Contest Dynamics Between Cooperation and Exploitation

TL;DR

This paper extends the Prisoner's Dilemma to include competitive fighting using contest theory, revealing complex dynamics where cooperation can persist alongside competition in structured populations.

Contribution

It introduces a new model combining cooperation, defection, and fighting based on resource-dependent contest success, expanding understanding of social behavior evolution.

Findings

Cooperation and competition coexist under certain resource conditions.

Fighters delay defector dominance, promoting cooperation.

Rich phase diagrams show expanded cooperation regimes.

Abstract

Cooperation and competition are fundamental forces shaping both natural and human systems, yet their interplay remains poorly understood. The Prisoner's Dilemma Game (PDG) has long served as a foundational framework in Game Theory for studying cooperation and defection, yet it overlooks explicit competitive interactions. Contest Theory, in turn, provides tools to model competitive dynamics, where success depends on the investment of resources. In this work, we bridge these perspectives by extending the PDG to include a third strategy, fighting, governed by the Tullock contest success function, where success depends on relative resource investments. This model, implemented on a square lattice, examines the dynamics of cooperation, defection, and competition under resource accumulation and depletion scenarios. Our results reveal a rich phase diagram in which cooperative and competitive strategies coexist under certain critical resource investments, expanding the parameter space for cooperation beyond classical limits. Fighters delay the dominance of defectors by mediating interactions, expanding the conditions under which cooperation persists. This work offers new insights into the evolution of social behaviors in structured populations, bridging cooperation and competition dynamics.