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### Recent Posts

- To cheer you up in difficult times 9: Alexey Pokrovskiy proved that Rota’s Basis Conjecture holds asymptotically
- To Cheer you up in Difficult Times 8: Nathan Keller and Ohad Klein Proved Tomaszewski’s Conjecture on Randomly Signed Sums
- Noam Lifshitz: A new hypercontractivity inequality — The proof!
- To cheer you up in difficult times 7: Bloom and Sisask just broke the logarithm barrier for Roth’s theorem!
- To cheer you up in difficult times 6: Play Rani Sharim’s two-player games of life, read Maya Bar-Hillel presentation on catching lies with statistics, and more.
- To cheer you up in difficult times 5: A New Elementary Proof of the Prime Number Theorem by Florian K. Richter
- To cheer you up in difficult times 4: Women In Theory present — I will survive
- To cheer you up in difficult times 3: A guest post by Noam Lifshitz on the new hypercontractivity inequality of Peter Keevash, Noam Lifshitz, Eoin Long and Dor Minzer
- Harsanyi’s Sweater

### Top Posts & Pages

- To cheer you up in difficult times 9: Alexey Pokrovskiy proved that Rota’s Basis Conjecture holds asymptotically
- Test Your Intuition (27) about the Alon-Tarsi Conjecture
- Updates and plans III.
- To Cheer you up in Difficult Times 8: Nathan Keller and Ohad Klein Proved Tomaszewski's Conjecture on Randomly Signed Sums
- To cheer you up in difficult times 7: Bloom and Sisask just broke the logarithm barrier for Roth's theorem!
- Jim Geelen, Bert Gerards, and Geoﬀ Whittle Solved Rota's Conjecture on Matroids
- A sensation in the morning news - Yaroslav Shitov: Counterexamples to Hedetniemi's conjecture.
- Timothy Chow Launched Polymath12 on Rota Basis Conjecture and Other News
- 'Gina Says'

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# Monthly Archives: September 2008

## Extremal Combinatorics III: Some Basic Theorems

. Shattering Let us return to extremal problems for families of sets and describe several basic theorems and basic open problems. In the next part we will discuss a nice proof technique called “shifting” or “compression.” The Sauer-Shelah (-Perles -Vapnik-Chervonenkis) Lemma: (Here we write .) … Continue reading

## New Haven (mainly pictures)

] Yale, New Haven I am back in New Haven which have become my home away from home in the last five years. Cappuccino’S and more – Cedar cross Congress, New Haven. Not only that this name is similar … Continue reading

Posted in Uncategorized
Tagged New Haven, Three dimensional electron microscopy, Yale, Yoel Shkolinsky
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## Annotating Kimmo Eriksson’s Poem

“Start counting her NUMBER OF FACES,” Kimmo Eriksson, Brush up your Björner (2008). The time is right to annotate Kimmo Eriksson’s memorable poem: 1. What are Chip firing games? Many women will find it admirable if you tell her she … Continue reading

## A Diameter Problem (5)

6. First subexponential bounds. Proposition 1: How to prove it: This is easy to prove: Given two sets and in our family , we first find a path of the form where, and . We let with and consider the family … Continue reading

## Diameter Problem (4)

Let us consider another strategy to deal with our diameter problem. Let us try to associate other graphs to our family of sets. Recall that we consider a family of subsets of size of the set . Let us now associate … Continue reading

## Diameter Problem (3)

3. What we will do in this post and and in future posts We will now try all sorts of ideas to give good upper bounds for the abstract diameter problem that we described. As we explained, such bounds apply … Continue reading

Posted in Combinatorics, Convex polytopes, Open problems
Tagged Hirsch conjecture, Linear programming, Quasi-automated proofs
1 Comment

## Oded

I just heard the terrible news that Oded Schramm was killed in a hiking accident. Oded was hiking on Guye Peak near Snoqualmie Pass near Seattle. This is a terrible loss to Oded’s family, and our hearts and thoughts are … Continue reading

## The Prisoner’s Dilemma, Sympathy, and Yaari’s Challenge

Correlation and Cooperation In our spring school devoted to Arrow’s economics, Menahem Yaari gave a talk entitled “correlation and cooperation.” It was about games as a model of people’s behavior, and Yaari made the following points: It is an empirical fact … Continue reading

Posted in Economics, Games, Philosophy, Rationality
Tagged Cooperation, Correlation, Prisoner dilemma
5 Comments