Recent Comments

Recent Posts
 זה הזמן לשינוי
 Combinatorics and More – Greatest Hits
 Ilan and me
 The Simplex, the Cyclic polytope, the Positroidron, the Amplituhedron, and Beyond
 From Oberwolfach: The Topological Tverberg Conjecture is False
 Midrasha Mathematicae #18: In And Around Combinatorics
 Quantum computing: achievable reality or unrealistic dream
 A Historical Picture Taken by Nimrod Megiddo
 Scott Triumphs* at the Shtetl
Top Posts & Pages
 זה הזמן לשינוי
 Combinatorics and More  Greatest Hits
 The Simplex, the Cyclic polytope, the Positroidron, the Amplituhedron, and Beyond
 The Ultimate Riddle
 Believing that the Earth is Round When it Matters
 Academic Degrees and Sex
 Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
 Extremal Combinatorics I: Extremal Problems on Set Systems
 Helly's Theorem, "Hypertrees", and Strange Enumeration I
RSS
Search Results for: erdos
A Discrepancy Problem for Planar Configurations
Yaacov Kupitz and Micha A. Perles asked: What is the smallest number C such that for every configuration of n points in the plane there is a line containing two or more points from the configuration for which the difference between the … Continue reading
Polymath5 – Is 2 logarithmic in 1124?
Polymath5 – The Erdős discrepancy problem – is on its way. Update: Gowers’s theoretical post marking the official start of Polymath 5 appeared. Update (February 2014): Boris Konev and Alexei Lisitsa found a sequence of length 1160 of discrepancy 2 … Continue reading
Four Derandomization Problems
Polymath4 is devoted to a question about derandomization: To find a deterministic polynomial time algorithm for finding a kdigit prime. So I (belatedly) devote this post to derandomization and, in particular, the following four problems. 1) Find a deterministic algorithm for primality 2) Find … Continue reading
Posted in Computer Science and Optimization, Probability
Tagged derandomization, polymath4, Randomness
5 Comments
Vitali Fest
Last week I took part in a lovely and impressive conference on the state of geometry and functional analysis, celebrating Vitali Milman’s 70th birthday. The conference started in Tel Aviv, continued at the Dead Sea, and returned to Tel Aviv. I gave a … Continue reading
Posted in Conferences
5 Comments
The CapSet Problem and FranklRodl Theorem (C)
Update: This is a third of three posts (part I, part II) proposing some extensions of the cap set problem and some connections with the Frankl Rodl theorem. Here is a post presenting the problem on Terry Tao’s blog (March 2007). Here … Continue reading
Posted in Combinatorics, Open problems
Tagged Cap sets, FranklRodl theorem, polymath1
Leave a comment
Extremal Combinatorics on Permutations
We talked about extremal problems for set systems: collections of subsets of an element sets, – Sperner’s theorem, the ErdosKoRado theorem, and quite a few more. (See here, here and here.) What happens when we consider collections of permutations rather … Continue reading
Posted in Combinatorics
Tagged ErdosKoRado theorem, Extremal combinatorics, Permutations
9 Comments
Polymath1: Success!
“polymath” based on internet image search And here is a link to the current draft of the paper. Update: March 26, the name of the post originally entitled “Polymath1: Probable Success!” was now updated to “Polymath1: Success!” It is now becoming … Continue reading
Posted in Blogging, Combinatorics, What is Mathematics
Tagged Density HalesJewett theorem, polymath1
10 Comments
FranklRodl’s Theorem and Variations on the Cap Set Problem: A Recent Research Project with Roy Meshulam (A)
Voita Rodl I would like to tell you about a research project in progress with Roy Meshulam. (We started it in the summer, but then moved to other things; so far there are interesting insights, and perhaps problems, but not substantial … Continue reading
Posted in Combinatorics, Open problems
Tagged Cap sets, Extremal combinatorics, Intersection theorems, polymath1
6 Comments
Mathematics, Science, and Blogs
Michael Nielsen wrote a lovely essay entitled “Doing science online” about mathematics, science, and blogs. Michael’s primary example is a post over Terry Tao’s blog about the NavierStokes equation and he suggests blogs as a way of scaling up scientific conversation. Michael is writing … Continue reading
Posted in Blogging, What is Mathematics
Tagged Blogs, Michael Nielsen, Open science, polymath1, Tim Gowers
5 Comments
Lior, Aryeh, and Michael
Three dear friends, colleagues, and teachers Lior Tzafriri, Aryeh Dvoretzky and Michael Maschler passed away last year. I want to tell you a little about their mathematics. Lior Tzafriri ( 19362008 ) Lior Tzafriri worked in functional analysis.