Unbeatable Imitation

TL;DR

The paper demonstrates that in many symmetric two-player games, the simple 'imitate-the-best' strategy is nearly unbeatable, except in specific rock-scissors-paper type games, highlighting its robustness across various economic and strategic scenarios.

Contribution

It provides necessary and sufficient conditions under which imitation is unbeatable, establishing its effectiveness in a wide range of symmetric games.

Findings

Imitate-the-best is nearly unbeatable in many symmetric games.

It can only be significantly beaten in rock-scissors-paper type games.

In common economic scenarios, imitation performs robustly.

Abstract

We show that for many classes of symmetric two-player games, the simple decision rule "imitate-the-best" can hardly be beaten by any other decision rule. We provide necessary and sufficient conditions for imitation to be unbeatable and show that it can only be beaten by much in games that are of the rock-scissors-paper variety. Thus, in many interesting examples, like 2x2 games, Cournot duopoly, price competition, rent seeking, public goods games, common pool resource games, minimum effort coordination games, arms race, search, bargaining, etc., imitation cannot be beaten by much even by a very clever opponent.