ILLC-LIRa September 2019

illc-lira@list.uva.nl

1 participants
7 discussions

LIRa Session: Gaia Belardinelli
by LIRa Seminar 27 Sep '19

27 Sep '19

Dear all, We will have our next session on Thursday, October 3rd. Our speaker is Gaia Belardinelli, and you can find the details of the talk below: Speaker: Gaia Belardinelli Date and Time: Thursday, October 3rd 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Gatekeepers in Social Networks: Logics for Communicative Actions. Abstract. Information control has been the subject of investigation in the fields of information theory and social network analysis. Gatekeepers play a central role, as they are the agents that can manipulate the information flow between groups of agents. In this talk, we present a model that captures the essential properties of gatekeepers in a social network. Firstly, we use graph theory to explore the structural dimension of gatekeepers. Secondly, we use notions from Dynamic Epistemic Logic and Coalition Logic to model the dynamics of their informational capabilities. We find that gatekeepers can be categorized into three distinct subclasses, which differ in terms of their structural properties or type of information control. This talk is based on the work I did with Alexandru Baltag for my MSc thesis. Hope to see you there! The LIRa team

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LIRa Session: Raul Fervari
by LIRa Seminar 25 Sep '19

25 Sep '19

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Raul Fervari (Universidad Nacional de Córdoba) Date and Time: Thursday, September 26th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Separation logics: a modal perspective. Abstract. Modal separation logics (MSL) are formalisms that have been recently proposed combining modal operators with separating connectives, both interpreted over one-dimensional Kripke models. In this way, MSL can be seen either as separation logics enriched with local operations to reason about memory states of a piece of software, or either as modal logics with global relation-changing operators (á la sabotage logic). In this talk we will present MSL and some of its most interesting fragments, and discuss some results about complexity, axiom systems and expressivity. We will conclude by discussing some ongoing and future lines of research. Some references: [1] S. Demri and R. Fervari. On the Complexity of Modal Separation Logics. In Proceedings of Advances in Modal Logics AiML’18, pages 179-198. College Publications, 2018. [2] S. Demri, R. Fervari and A. Mansutti. Axiomatising Logics with Separating Conjunction and Modalities. In Proceedings of the 16th European Conference on Logics in Artificial Intelligence (JELIA 2019). Hope to see you there! The LIRa team

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LIRa Session: Raul Fervari
by LIRa Seminar 20 Sep '19

20 Sep '19

Dear all, We will have our next session on Thursday, September 26th. Our speaker is Raul Fervari, and you can find the details of the talk below: Speaker: Raul Fervari (Universidad Nacional de Córdoba) Date and Time: Thursday, September 26th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Separation logics: a modal perspective. Abstract. Modal separation logics (MSL) are formalisms that have been recently proposed combining modal operators with separating connectives, both interpreted over one-dimensional Kripke models. In this way, MSL can be seen either as separation logics enriched with local operations to reason about memory states of a piece of software, or either as modal logics with global relation-changing operators (á la sabotage logic). In this talk we will present MSL and some of its most interesting fragments, and discuss some results about complexity, axiom systems and expressivity. We will conclude by discussing some ongoing and future lines of research. Some references: [1] S. Demri and R. Fervari. On the Complexity of Modal Separation Logics. In Proceedings of Advances in Modal Logics AiML’18, pages 179-198. College Publications, 2018. [2] S. Demri, R. Fervari and A. Mansutti. Axiomatising Logics with Separating Conjunction and Modalities. In Proceedings of the 16th European Conference on Logics in Artificial Intelligence (JELIA 2019). Hope to see you there! The LIRa team

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LIRa Session: Erman Acar
by LIRa Seminar 18 Sep '19

18 Sep '19

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Erman Acar (VU Amsterdam) Date and Time: Thursday, September 19th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: When Satisfiability is easier than Model Checking: A Fragment of Strategy Logic. Abstract. In the design of complex systems, model-checking and satisfiability arise as two prominent decision problems. While model-checking requires the designed system to be provided in advance, satisfiability allows to check if such a system even exists. With very few exceptions, the second problem turns out to be harder than the first one from a complexity-theoretic point of view. In this talk, I will present a recent work which investigates the connection between the two problems for a non-trivial fragment of Strategy Logic (SL) which extends Linear Temporal Logic with first-order quantifications over strategies, thus allowing to explicitly reason about the strategic abilities of agents in a multi-agent system. The SL fragment we consider is obtained by preventing strategic quantifications within the scope of temporal operators. The resulting logic is quite powerful, still allowing to express important game-theoretic properties of multi-agent systems, such as existence of Nash and immune equilibria, as well as to formalise the rational synthesis problem. It turns out that satisfiability for such a fragment is PSPACE-COMPLETE, while its model-checking complexity is 2EXPTIME-HARD. The result is obtained by means of an elegant encoding of the problem into the satisfiability of conjunctive-binding first-order logic, a recently discovered decidable fragment of first-order logic. This is a joint work with Massimo Benerecetti and Fabio Mogavero. Hope to see you there! The LIRa team

