The optimal strategy for symmetric rendezvous search on K3

Richard Weber

Published 2009-06-30Version 1

In the symmetric rendezvous search game played on Kn (the completely connected graph on n vertices) two players are initially placed at two distinct vertices (called locations). The game is played in discrete steps and at each step each player can either stay where he is or move to a different location. The players share no common labelling of the locations. They wish to minimize the expected number of steps until they first meet. Rendezvous search games of this type were first proposed by Steve Alpern in 1976. They are simple to describe, and have received considerable attention in the popular press as they model problems that are familiar in real life. They are notoriously difficult to analyse. Our solution of the symmetric rendezvous game on K3 makes this the first interesting game of its type to be solved, and establishes a 20 year old conjecture that the Anderson-Weber strategy is optimal.