ILLC-LIRa November 2018

illc-lira@list.uva.nl

1 participants
9 discussions

LIRa Session: Krzysztof Apt
by LIRa Seminar 30 Nov '18

30 Nov '18

Dear all, The next LIRa session will take place on Thursday, December 6th. Our speaker is Krzysztof Apt. Please, find the details below: Speaker: Krzysztof Apt Date and Time: Thursday, December 6th 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: The logic of gossiping. Abstract. Gossip protocols are concerned with the spread of knowledge in a social network. They aim at arriving at a situation in which all agents know each other secrets. Recently distributed epistemic gossip protocols were introduced that employ epistemic logic (for instance in statements such as `if I do not know whether agent i knows my secret I communicate it to him\'). To discuss such protocols we developed a simple epistemic logic that allows us to express statements like `agent a knows that agent b is familiar with the secret of agent c.\' An analysis of such statements is surprisingly subtle. We show that the semantics and truth relation of this logic are decidable, which is relevant for the correctness study of the gossip protocols. Also, we discuss an extension allowing one to express common knowledge. Many questions remain open, notably sound and complete axiomatization. Further, there are several types of communication between pairs of agents, each resulting in a different notion of knowledge. The talk is based on joint works with Davide Grossi, Wiebe van der Hoek, and Dominik Wojtczak. Hope to see you there! The LIRa team

1 0

LIRa Session: Johan van Benthem
by LIRa Seminar 28 Nov '18

28 Nov '18

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Johan van Benthem Date and Time: Thursday, November 29th 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Graph Games and Logic Design. Abstract. Graph games are widely used recreationally and for computational purposes. We analyze some main varieties of graph games and show how they suggest design of matching modal logics with interesting properties. Some recent results, many obtained by colleagues and students in China and Stanford, will be presented to show the interest of this particular concrete way of connecting logic and games. But there will also be open problems. (Joint work with Fenrong Liu) References J. van Benthem, 2014, Logic in Games, The MIT Press. J. van Benthem & F. Liu, 2018, Graph Games and Logic Design, Tsinghua University Journal. Hope to see you there! The LIRa team

1 0

LIRa Session: Johan van Benthem
by LIRa Seminar 25 Nov '18

25 Nov '18

Dear all, The next LIRa session will take place on Thursday, November 29th. Our speaker is Johan van Benthem. Please, find the details below: Speaker: Johan van Benthem Date and Time: Thursday, November 29th 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Graph Games and Logic Design . Abstract. Graph games are widely used recreationally and for computational purposes. We analyze some main varieties of graph games and show how they suggest design of matching modal logics with interesting properties. Some recent results, many obtained by colleagues and students in China and Stanford, will be presented to show the interest of this particular concrete way of connecting logic and games. But there will also be open problems. (Joint work with Fenrong Liu) References J. van Benthem, 2014, Logic in Games, The MIT Press. J. van Benthem & F. Liu, 2018, Graph Games and Logic Design, Tsinghua University Journal. Hope to see you there! The LIRa team

1 0

LIRa Session: Alexandra Kuncova
by LIRa Seminar 21 Nov '18

21 Nov '18

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Alexandra Kuncova Date and Time: Thursday, November 22nd 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: On the (In)dispensability of Action Types. Abstract. In my talk, I explore the analysis of ability. Imagine that we place all the cards from a deck face down on a table and ask you to turn over the Queen of Hearts. Are you able to do that? In a certain sense, yes -- we refer to this as causal ability. There are 52 actions of turning over one of the cards available to you and one of them guarantees that you turn over the Queen of Hearts. However, in the epistemic sense, you are not able to turn over the Queen of Hearts, because you do not know which of those 52 actions actually guarantees the result. In my presentation I elaborate on epistemic ability and two ways of modelling it in STIT theory. The standard analysis relies on action types -- as opposed to action tokens -- and states that an agent has the epistemic ability to do something if and only if there is an action type available to her that she knows guarantees it. I will show, however, that these action types are dispensable: I will present a formalism without action types that can simulate the standard analyses of epistemic ability that rely on action types. The beauty of our approach lays in its simplicity: our formalism is a standard epistemic extension of STIT theory, and epistemic ability is characterised by a combination of impersonal possibility, knowledge and agency. No action types, no labels, and no new modalities are needed. In light of this dispensability of action types in an epistemic setting I will finish by reflecting on whether action types might be useful for other senses of agency and ability. (This is based on joint work with Jan Broersen, Hein Duijf, and Aldo Ramirez Abarca.) Hope to see you there! The LIRa team