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LIRa Session: Erman Acar
by LIRa Seminar 13 Sep '19

13 Sep '19

Dear all, We will have our next session on Thursday, September 19th 2019. Our speaker is Erman Acar and you can find the details of the talk below: Speaker: Erman Acar (VU Amsterdam) Date and Time: Thursday, September 19th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: When Satisfiability is easier than Model Checking: A Fragment of Strategy Logic. Abstract. In the design of complex systems, model-checking and satisfiability arise as two prominent decision problems. While model-checking requires the designed system to be provided in advance, satisfiability allows to check if such a system even exists. With very few exceptions, the second problem turns out to be harder than the first one from a complexity-theoretic point of view. In this talk, I will present a recent work which investigates the connection between the two problems for a non-trivial fragment of Strategy Logic (SL) which extends Linear Temporal Logic with first-order quantifications over strategies, thus allowing to explicitly reason about the strategic abilities of agents in a multi-agent system. The SL fragment we consider is obtained by preventing strategic quantifications within the scope of temporal operators. The resulting logic is quite powerful, still allowing to express important game-theoretic properties of multi-agent systems, such as existence of Nash and immune equilibria, as well as to formalise the rational synthesis problem. It turns out that satisfiability for such a fragment is PSPACE-COMPLETE, while its model-checking complexity is 2EXPTIME-HARD. The result is obtained by means of an elegant encoding of the problem into the satisfiability of conjunctive-binding first-order logic, a recently discovered decidable fragment of first-order logic. This is a joint work with Massimo Benerecetti and Fabio Mogavero. Hope to see you there! The LIRa team

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LIRa session: René Mellema
by LIRa Seminar 11 Sep '19

11 Sep '19

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: René Mellema Date and Time: Thursday, September 12th 2019, 16:30-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: An Inquisitive Dynamic Epistemic Logic with Factual Change. Abstract. In many situations, we want to model the effect of actions on both the knowledge of others, and also what they want to know afterwards. For example, after you hear something fall in another room, you would not only want to know whether others heard that, but also if they want to know what fell down. In this talk we will present a logic for multi-agent modelling for these kinds of situations by combining two logical frameworks, the Logic of Communication and Change and the newer framework of Inquisitive Semantics. The latter is a framework that has been set up to give a reasonable formal interpretation to questions. From this field we will mostly use ideas from Action Model Logic with Issues. This allows us to build a logic where we can model knowledge, including common knowledge; the questions that agents want an answer to, including questions that are shared between agents; and epistemic events like public and private announcements and factual change, all in one logic. This new logic is based on a new inquisitive epistemic logic for relativized group knowledge which we call Inquisitive Epistemic Propositional Dynamic Logic, based on PDL. We will present a sound and complete axiomatisation for this logic and discuss parts of its completeness proof. We enriched this logic with action models that also represent factual change. We call this resulting logic the Logic of Communication, Change, and Issues. We have shown that this logic can be completely reduced to its underlying static language and has a sound and complete axiomatisation. This talk is based on my MSc thesis, which was done under the supervision of Rineke Verbrugge and Floris Roelofsen. Hope to see you there! The LIRa team

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LIRa session: René Mellema
by LIRa Seminar 06 Sep '19

06 Sep '19

Dear all, LIRa is back! We will have our first session on Thursday, September 12th 2019. The regular slot for this term is 16.30-18.00. Our first speaker is René Mellema and you can find the details of the talk below: Speaker: René Mellema Date and Time: Thursday, September 12th 2019, 16:30-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: An Inquisitive Dynamic Epistemic Logic with Factual Change. Abstract. In many situations, we want to model the effect of actions on both the knowledge of others, and also what they want to know afterwards. For example, after you hear something fall in another room, you would not only want to know whether others heard that, but also if they want to know what fell down. In this talk we will present a logic for multi-agent modelling for these kinds of situations by combining two logical frameworks, the Logic of Communication and Change and the newer framework of Inquisitive Semantics. The latter is a framework that has been set up to give a reasonable formal interpretation to questions. From this field we will mostly use ideas from Action Model Logic with Issues. This allows us to build a logic where we can model knowledge, including common knowledge; the questions that agents want an answer to, including questions that are shared between agents; and epistemic events like public and private announcements and factual change, all in one logic. This new logic is based on a new inquisitive epistemic logic for relativized group knowledge which we call Inquisitive Epistemic Propositional Dynamic Logic, based on PDL. We will present a sound and complete axiomatisation for this logic and discuss parts of its completeness proof. We enriched this logic with action models that also represent factual change. We call this resulting logic the Logic of Communication, Change, and Issues. We have shown that this logic can be completely reduced to its underlying static language and has a sound and complete axiomatisation. This talk is based on my MSc thesis, which was done under the supervision of Rineke Verbrugge and Floris Roelofsen. Hope to see you there! The LIRa team

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ILLC-LIRa September 2019