Finding a Low-dimensional Piece of a Set of Integers

We show that a finite set of integers A subset of Z with |A + A| = K|A| contains a large piece X subset of A with Freiman dimension O(log K), where large means |A|/|X| << exp(O(log(2) K)). This can be thought of as a major quantitative improvement on Fre. iman's dimension lemma; or as a "weak" Freiman-Ruzsa theorem with almost polynomial bounds. The methods used, centred around an "additive energy increment strategy", differ from the usual tools in this area and may have further potential. Most of our argument takes place over F-2(n), which is itself curious. There is a possibility that the above bounds could be improved, assuming sufficiently strong results in the spirit of the Polynomial Freiman Ruzsa Conjecture over finite fields.