A fixed point characterization of the dominancesolvability of lattice games with strategic substitutes

This note demonstrates that a lattice game with strategic substitutes is dominancesolvable if and only if there exists a unique fixed point of the function that results from an iteration of the best response function. This finding complements a result of Milgrom and Roberts’ (1990) by which a lattice game with strategic complements is dominance-solvable if and only if there exists a unique Nash equilibrium. We illustrate our main result by an application to a model of Cournot outcomecompetition.