We experimentally study the effect of a third person enforcement on a one-shot prisoner’s dilemma game played by two persons, with whom the third person plays repeated prisoner’s dilemma games. We find that when the third person can observe these two persons’ play, the possibility of the...

We theoretically study the effect of a third person enforcement on a one-shot prisoner’s dilemma game played by two persons, with whom the third person plays repeated prisoner’s dilemma games. We find that the possibility of the third person’s future punishment causes them to cooperate in...

Goods whose benefits increase as the number of users increases, such as fax machines and electric cars, are called "network products," and their related effects are called "network externalities." The diffusion of network products is hampered by private or incomplete information because players...