- 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
- Next Week in Jerusalem: Special Day on Quantum PCP, Quantum Codes, Simplicial Complexes and Locally Testable Codes
- Happy Birthday Ervin, János, Péter, and Zoli!
- My Mathematical Dialogue with Jürgen Eckhoff
- Test Your Intuition (23): How Many Women?
- Happy Birthday Richard Stanley!
Top Posts & Pages
- Believing that the Earth is Round When it Matters
- The Kadison-Singer Conjecture has beed Proved by Adam Marcus, Dan Spielman, and Nikhil Srivastava
- The Ultimate Riddle
- Analysis of Boolean Functions
- Jim Geelen, Bert Gerards, and Geoﬀ Whittle Solved Rota's Conjecture on Matroids
- Meeting with Aram Harrow, and my Lecture on Why Quantum Computers Cannot Work.
- Amazing: Peter Keevash Constructed General Steiner Systems and Designs
- Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
- Two Math Riddles
Monthly Archives: May 2013
Joram Lindenstrauss 1936-2012 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
The news in brief Andriy V. Bondarenko proved in his remarkable paper The Borsuk Conjecture for two-distance 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
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
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! French-Isreali Meeting … Continue reading
You run a single-item 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
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
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
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
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.
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