A set S of integers is sum-free if the equation a+b=c has no solution with a,b,c in S. Cameron and Erdos conjectured that the number of sum-free subsets of {1,2,...,n} is bounded above by c2^{N/2} for some c>0. This is the first of two lectures on Ben Green's proof of this conjecture.

Zeljka Ljujic