Fox, Jacob


Separators in string graphs ★★

Author(s): Fox; Pach; Tóth

Conjecture   Every string graph with $ m $ edges has a separator of size $ O(\sqrt{m}) $.

Keywords: separator; string graphs

Complete bipartite subgraphs of perfect graphs ★★

Author(s): Fox

Problem   Let $ G $ be a perfect graph on $ n $ vertices. Is it true that either $ G $ or $ \bar{G} $ contains a complete bipartite subgraph with bipartition $ (A,B) $ so that $ |A|, |B| \ge n^{1 - o(1)} $?

Keywords: perfect graph

Long rainbow arithmetic progressions ★★

Author(s): Fox; Jungic; Mahdian; Nesetril; Radoicic

For $ k\in \mathbb{N} $ let $ T_k $ denote the minimal number $ t\in \mathbb{N} $ such that there is a rainbow $ AP(k) $ in every equinumerous $ t $-coloring of $ \{ 1,2,\ldots ,tn\} $ for every $ n\in \mathbb{N} $

Conjecture   For all $ k\geq 3 $, $ T_k=\Theta (k^2) $.

Keywords: arithmetic progression; rainbow

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