Skip to main content

All Questions

Filter by
Sorted by
Tagged with
59 votes
2 answers
4k views

For a finite set A of positive reals, prove that the set A + A - A contains at least as many positive as negative elements

I am currently working on a proof that would need to use the following theorem that I cannot prove: "Let $A$ be a finite set of positive real numbers. Then, the set $A + A - A$ contains at least ...
Timo Reichert's user avatar
4 votes
2 answers
427 views

How big must the sumset $A+A$ be if $A$ satisfies no translation-invariant equations of low height?

Suppose $A$ is a finite subset of an abelian group. If there is no solution to $ma+nb=(m+n)c$ with $0\leq m,n\leq M$, can we bound $|A+A|$ from below? I am interested if one can obtain bounds much ...
deadcat's user avatar
  • 41
3 votes
3 answers
749 views

Is the sumset or the sumset of the square set always large?

Let A be a finite subset of $\mathbb{N}$, $\mathbb{R}$, or a sufficiently small subset of $\mathbb{F}_{p}$. Do we have a lower bound of the form $|A|^{1+\delta}$ on the following quantity: $$\max (|\...
Mark Lewko's user avatar