Actions in a multi-agent setting have complex characteristics. They may not only affect the real world, but also affect the knowledge and beliefs of agents in the world. In many cases, the effect on the beliefs or knowledge of an agent is not due to that agent actively doing some actions, but could be simply the result of that agent’s perspective in terms of where it is looking. In dynamic epistemic logic (DEL), such multi-agent actions are expressed as complex constructs or as Kripke model type structures. This paper uses the multi-agent action language mA+ to show how one can take advantage of some of the perspective fluents of the world to model com- plex actions, in the sense of DEL, as simple action sequences. The paper describes several plan modules using such actions. Such plan modules will be helpful in planning for belief and knowledge goals in a multi-agent setting, as planning from scratch would often be prohibitively time consuming.

The paper proposes a condition for preserving the KD45 property of a Kripke model when a sequence of update models is applied to it. The paper defines the notions of a primitive update model and a semi-reflexive KD45 (or sr-KD45) Kripke model. It proves that updating a sr-KD45 Kripke model using a primitive update model results in a sr-KD45 Kripke model, i.e., a primitive update model preserves the properties of a sr-KD45 Kripke model. It shows that several update models for modeling well-known actions found in the literature are primitive. This result provides guarantees that can be useful in presence of multiple applications of actions in multi-agent system (e.g., multi-agent planning).