We define a model of interactive communication where two agents with private types can exchange information before a game is played. The model contains Bayesian persuasion as a special case of a one-round communication protocol. We define message complexity corresponding to the minimum number of interactive rounds necessary to achieve the best possible outcome. Our main result is that for bilateral trade, agents don't stop talking until they reach an efficient outcome: Either agents achieve an efficient allocation in finitely many rounds of communication; or the optimal communication protocol has infinite number of rounds. We show an important class of bilateral trade settings where efficient allocation is achievable with a small number of rounds of communication.

中文翻译：

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双边贸易中的互动交流

我们定义了一个交互通信模型，其中两个具有私有类型的代理可以在玩游戏之前交换信息。该模型包含作为单轮通信协议的特例的贝叶斯说服。我们定义了对应于实现最佳可能结果所需的最小交互轮数的消息复杂度。我们的主要结果是，对于双边贸易，代理人在达成有效结果之前不会停止谈话：任一代理人在有限多轮通信中实现有效分配；或者最佳通信协议具有无限轮数。我们展示了一类重要的双边贸易环境，通过少量的交流就可以实现有效的分配。