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In Tao and Vu's Additive Combinatorics, it is mentioned that "if we replace the additive set $A$ by a larger set, such as $A+B$, $A+A+A$, or $2A - 2A$, then one can locate significantly larger progressions inside these sets..." Thus it would see quite interesting to investigate under what circumstances a given set is of the forms above.

On one note, there has been some work done to investigate what $B$ could be if $A, A+B$ are known, namely the complementary base problem. In particular, Vu proved in 2002 that if $\mathcal{P}$ is the set of primes, then there exists a set $B$ such that $|B \cap [1,n]| = O(\log n)$ and the set {$p + b : p \in \mathcal{P}, b \in B$} $= \mathbb{N} \setminus C$, where $C$ is a finite set.

My question is, if we know about a set $S$, are there any methods to detect if it contains or is equal to a set of the form $A+B, A+A+A, 2A-2A$ etc.?

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See my question mathoverflow.net/questions/55303/how-large-can-a-non-sumset-be and Seva's answer for cardinality methods (and the proofs of Alon in the linked paper also give interesting methods for constructing such sumsets) –  Thomas Bloom Feb 26 '11 at 18:05
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Almost nothing is known about this, although the question is certainly not new; see Problem 4.11 of this joint paper of Ernie Croot and myself.

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