Author Archives: Gil Kalai

זה הזמן לשינוי

Posted on March 1, 2015

זו הפעם החמש-עשרה שבה אצביע והפעם השלישית שאנו נמצאים לפני בחירות מאז שהתחלתי בכתיבת הבלוג. בעבר לא הבעתי בפומבי את הבחירה האישית שלי. עבורי יום הבחירות הוא יום חג, ההכרעות בין  תפיסות עולם ואינטרסים מנוגדים אינן קלות, ויש דרכים שונות, … Continue reading →

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Combinatorics and More – Greatest Hits

Posted on February 27, 2015

Combinatorics and More’s Greatest Hits First Month Combinatorics, Mathematics, Academics, Polemics, … Helly’s Theorem, “Hypertrees”, and Strange Enumeration I (There were 3 follow up posts:) Extremal Combinatorics I: Extremal Problems on Set Systems (There were 4 follow up posts II ; III; IV; VI) Drachmas Rationality, Economics and … Continue reading →

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Ilan and me

Posted on February 23, 2015

  With Ilan, my four month old grandson  

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The Simplex, the Cyclic polytope, the Positroidron, the Amplituhedron, and Beyond

Posted on February 16, 2015

A quick schematic road-map to these new geometric objects. The  positroidron can be seen as a cellular structure on the nonnegative Grassmanian – the part of the real Grassmanian G(m,n) which corresponds to m by n matrices with all m by … Continue reading →

Posted in Algebra and Number Theory, Combinatorics, Convex polytopes, Physics | Tagged , , , , , , | 1 Comment

From Oberwolfach: The Topological Tverberg Conjecture is False

Posted on February 6, 2015

The topological Tverberg conjecture (discussed in this post), a holy grail of topological combinatorics, was refuted! The three-page paper “Counterexamples to the topological Tverberg conjecture” by Florian Frick gives a brilliant proof that the conjecture is false. The proof is … Continue reading →

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Midrasha Mathematicae #18: In And Around Combinatorics

Posted on January 20, 2015

  Tahl Nowik                  Update 3 (January 30): The midrasha ended today. Update 2 (January 28): additional videos are linked; Update 1 (January 23): Today we end the first week of the school. David Streurer and Peter Keevash completed … Continue reading →

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Quantum computing: achievable reality or unrealistic dream

Posted on January 10, 2015

  Michel Dyakonov’s View on QC                                     My view (based on Michel’s drawing*) Update: Alexander Vlasov’s view (based on Michel and Konstantin’s drawing) … Continue reading →

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A Historical Picture Taken by Nimrod Megiddo

Posted on December 31, 2014

Last week I took a bus from Tel Aviv to Jerusalem and I saw (from behind) a person that I immediately recognized. It was Nimrod Megiddo, from IBM Almaden, one of the very first  to relate game theory with complexity … Continue reading →

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Scott Triumphs* at the Shtetl

Posted on December 31, 2014

Scott Aaronson wrote a new post on the Shtetl Optimized** reflecting on the previous thread  (that I referred to in my post on Amy’s triumph), and on reactions to this thread. The highlight is a list of nine of Scott’s … Continue reading →

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Amy Triumphs* at the Shtetl

Posted on December 27, 2014

It was not until the 144th comment by a participants named Amy on Scott’s Aaronson recent Shtetl-optimized** post devoted to a certain case of sexual harassment at M. I. T. that the discussion turned into something quite special. Amy’s great … Continue reading →

Posted in Controversies and debates, Women in science | Tagged , , | 23 Comments