Unsolved problems in visibility graphs of points, segments, and polygons
ACM Computing Surveys (CSUR)
Hi-index | 0.05 |
Let A ⊆ Z2 be a finite set of lattice points and let |A| =n. We prove that if A does not contain any three collinear points, then |A ± A| ≥ n(log n)δ. Here δ can be every positive absolute constant δ ≤ 1/8. This lower bound provides an answer to an old question of Freiman. Some further related questions on non-averaging sets of integers are posed and discussed.