Gideon Schechtman

The UGC hardness threshold of the Lp Grothendieck problem (2009)

Guy Kindler, Assaf Naor, Gideon Schechtman

Abstract For p> = 2 we consider the problem of, given an n * n matrix A = (ai j) whose diagonal entries vanish,approximating in polynomial time the number

Diamond (2009)

William B. Johnson, Gideon Schechtman

graphs and super-reflexivity ∗

Optp (A) ≔ max ai jxixj: (x1,..., xn) ∈ R (2009)

Guy Kindler, Assaf Naor, Gideon Schechtman

For p ≥ 2 we consider the problem of, given an n × n matrix A = (ai j) whose diagonal entries vanish, approximating in polynomial time the number n�

The UGC (2008)

Guy Kindler, Assaf Naor, Gideon Schechtman

hardness threshold of the ℓp Grothendieck problem

Finite dimensional subspaces of L p (2007)

William B. Johnson, Gideon Schechtman

We discuss the finite dimensional structure theory of L p; in particular, the theory of restricted invertibility and classification of subspaces of # n p. Contents 1

An "isomorphic" Version Of Dvoretzky's Theorem, II (2007)

Vitali D. Milman, Gideon Schechtman

A different proof is given to the result announced in [MS2]: For each 1 k ! n we give an upper bound on the minimal distance of a k-dimensional subspace of an arbitrary n-dimensional normed space to...

An "isomorphic" Version Of Dvoretzky's Theorem (2007)

Vitali D. Milman, Gideon Schechtman

For each 1 k ! n we give an upper bound on the minimal distance of a k-dimensional subspace of an arbitrary n-dimensional normed space to the Hilbert space of dimension k. The result is best possible...

An Editorial Comment on the Preceding Paper (2007)

Gideon Schechtman Would, Gideon Schechtman

)j kx \Gamma yk 1 extend it to a function F on IR n with the same Lip constant with respect to k \Delta k 1 and note that jF (x) \Gamma F (y)j p nkx \Gamma yk 2 . Put S = P jx i j; T = P jy i j....

Block bases of the Haar system as complemented subspaces of L p, 2! p! 1 (2007)

Dvir Kleper, Gideon Schechtman

It is shown that the span of fa i h i \Phi b i e i g n i=1, where fh i g is the Haar system in L p and fe i g the canonical basis of ` p, is well isomorphic to a well complemented subspace of L p; 2!...

y (2007)

William B. Johnson, Joram Lindenstrauss, David Preiss, Gideon Schechtman

mappings between infinite dimensional Banach spaces

Very tight embeddings of subspaces of L p, 1 p 2, into n (2007)

William B. Johnson, Gideon Schechtman

We prove that for 1 p < r < 2, every n-dimensional subspace E of L r , in particular ` r , well-embeds into ` p for some m (1 + )n, where \well" depends on p, r, and the arbitrary > 0,...

Graphs with Tiny Vector Chromatic Numbers and Huge Chromatic Numbers (Extended Abstract) (2007)

Uriel Feige, Michael Langberg, Gideon Schechtman

Uriel Feige Michael Langberg Gideon Schechtman Department of Computer Science and Applied Mathematics Weizmann Institute of Science, Rehovot 76100 ffeige,mikel,gideong@wisdom.weizmann.ac.il Abstract...

Asymptotic Geometric Analysis, Fall 2006 ∗ (2007)

Gideon Schechtman

The course will deal with convex symmetric bodies in R n. In the first few lectures we will formulate and prove Dvoretzky theorem, Theorem 1.2.

Extremal configurations for moments of sums of independent positive random variables (2007)

Gideon Schechtman

We find the extremal configuration for the p-moment of sums of independent positive random variables while constraining the sum of the expectations of the random variables and the sum of their...

Planar earthmover is not in l1 (2006)

Assaf Naor, Gideon Schechtman

We show that any L1 embedding of the transportation cost (a.k.a. Earthmover) metric on probability measures supported on the grid {0, 1,..., n} 2 ⊆ R 2 incurs distortion Ω � � log n �. We...

Planar Earthmover is not in $L_1$ (2005)

Naor, Assaf, Schechtman, Gideon

We show that any $L_1$ embedding of the transportation cost (a.k.a. Earthmover) metric on probability measures supported on the grid $\{0,1,...,n\}^2\subseteq \R^2$ incurs distortion...

The shattering dimension of sets of linear functionals (2004)

Mendelson, Shahar, Schechtman, Gideon

We evaluate the shattering dimension of various classes of linear functionals on various symmetric convex sets. The proofs here relay mostly on methods from the local theory of normed spaces and...

