  Both classical and quantum version of two models of price competition in
duopoly market, the one is realistic and the other is idealized, are
investigated. The pure strategy Nash equilibria of the realistic model exists
under stricter condition than that of the idealized one in the classical form
game. This is the problem known as Edgeworth paradox in economics. In the
quantum form game, however, the former converges to the latter as the measure
of entanglement goes to infinity.
