No relation to the advice.) Our bad, worse and worst advice corner Bad  When you give a talk with transparencies or computer presentations, don’t go over the content of the transparencies but rather assume … Continue reading
Thomas Bayes and Probability
How can we assign probabilities in cases of uncertainty? And what is the nature of probabilities, to start with? And what is the rational mechanism for making a choice under uncertainty? Thomas Bayes lived in the eighteenth century. Bayes’ famous … Continue reading
About Conjectures: Shmuel Weinberger
The following paragraph is taken from the original “too personal for publication draft” of an article entitled ” ‘Final values’ of functors” by Shmuel Weinberger for a volume in honor of Guido Mislin’s retirement from ETH. (L’enseignement Mathematique 54(2008), 180182.) Shmuel’s remarks … Continue reading
Would you decide the election if you could?
One mental experiment I am fond of asking people (usually before elections) is this: Suppose that just a minute before the votes are counted you can change the outcome of the election (say, the identity of the winner, or even … Continue reading
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Impagliazzo’s Multiverse
Update (July 2009): Here are links to a related post on Lipton’s blog, and a conference announcement on Russell’s possible worlds. On the occasion of Luca’s post on his FOCS 2008 tutorial on averagecase complexity here is a reminder of Russell … Continue reading
Detrimental Noise
“Imagine there’s no heaven, it’s easy(?) if you try,” John Lennon Disclaimer: It is a reasonable belief (look here, and here), and an extremely reasonable working assumption (look here) that computationally superior quantum computers can be built. (This post and the … Continue reading