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bio website gilkalai.wordpress.com
location Jerusalem
age 59
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Professor of Mathematics at the Hebrew University of Jerusalem and at Yale University

Nov
9
revised How Does Random Noise Typically Look?
added 351 characters in body
Nov
9
comment How Does Random Noise Typically Look?
Thanks, Greg. Right. This is a question where the notion of random operation is rather clear in the quantum case (but never mind if this does not ring a bell) and not clear (to me) for the classic/digital case. I agree that random permutation for 0-1 strings of length n is not necessarily the right analog for random unitary operator on the space of n qubits but part of the question is to proposes the "right" analog.
Nov
9
asked How Does Random Noise Typically Look?
Nov
9
comment The Sylvester Gallai Theorem and Sections of Varieties with “Simple Topology”.
For example; suppose you have a 2 dimensional real algebraic variety V embedded in a high dimensional space (but not in any subspace). Can you find a plane L whose intersection with V affinely span V and belongs to one of a small number of homotopy type?
Nov
9
revised Why do functions in complex analysis behave so well? (as opposed to functions in real analysis)
added 270 characters in body
Nov
9
comment The Sylvester Gallai Theorem and Sections of Varieties with “Simple Topology”.
Thanks, Joe. I corrected it now.
Nov
9
revised The Sylvester Gallai Theorem and Sections of Varieties with “Simple Topology”.
added 21 characters in body
Nov
8
comment Something like mathoverflow in other sciences
I remember there where discussion forums on physics and maybe also on math but I do nt remember the details. the stackexchanges forums on physics and science are still rather undeveloped.
Nov
8
asked The Sylvester Gallai Theorem and Sections of Varieties with “Simple Topology”.
Nov
8
comment When to pick a basis?
"For example, one might define the trace of a matrix to be the sum of the diagonal elements, but many mathematicians would never consider such a definition since it presupposes a choice of basis." This <b> is </b> the standard definition of trace. I am not aware of a single mathematician who would <i> never </i> consider such a definition.
Nov
8
comment Analogue of Sperner's lemma for Lefschetz theorem?
BTW, while it is true that Lefschetz theorem implies Brouwer's theorem this implication relies on homology theory that Sperner's lemma avoids. Once the homology machinary is at hand, in some sense, Lefschetz theorem is a simple linear algebra fact about chain complexes for which we can expect "easier" combinatorial analogs than sperner's lemma.
Nov
8
revised f(f(x))=exp(x)-1 and other functions “just in the middle” between linear and exponential.
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Nov
8
awarded  Commentator
Nov
8
awarded  Editor
Nov
8
comment Describe a topic in one sentence.
This is a very good question, but to be useful and not just fun one should look critically at many of the answers below.
Nov
8
comment Describe a topic in one sentence.
This applies to many other areas as well.
Nov
8
answered Analogue of Sperner's lemma for Lefschetz theorem?
Nov
8
revised Something like mathoverflow in other sciences
added 313 characters in body
Nov
7
accepted f(f(x))=exp(x)-1 and other functions “just in the middle” between linear and exponential.
Nov
7
answered Can one make Erdős's Ramsey lower bound explicit?