The shattering dimension of sets of linear functionals (2004)

Mendelson, Shahar, Schechtman, Gideon

We evaluate the shattering dimension of various classes of linear functionals on various symmetric convex sets. The proofs here relay mostly on methods from the local theory of normed spaces and...

Special orthogonal splittings of $L_1^{2k}$ (2003)

Schechtman, Gideon

We show that for each positive integer $k$ there is a $k\times k$ matrix $B$ with $\pm 1$ entries such that putting $E$ to be the span of the rows of the $k\times 2k$ matrix $[\sqrt{k}I_k,B]$, then...

The shattering dimension of sets of linear functionals (2003)

Shahar Mendelson, Gideon Schechtman

We evaluate the shattering dimension of various classes of linear functionals on various symmetric convex sets. The proofs here relay mostly on methods from the Local Theory of Normed Spaces and...

Lipschitz quotients from metric trees and from Banach spaces containing l1 (2002)

William B. Johnson, Joram Lindenstrauss, David Preiss, Gideon Schechtman

A Lipschitz map f between the metric spaces X and Y is called a Lipschitz quotient map if there is a C> 0 (the smallest such C, the co-Lipschitz constant, is denoted coLip(f), while Lip(f) denotes

Almost Frechet differentiability of Lipschitz mappings between infinite dimensional Banach spaces (2001)

William B. Johnson, Joram Lindenstrauss, David Preiss, Gideon Schechtman

We give several sufficient conditions on a pair of Banach spaces X and Y under which each Lipschitz mapping from a domain in X to Y has, for every #> 0, a point of #-Frechet differentiability....

Gaussian Random Field and the Range of Random Graph Homomorphisms into Z (2001)

The Erwin, Schrödinger International Boltzmanngasse, Itai Benjamini, Gideon Schechtman, Itai Benjamini, Gideon Schechtman

Bounds on the range of random graph homomorphism into Z, and the maximal height difference of the Gaussian random field, are presented. 1

On the optimality of the random hyperplane rounding technique for MAX CUT (2000)

Uriel Feige, Gideon Schechtman

MAX CUT is the problem of partitioning the vertices of a graph into two sets, maximizing the number of edges joining these sets. This problem is NP-hard. Goemans and Williamson proposed an algorithm...

On the optimality of the random hyperplane rounding technique for MAX CUT (2000)

Uriel Feige, Gideon Schechtman

MAX CUT is the problem of partitioning the vertices of a graph into two sets, maximizing the number of edges joining these sets. This problem is NP-hard. Goemans and Williamson proposed an algorithm...

Almost Fréchet differentiability of Lipschitz mappings between infinite dimensional Banach spaces (2000)

William B. Johnson, Joram Lindenstrauss, David Preiss, Gideon Schechtman

We give several sufficient conditions on a pair of Banach spaces X and Y under which each Lipschitz mapping from a domain in X to Y has, for every ffl ? 0, a point of ffl-Fr'echet...

Upper Bounds on the Height Difference of the Gaussian Random Field and the Range of Random Graph Homomorphisms into Z (2000)

The Erwin, Schrodinger International Boltzmanngasse, Itai Benjamini, Itai Benjamini, Gideon Schechtman, Gideon Schechtman

Bounds on the range of random graph homomorphism into Z, and the maximal height dierence of the Gaussian random eld, are presented. 1 Introduction In this note we study the range of two related...

Upper Bounds on the Height Difference of the Gaussian Random Field and the Range of Random Graph Homomorphisms into Z (1999)

Itai Benjamini, Gideon Schechtman

Bounds on the range of random graph homomorphism into Z, and the maximal height difference of the Gaussian random field, are presented. 1 Introduction In this note we study the range of two related...

Concentration, Results and Applications (1999)

Gideon Schechtman

this article we survey many (but not all) of the methods of proof of concentration and approximate isoperimetric inequalities. We tried to concentrate mostly on methods which are quite general or...

Upper Bounds on the Height Difference of the Gaussian Random Field and the Range of Random Graph Homomorphisms into Z (1999)

Itai Benjamini, Gideon Schechtman

Abstract Bounds on the range of random graph homomorphism into Z, and the maximal height difference of the Gaussian random field, are presented.

Hypercontractivity and Comparison of Moments of Iterated Maxima and Minima of Independent Random Variables (1998)

Pawel Hitczenko, Stanislaw Kwapien, Wenbo V. Li, Gideon Schechtman

: We provide necessary and sufficient conditions for hypercontractivity of the minima of nonnegative, i.i.d. random variables and of both the maxima of minima and the minima of maxima for such...

