Communication within groups of agents has been lately the focus of research in dynamic epistemic logic (DEL). This paper studies a recently introduced form of partial (more precisely, topic-based) communication. This type of communication allows for modelling scenarios of multi-agent collaboration and negotiation, and it is particularly well-suited for situations in which sharing all information is not feasible/advisable. After presenting results on invariance and complexity of model checking, the paper compares partial communication to public announcements, probably the most well-known type of communication in DEL. It is shown that the settings are, update-wise, incomparable: there are scenarios in which the effect of a public announcement cannot be replicated by partial communication, and vice versa. Then, the paper shifts its attention to strategic topic-based communication. It does so by extending the language with a modality that quantifies over the topics the agents can `talk about'. For this new framework, it provides a complete axiomatisation, showing also that the new language's model checking problem is PSPACE-complete. The paper closes showing that, in terms of expressivity, this new language of arbitrary partial communication is incomparable to that of arbitrary public announcements.

翻译：群体内智能体间的通信近年来成为动态认知逻辑（DEL）研究的焦点。本文研究一种近期引入的部分（更精确地说，基于主题的）通信形式。这种通信类型允许对多智能体协作与协商场景进行建模，尤其适用于无法/不宜共享全部信息的情境。在给出模型检验的不变性与复杂性结果后，本文将部分通信与公开宣告（DEL中最广为人知的通信类型）进行比较。研究表明，从更新视角看，二者不可比较：存在公开宣告的效果无法通过部分通信复现的情形，反之亦然。随后，本文将关注点转向策略性基于主题的通信：通过扩展语言引入一个量化智能体可"谈论"主题的模态算子。针对这一新框架，本文提供了完备的公理化系统，并证明该新语言的模型检验问题为PSPACE-完全。最后，本文证明在表达能力层面，这种新的任意部分通信语言与任意公开宣告语言不可比较。