~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Outside option在Rubistein的bargaining and  markets 那本书中有讲到，Shapley Value的定义及应用在Rubistein的a course in game theory 最后部分---cooperative game 部分。

An "inside option" is the bargaining offer a player can take.
An "outside option" is a payoff a player can get if bargaining fails. Here, in the context of interstate bargaining, the outside option is the player's payoff if the states go to war.
Generally, the better a player's outside offer is, the better the player's inside offer will be. The idea here is that the player making the offers has to give more to induce the receiver to accept.

外部选择是指契约外的潜在交易收益；内部选择指的是契约双方可以确定的交易条款。