# Graduate Student / Postdoc Seminar

#### Epistemic Logic and Dynamics of Information Change

**Speaker:**
Andreas Witzel, Courant

**Location:**
Warren Weaver Hall 1302

**Date:**
Friday, October 21, 2011, 1 p.m.

**Synopsis:**

Epistemic logic is the formal study of reasoning about knowledge and beliefs. Starting from a philosophical motivation of defining exactly what it means to "know" something, epistemic logic has classically focused on describing static situations. Later, the focus was extended to encompass changing information, raising a plethora of new questions. Comparatively recently, a formalism was developed that represents knowledge (or uncertainty) about events in much the same way as knowledge (or uncertainty) about situations. This formalism, called Dynamic Epistemic Logic, allows specifying situations and events in a uniform and modular way, which makes it interesting for AI applications.

In my talk, I will first give an introduction to modelling knowledge and beliefs using epistemic modal logic, briefly reviewing some underlying intuitions and philosophical foundations of classical single- and multi-agent epistemic logic.

Then, I will present Dynamic Epistemic Logic, a conceptually simple, but surprisingly rich framework for modeling the dynamics of information change, which has become an active research area within modal logic.

Due its modularity, the framework also seems to lend itself to applications in AI. For example, one can envision a vitual world keeping track of its inhabitants' knowledge about facts and about each other, and enabling agents to respond adequately to events that change their knowledge states; or automated planning using epistemic conditions, effects, and goals. I will present some recent research efforts in that direction.

I will not assume familiarity with modal logic, but some mathematical inclination will be useful.