Nonlinear quotients (1997)

Bates, Sean M., Johnson, William B., Lindenstrauss, Joram, Preiss, D., Schechtman, Gideon

New concepts related to approximating a Lipschitz function between Banach spaces by affine functions are introduced. Results which clarify when such approximations are possible are proved and in some...

Banach spaces determined by their uniform structures (1997)

Johnson, William B., Lindenstrauss, Joram, Schechtman, Gideon

Following results of Bourgain and Gorelik we show that the spaces $\ell_p$, $1

A Remarkable Rearrangement Of The Haar System In L_p (1997)

Gideon Schechtman

We introduce a non-standard but, to our opinion natural, order on the initial segments of the Haar system and investigate the isomorphic classification of the linear span, in L p , of block bases,...

On the Best Constants in the Khintchine Inequality (1997)

Johannes Wissel, Joseph Turian, Mentor Arteom, Zvavitch Supervisor, Gideon Schechtman, A P \delta

We show a self-contained new proof for the best Bp constant in the Khintchine Inequality for p > 3 using only elementary calculus.

Hypercontractivity and comparison of moments of iterated maxima and minima of independent random variables (1996)

Hitczenko, P., Kwapień, Stanisław, Li, Wenbo V., Schechtman, Gideon, Schlumprecht, Thomas, Zinn, Joel

We provide necessary and sufficient conditions for hypercontractivity of the minima of nonnegative, i.i.d. random variables and of both the maxima of minima and the minima of maxima for such r.v.'s....

On the Gaussian measure of the intersection of symmetric, convex sets (1996)

Schechtman, Gideon, Schlumprecht, Thomas, Zinn, Joel

The Gaussian Correlation Conjecture states that for any two symmetric, convex sets in n-dimensional space and for any centered, Gaussian measure on that space, the measure of the intersection is...

Banach Spaces Determined By Their Uniform Structures (1996)

William B. Johnson, Joram Lindenstrauss, Gideon Schechtman

Following results of Bourgain and Gorelik we show that the spaces ` p , 1 ! p ! 1, as well as some related spaces have the following uniqueness property: If X is a Banach space uniformly homeomorphic...

Almost Frechet differentiability of Lipschitz maps between infinite dimensional Banach spaces (1995)

William B. Johnson, Joram Lindenstrauss, David Preiss, Gideon Schechtman

We give several sufficient conditions on a pair of Banach spaces X and Y under which each Lipschitz mapping from a domain in X to Y has, for every #> 0, a point of #-Frechet di#erentiability. Most...

Banach spaces with the $2$-summing property (1994)

Arias, Alvaro, Figiel, Tadek, Johnson, William B., Schechtman, Gideon

A Banach space $X$ has the $2$-summing property if the norm of every linear operator from $X$ to a Hilbert space is equal to the $2$-summing norm of the operator. Up to a point, the theory of spaces...

Computing p-summing norms with few vectors (1992)

Johnson, William B., Schechtman, Gideon

It is shown that the p-summing norm of any operator with n-dimensional domain can be well-aproximated using only ``few" vectors in the definition of the p-summing norm. Except for constants...

Factorizations of natural embeddings of l_p^n int L_r (1992)

Figiel, Tadek, Johnson, William B., Schechtman, Gideon

This is a continuation of the paper [FJS] with a similar title. Several results from there are strengthened, in particular: 1. If T is a "natural" embedding of l_2^n into L_1 then, for any...

Remarks on Talagrand's deviation inequality for Rademacher functions (1990)

Johnson, William B., Schechtman, Gideon

Recently Talagrand [T] estimated the deviation of a function on $\{0,1\}^n$ from its median in terms of the Lipschitz constant of a convex extension of $f$ to $\ell ^n_2$; namely, he proved that...

On the volume of the intersection of two $L_p^n$ balls (1989)

Schechtman, Gideon, Zinn, Joel

This note deals with the following problem, the case $p=1$, $q=2$ of which was introduced to us by Vitali Milman: What is the volume left in the $L_p^n$ ball after removing a t-multiple of the...

Contemporary Mathematics (1984)

William B. Johnson, Gideon Schechtman

We discuss the finite dimensional structure theory of L p; in particular, the theory of restricted invertibility and classification of subspaces of ` n p. Contents 1

Finite dimensional subspaces of L_p

William B. Johnson, Gideon Schechtman

this article, we chose to devote this section to describing the change of densities that arise later. It turns out that the framework in which this technique is most naturally used is that of an L p...

The Shattering Dimension of Sets of Linear Functionals

Shahar Mendelson, Gideon Schechtman

We evaluate the shattering dimension of various classes of linear functionals on various symmetric convex sets. This is applied in two di#erent directions. The first is the determination of whether...