The condition is derived for Friedman 's trigger strategy to sustaina collusive market equilibrium as a noncooperative Nash equilibriumgiven subjective beliefs as to the antitrust authority's ability of suc-cesfully dissolving the illegal cartel.

To account for the illegal nature of price-fixing agreements, detection probabilities are introduced in a dynamic oligopoly. It follows that for a trigger strategy to sustain a non-cooperative collusive equilibrium as a SPNE both the discount rate and all per-period detection probabilities have...