中文摘要：

本文提出一个基于无知的群组宣告逻辑，该逻辑是带有宣告算子的无知逻辑加上一个基于无知的群组宣告算子的扩展，用以表达群组中的每个主体宣告他们各自的无知后什么东西为真。我们对比这一逻辑和文献中相关逻辑的相对表达力，并研究该逻辑的框架可定义性问题。另外，我们也提出一个公理化系统并证明它的完全性。

英文摘要：

In this paper, we propose a group announcement logic for ignorance, which is an extension of the logic of ignorance with announcements and a group announcement operator for ignorance, expressing what is true after each agent in the group announces his/her own ignorance. We compare the relative expressivity of this logic and some relevant variations. We also investigate the frame definability issue of this logic. Besides, we present an axiomatization and demonstrate its completeness.