Recent Comments

Recent Posts
 First third of my ICM2018 paper – Three Puzzles on Mathematics, Computation and Games. Corrections and comments welcome
 Preview: The solution by Keller and Lifshitz to several open problems in extremal combinatorics
 Basic Notions Seminar is Back! Helly Type Theorems and the Cascade Conjecture
 My Very First Book “Gina Says”, Now Published by “World Scientific”
 Itai Benjamini: Coarse Uniformization and Percolation & A Paper by Itai and me in Honor of Lucio Russo
 AfterDinner Speech for Alex Lubotzky
 Boaz Barak: The different forms of quantum computing skepticism
 Bálint Virág: Random matrices for Russ
 Test Your Intuition 33: The Great Free Will Poll
Top Posts & Pages
 First third of my ICM2018 paper  Three Puzzles on Mathematics, Computation and Games. Corrections and comments welcome
 Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
 Preview: The solution by Keller and Lifshitz to several open problems in extremal combinatorics
 Elchanan Mossel's Amazing Dice Paradox (your answers to TYI 30)
 TYI 30: Expected number of Dice throws
 Can Category Theory Serve as the Foundation of Mathematics?
 If Quantum Computers are not Possible Why are Classical Computers Possible?
 Eran Nevo: gconjecture part 4, Generalizations and Special Cases
 Polymath 10 Emergency Post 5: The ErdosSzemeredi Sunflower Conjecture is Now Proven.
RSS
Monthly Archives: May 2013
Joram’s Memorial Conference
Joram Lindenstrauss 19362012 This week our local Institute of Advanced Study holds a memorial conference for Joram Lindenstrauss. Joram was an immensely powerful mathematician, in terms of originality and conceptual vision, in terms of technical power, in terms of courage to confront … Continue reading
Andriy Bondarenko Showed that Borsuk’s Conjecture is False for Dimensions Greater Than 65!
The news in brief Andriy V. Bondarenko proved in his remarkable paper The Borsuk Conjecture for twodistance sets that the Borsuk’s conjecture is false for all dimensions greater than 65. This is a substantial improvement of the earlier record (all dimensions … Continue reading
Why is mathematics possible?
Spectacular advances in number theory Last weeks we heard about two spectacular results in number theory. As announced in Nature, Yitang Zhang proved that there are infinitely many pairs of consecutive primes which are at most 70 million apart! This is a sensational achievement. … Continue reading
Dan Mostow on Haaretz and Other Updates
Enlightenment at a red traffic light Wolf Prize laureate Prof. George Daniel Mostow made his greatest scientific breakthrough while driving. Haaretz tells the story of how Dan Mostow reached his breakthrough known as Mostow’s rigidity theorem. Congratulations, Dan! FrenchIsreali Meeting … Continue reading
Test Your Intuition (21): Auctions
You run a singleitem sealed bid auction where you sell an old camera. There are three bidders and the value of the camera for each of them is described by a certain (known) random variable: With probability 0.9 the value … Continue reading
Posted in Economics, Games, Test your intuition
Tagged Auctions, Roger Myerson, Test your intuition
4 Comments
Oz’ Balls Problem: The Solution
A commentator named Oz proposed the following question: You have a box with n red balls and n blue balls. You take out each time a ball at random but, if the ball was red, you put it back in the box and take out … Continue reading
Posted in Probability, Test your intuition
Tagged Erosion, J. F. C. Kingman, Probability, S. E. Volkov
1 Comment
Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
Yeshu Kolodni and Lord Kelvin The question In 1862, the physicist William Thomson (who later became Lord Kelvin) of Glasgow published calculations that fixed the age of Earth at between 20 million and 400 … Continue reading
Posted in Geology, Physics, Test your intuition
7 Comments
Test your Intuition/Knowledge: What was Lord Kelvin’s Main Mistake?
The age of the earth (Thanks to Yeshu Kolodny) We now know that the age of the earth is 4.54±1% Billion years. From Wikipedea: In 1862, the physicist William Thomson (who later became Lord Kelvin) of Glasgow published calculations that … Continue reading
Posted in Controversies and debates, Geology, Physics, Test your intuition
Tagged Earth, Geology, Lord Kelvin, Test your intuition
Leave a comment
Indian Crested Porcupine
For a few days we had an Indian Crested Porcupine (דורבן) in our garden. It ate all the flowers and dug an impressive array of tunnels.
New Ramanujan Graphs!
Margulis’ paper Ramanujan graphs were constructed independently by Margulis and by Lubotzky, Philips and Sarnak (who also coined the name). The picture above shows Margulis’ paper where the graphs are defined and their girth is studied. (I will come back to the question … Continue reading
Posted in Algebra and Number Theory, Combinatorics, Open problems
Tagged Ramanujan graphs
10 Comments