1 0

LIRa Session: Alexandra Kuncova
by LIRa Seminar 16 Nov '18

16 Nov '18

Dear all, The next LIRa session will take place on Thursday, November 22nd. Our speaker is Alexandra Kuncova. Please, find the details below: Speaker: Alexandra Kuncova Date and Time: Thursday, November 22nd 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: On the (In)dispensability of Action Types. Abstract. In my talk, I explore the analysis of ability. Imagine that we place all the cards from a deck face down on a table and ask you to turn over the Queen of Hearts. Are you able to do that? In a certain sense, yes -- we refer to this as causal ability. There are 52 actions of turning over one of the cards available to you and one of them guarantees that you turn over the Queen of Hearts. However, in the epistemic sense, you are not able to turn over the Queen of Hearts, because you do not know which of those 52 actions actually guarantees the result. In my presentation I elaborate on epistemic ability and two ways of modelling it in STIT theory. The standard analysis relies on action types -- as opposed to action tokens -- and states that an agent has the epistemic ability to do something if and only if there is an action type available to her that she knows guarantees it. I will show, however, that these action types are dispensable: I will present a formalism without action types that can simulate the standard analyses of epistemic ability that rely on action types. The beauty of our approach lays in its simplicity: our formalism is a standard epistemic extension of STIT theory, and epistemic ability is characterised by a combination of impersonal possibility, knowledge and agency. No action types, no labels, and no new modalities are needed. In light of this dispensability of action types in an epistemic setting I will finish by reflecting on whether action types might be useful for other senses of agency and ability. (This is based on joint work with Jan Broersen, Hein Duijf, and Aldo Ramirez Abarca.) Hope to see you there! The LIRa team

1 0

LIRa Session: Johannes Korbmacher
by LIRa Seminar 14 Nov '18

14 Nov '18

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Johannes Korbmacher Date and Time: Thursday, November 15th 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: The Logic of Free Choice Permission. Abstract. Building on a suggestion by Kit Fine, we describe a logic of permission using exact truthmaker semantics. The only logical principle for permission in the system is Free Choice Permission (FCP): P (φ ∨ ψ) ⊨ P φ ∧ P ψ. By drawing on the resources of exact truthmaker semantics, we avoid the standard problems associated with (FCP). Our logic is a positive propositional deontic logic, i.e. it neither has negation nor any kind of implication. The connectives are simply ∨, ∧ and the permission operator P. Notably, the system has no theorems. We give a sound and complete axiomatization in terms of deducibility statements φ ⊢ ψ. We then study extensions of the system with certain plausible principles for permission. In particular, we’ll determine semantic conditions that are equivalent to the validity of Pφ ∧ Pψ ⊨ P(φ ∨ ψ) and of P (φ ∧ ψ) ⊨ P φ ∧ P ψ. (This is a joint work with Albert Anglberger.) Hope to see you there! The LIRa team

1 0

LIRa Session: Johannes Korbmacher
by LIRa Seminar 09 Nov '18

09 Nov '18

Dear all, The next LIRa session will take place on Thursday, November 15th. Our speaker is Johannes Korbmacher. Please, find the details below: Speaker: Johannes Korbmacher Date and Time: Thursday, November 15th 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: The Logic of Free Choice Permission. Abstract. Building on a suggestion by Kit Fine, we describe a logic of permission using exact truthmaker semantics. The only logical principle for permission in the system is Free Choice Permission (FCP): P (φ ∨ ψ) ⊨ P φ ∧ P ψ. By drawing on the resources of exact truthmaker semantics, we avoid the standard problems associated with (FCP). Our logic is a positive propositional deontic logic, i.e. it neither has negation nor any kind of implication. The connectives are simply ∨, ∧ and the permission operator P. Notably, the system has no theorems. We give a sound and complete axiomatization in terms of deducibility statements φ ⊢ ψ. We then study extensions of the system with certain plausible principles for permission. In particular, we’ll determine semantic conditions that are equivalent to the validity of Pφ ∧ Pψ ⊨ P(φ ∨ ψ) and of P (φ ∧ ψ) ⊨ P φ ∧ P ψ. (This is a joint work with Albert Anglberger.) Hope to see you there! The LIRa team

