A Nash equilibrium is a profile where no player has an incentive to unilaterally deviate from his strategy choice. In other words, a Nash equilibrium is a combination of (possibly mixed) strategies such that they all play their best response given the strategy choices of the others. Again, \((t,l)\) and \((b,r)\) are the only pure-strategy equilibria of the above coordination game. Nash equilibrium, and its numerous refinements, is arguably the game theoretical solution concept that has been most used in game theory (Aumann &amp; Hart 1994) and philosophy (e.g., famously in Lewis 1969).