Abstract
Whether the so-called Tag System can support to emerge cooperation is investigated concerned on 2 × 2 games. As the Tag System, what Riolo et al. (2001) proposed is assumed fundamentally, in which an agent has both Tag and Tol defined by [0,1] real numbers. Tol is a tolerance to recognize an opponent as a company. Both Tag and Tol are assumed to be evolving. Results show that tag's effectiveness depends on whether we allow AllD strategy in the system. If we allow AllD that implies Green Beard Effect does not work in the system, following things are implied; (1) the tag's effectiveness is meager than Riolo et al. reported, (2) Tag System can bring significant Alternating Reciprocity than the analytic solution in a Leader game; (3) the system using 2D tag space is more effectively support a cooperation that the usual Tag System.
