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Bourgain's Proof of Katznelson Furstenberg weiss theorem   Message List  
Reply | Forward Message #384 of 455 |
Re: [harmonic] Bourgain's Proof of Katznelson Furstenberg weiss theorem

Dear Sir,

Thanks for your kind reply and references.

Indeed the paper you mentioned (Distance sets corresponding to convex bodies ) contains a detailed step by step proof of FKW theorem by Bourgain.

However my question was regarding the farther generalization of this theorem in 2-dimension  in Bourgain's paper. My question was regarding that.

Specifically
 
After proving the FKW theorem he writes (Page 309 last para) as a remark:-

\begin{remark}
Combined with the results on the spherical maximal function in the plane, Theorem 1 can be improved as follows:
\end{remark}

\begin{theorem}"\

If $A \subset \R^2$, $\delta(A) >0 $, there exists $l = l(A)$ such that whenever $l_1 > l$ there is a point $x \in A$
fulfilling the condition $\{ |x-y|; y\in A \} \supset [l,l_1] $

\end{theorem}

my difficulty is with this part.

I would be happy if you could explain the outline of the proof.

Thanking you

Sincerely
Debashish



--- On Sat, 7/12/08, Alex Iosevich <iosevich@...> wrote:
From: Alex Iosevich <iosevich@...>
Subject: Re: [harmonic] Bourgain's Proof of Katznelson Furstenberg weiss theorem
To: harmonicanalysis@yahoogroups.com
Date: Saturday, July 12, 2008, 4:32 AM

Dear Debashish,
 
A very clear and complete proof of what you are asking about can be found in a paper by Mihalis Kolountzakis ( Kolountzakis, M. N. Distance sets corresponding to convex bodies. Geom. Funct. Anal. 14 (2004), no. 4, 734--744). You can also get this paper directly from Mihalis' web page at the University of Crete). For a finite geometric version, you can take a look at  Iosevich, A.; Rudnev, M. Erdös distance problem in vector spaces over finite fields. Trans. Amer. Math. Soc.. 359 (2007), no. 12, 6127--6142 and Hart, Derrick; Iosevich, Alex Ubiquity of simplices in subsets of vector spaces over finite fields. Anal. Math. 34 (2008), no. 1, 29--38.
 
Best regards,
 
Alex Iosevich
Department of Mathematics
University of Missouri-Columbia
Columbia, Missouri, 65211 USA


 
On 7/11/08, noone <d_bose2000@yahoo. com> wrote:

While reading the book Geometric Discrepancy I came across the proof
by Bourgain of Furstenberg, Katznelson and Weiss Theorem regarding the
un-avoidability of all large distances in a set with positive
asymptotic density. Which I managed to follow ...

Having gone through that I got hold of the original paper by Bourgain
where there is stronger version claiming the existence of some r,
such that given any s>r there is a x \in A s.t \forall t \in [r,s]
there exist y \in A with |x-y|= t .

I am unable to figure out how the proof works ...

Can you kindly give me a hint or direct me to a reference where I can
find more details.

Thanking you
Debashish




--
I am constantly amazed by man's inhumanity to man

Primo Levi



Sat Jul 12, 2008 3:25 pm

d_bose2000
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Message #384 of 455 |
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While reading the book Geometric Discrepancy I came across the proof by Bourgain of Furstenberg,Katznelson and Weiss Theorem regarding the un-avoidability of...
noone
d_bose2000
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Jul 11, 2008
7:08 pm

Dear Debashish, A very clear and complete proof of what you are asking about can be found in a paper by Mihalis Kolountzakis ( Kolountzakis, M. ...
Alex Iosevich
aiosevich
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Jul 12, 2008
11:33 am

Dear Sir, Thanks for your kind reply and references. Indeed the paper you mentioned (Distance sets corresponding to convex bodies ) contains a detailed step by...
bose D
d_bose2000
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Jul 22, 2008
8:39 pm
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