The first edition of this workshop has been held on 3 May 2011 at Brussels, Belgium. In its second edition, Dynamics in Logic will keep its goal of bringing together a small group of people who are currently very active on the area of dynamic logic and related fields to exchange ideas, get to know each other's work and research group better.

## Program

10.00 – 10.30 | Coffee |

10.30 – 11.15 | Guillaume Aucher (University Rennes 1/INRIA) |

DEL-sequents for Progression, Regression and Epistemic Planning | |

11.15 – 12.00 | Tomas Bolander (Technical University of Denmark) |

Epistemic and Doxastic Planning for Single- and Multi-Agent Systems |

12.00 – 14.00 | Lunch break |

14.00 – 14.45 | Thomas Ågotnes (University of Bergen) |

Playing Games with Dynamic Epistemic Logic | |

14.45 – 15.30 | Andreas Herzig (University of Toulouse) |

Uniform Strategies in the Dynamic Epistemic Logic of Propositional Control |

15.30 – 16.15 | Coffee break |

16.15 – 17.00 | Wojtek Jamroga (University of Luxembourg) |

Comparing Variants of Strategic Ability |

17.00 – 17.30 | Discussion, final considerations, announcements, ... |

## Venue

The workshop will be held at the following address:

room F.042

Maison de la Recherche

Université Lille 3 Charles-de-Gaulle

3 Rue Barreau

59653 Villeneuve-d'Ascq

France

View Larger Map

The campus of the University of Lille 3 is easily accessible from the city center of Lille via the subway:

- Take subway line 1, direction "4 Cantons".
- Exit at station "Pont de Bois".
- Take to the left at the "Rue Baudouin IX" and then to the right at the "Avenue du Pont de Bois". Pedestrian access to the campus is through the bridge which crosses the avenue du Pont de Bois.

For more information, please follow the following links.

- Map of the campus. (The "Maison de la Recherche" is in green, on the building F located at the top left corner.)
- Subway Map.
- Les itinéraires (only in French, sorry!)

## Admission

Admission is free, but we have a very limited number of places available. If you are interested in attending the workshop, please send an email to delima@cril.fr.

## Organization Committee

- Tiago de Lima (University Lille Nord de France – UArtois and CNRS)
- Sébastien Magnier (University of Lille)

## Co-Organized Event

Dynamics in Logic is co-organized with the workshop Dialogue, Argumentation and Knowledge to be held at the same venue on the March 2nd.

## Abstracts and Presentations

###
10.30 – 11.15

Guillaume Aucher (University Rennes 1/INRIA)

DEL-sequents for Progression, Regression and Epistemic Planning

Dynamic Epistemic Logic (DEL) deals with the representation and the study in a multi-agent setting of knowledge and belief change. It can express in a uniform way epistemic statements about:

- what is true about an initial situation
- what is true about an event occurring in this situation
- what is true about the resulting situation after the event has occurred.

We axiomatize within the DEL framework what we can infer about (3) given (1) and (2), what we can infer about (2) given (1) and (3), and what we can infer about (1) given (2) and (3). These three inference problems are related to classical problems addressed under different guises in artificial intelligence and theoretical computer science, which we call respectively progression, epistemic planning and regression. Given three formulas φ, φ' and φ'' describing respectively (1), (2) and (3), we also show how to build three formulas φ⊗φ', φ\φ'' and φ'/φ'' which capture respectively all the information which can be inferred about (3) from φ and φ', all the information which can be inferred about (2) from φ and φ'', and all the information which can be inferred about (1) from φ' and φ''. We show how our results extend to other modal logics than K. In our proofs and definitions, we resort to a large extent to the normal form formulas for modal logic originally introduced by Kit Fine.

###
11.15 – 12.00

Thomas Bolander (Technical University of Denmark)

Epistemic and Doxastic Planning for Single- and Multi-Agent Systems

This is joint work with Mikkel Birkegaard Andersen and Martin Holm Jensen.

I will present a framework for automated planning based on dynamic epistemic logic (DEL).
DEL-based planning generalises classical planning in several significant ways, most notably by giving the planning agent the ability to reason about the knowledge, beliefs and actions of other agents as part of its planning process.
This ability is essential to achieve efficient and intelligent communication and collaboration in multi-agent settings.
I will first present the purely epistemic planning framework, in which the states of planning problems are multi-pointed epistemic models and the actions are multi-pointed event models (with postconditions).
It is shown that in this framework, plan existence in the single-agent case is decidable, but undecidable in general in the multi-agent case.
Second, I will sketch our work in progress on generalising the framework from epistemic models to plausibility models.
Using plausibility models allows the planning agent to reason about the most plausible outcomes of its possible actions, and thus to prune the search space significantly by only considering these outcomes, and rely on replanning if the expected outcomes are not the ones being realised at run-time.

###
14.00 – 14.45

Thomas Ågotnes (University of Bergen)

Playing Games with Dynamic Epistemic Logic

Dynamic epistemic logic describes the possible information-changing actions available to individual agents, and their knowledge pre- and post conditions.
For example, public announcement logic describes actions in the form of public, truthful announcements.
However, little research so far has considered describing and analysing rational choice between such actions, i.e., predicting what rational self-interested agents actually will or should do.
Since the outcome of information exchange ultimately depends on the actions chosen by all the agents in the system, and assuming that agents have preferences over such outcomes, this is a game theoretic scenario.
This is an interesting general research direction, combining logic and game theory in the study of rational information exchange.
In the talk I will, in particular, focus on two particular cases.
First, I consider the case where available actions are public announcements, and where each agent has a (typically epistemic) goal formula that she would like to become true.
What will each agent announce?
The truth of the goal formula also depends on the announcements made by other agents, thus we have a game-theoretic scenario.
I discuss how such **public announcement games** can be analysed.
Second, I consider the similar setting where instead of choosing an announcement each player chooses a question the other player is obliged to truthfully answer.
What are the best questions to ask?
Again, this question can be discussed by analysing the resulting **question-answer games**.
The talk is based on joint work with Johan van Benthem, Hans van Ditmarsch and Stefan Minica.

###
14.45 – 15.30

Andreas Herzig (University of Toulouse)

Uniform Strategies in the Dynamic Epistemic Logic of Propositional Control

We study uniform strategies in the framework of models of propositional control. In that logic each agent has a repertoire of actions each of which consists in setting a propositional variable to true or false. This provides compact representations of both alternating-time transition systems (providing semantics for CL and ATL) and BR+AC structures (providing semantics for STIT logics). The models allow to interpret a language with modal operators of agency and knowledge, yielding a simple dynamic epistemic logic of propositional control DEL-PC. We prove that the logic is decidable.

###
16.15 – 17.00

Wojtek Jamroga (University of Luxembourg)

Comparing Variants of Strategic Ability

Alternating-time temporal logic (ATL) is a modal logic that allows to reason about agents' abilities in game-like scenarios. Semantic variants of ATL are usually built upon different assumptions about the kind of game that is played, including capabilities of agents (perfect vs. imperfect information, perfect vs. imperfect memory, etc.). We show that different semantics of ability give rise to different classes of games, and study their relationship.