1 0

LIRa Session: Ilaria Canavotto
by LIRa Seminar 07 Nov '18

07 Nov '18

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Ilaria Canavotto Date and Time: Thursday, November 8th 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Introducing Causality in Stit Logic. Abstract. Stit logic is a framework to reason about individual and group agency. More specifically, the central notion that stit theorists aim at modelling is the notion of seeing-to-it-that. Despite some variations, the basic idea is that an agent sees to it that a certain fact, A, is the case just in case her choice ensures that A is the case, no matter what all other agents do. This classic characterization of seeing-to-it-that is typically taken to capture the fact that an agent brings about A. However, the notion of bringing about modelled in stit logic turns out to be considerably narrower than an intuitive notion of bringing about: most of the cases in which we say that an agent brings about a certain fact are cases in which that agent causes that fact and, at the same time, what the other agents do matters. For instance, when we close our office’s door, we are typically prepared to say that we cause the door to be closed (or: we bring about the state that the door is closed), even though the fact that our office mates don’t keep us away from the door matters, since we could not close the door if they did. But, according to stit theory, if this is really the case, then we do not see to it that the door is closed. As we will see, this has important consequences on the possibility of taking standard stit operators as a tool to reason about responsibility. In this talk, I will present a refinement of stit semantics suitable to represent, at least in a weak sense, the causal connections between an agent’s action and its consequences. I will do this step-wise, by including in the semantics, first, action types and, second, a relation of opposition between them. I will show that, in this way, we obtain a framework in which we can interpret new stit operators suitable to model basic degrees of responsibility of an agent. In general, familiarity with stit logic is not necessary for this talk. (This is a joint work with Alexandru Baltag and Sonja Smets.) Hope to see you there! The LIRa team

1 0

LIRa Session: Ilaria Canavotto
by LIRa Seminar 02 Nov '18

02 Nov '18

Dear all, The next LIRa session will take place on Thursday, November 8th. Our speaker is Ilaria Canavotto. Please, find the details below: Speaker: Ilaria Canavotto Date and Time: Thursday, November 8th 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Introducing Causality in Stit Logic. Abstract. Stit logic is a framework to reason about individual and group agency. More specifically, the central notion that stit theorists aim at modelling is the notion of seeing-to-it-that. Despite some variations, the basic idea is that an agent sees to it that a certain fact, A, is the case just in case her choice ensures that A is the case, no matter what all other agents do. This classic characterization of seeing-to-it-that is typically taken to capture the fact that an agent brings about A. However, the notion of bringing about modelled in stit logic turns out to be considerably narrower than an intuitive notion of bringing about: most of the cases in which we say that an agent brings about a certain fact are cases in which that agent causes that fact and, at the same time, what the other agents do matters. For instance, when we close our office’s door, we are typically prepared to say that we cause the door to be closed (or: we bring about the state that the door is closed), even though the fact that our office mates don’t keep us away from the door matters, since we could not close the door if they did. But, according to stit theory, if this is really the case, then we do not see to it that the door is closed. As we will see, this has important consequences on the possibility of taking standard stit operators as a tool to reason about responsibility. In this talk, I will present a refinement of stit semantics suitable to represent, at least in a weak sense, the causal connections between an agent’s action and its consequences. I will do this step-wise, by including in the semantics, first, action types and, second, a relation of opposition between them. I will show that, in this way, we obtain a framework in which we can interpret new stit operators suitable to model basic degrees of responsibility of an agent. In general, familiarity with stit logic is not necessary for this talk. (This is a joint work with Alexandru Baltag and Sonja Smets.) Hope to see you there! The LIRa team

1 0

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

ILLC-LIRa November 2018