Balanced Online Ramsey Games in Random Graphs

Anupam Prakash, Reto Spöhel, Henning Thomas


Consider the following one-player game. Starting with the empty graph on $n$ vertices, in every step $r$ new edges are drawn uniformly at random and inserted into the current graph. These edges have to be colored immediately with $r$ available colors, subject to the restriction that each color is used for exactly one of these edges. The player's goal is to avoid creating a monochromatic copy of some fixed graph $F$ for as long as possible.

We prove explicit threshold functions for the duration of this game for an arbitrary number of colors $r$ and a large class of graphs $F$. This extends earlier work for the case $r=2$ by Marciniszyn, Mitsche, and Stojaković. We also prove a similar threshold result for the vertex-coloring analogue of this game.

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