##### Department of Mathematics,

University of California San Diego

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### Math 269 - Combinatorics

## Jozsef Solymosi

#### UCSD

## On a problem of Ron Graham

##### Abstract:

We give a quantitative proof that forsufficiently large N=N(c), every subset of$[N]^2$ of size at least $cN^2$ contains a square, i.e. four pointswith coordinates {(a,b),(a+d,b),(a,b+d),(a+d,b+d)}.

Host:

### October 15, 2002

### 4:00 PM

### AP&M 7321

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