Within a general semimartingale framework, we study the relationship between collective market efficiency and individual rationality. We derive a necessary and sufficient condition for the existence of (possibly zero-sum) exchanges among agents that strictly increase their indirect utilities and characterize this condition in terms of the compatibility between agents' preferences and collective pricing measures. The framework applies to both continuous- and discrete-time models and clarifies when cooperation leads to a strict improvement in each participating agent's indirect utility.

翻译：在一般半鞅框架下，我们研究了集体市场效率与个体理性之间的关系。我们推导出了代理人之间（可能为零和）交换存在的充分必要条件，这种交换严格提高了他们的间接效用，并用代理人的偏好与集体定价测度之间的相容性来刻画该条件。该框架适用于连续时间和离散时间模型，并阐明了合作何时会使每个参与代理人的间接效用得到严格改善。