# Calendar

Discrete Math

## Cooperative colorings

#### Ron Aharoni, Technion

Location:  HILL 705
Date & time: Monday, 25 September 2017 at 2:00PM - 3:00PM

Abstract:  Given graphs $$G_1, ldots, G_k$$ on the same vertex set $$V$$, a {em cooperative coloring} is a choice of an independent set $$I_j$$ in each  $$G_j$$, such that $$bigcup_{j le k}I_j=V$$. When all $$G_i$$s are the same graph, this is the familiar notion of $$k$$-coloring. What is the analogue of the fact that the coloring number of a graph $$G$$ is no larger than $$Delta(G)+1$$? A sample result: three cycles have a cooperative coloring.

Joint works with Berger, Chudnovsky, Holzman, Jiang and Spr"ussel.