ILLC-LIRa March 2019

illc-lira@list.uva.nl

1 participants
9 discussions

LIRa Session: Malvin Gattinger
by LIRa Seminar 29 Mar '19

29 Mar '19

Dear all, The next LIRa session will take place on Thursday, April 4th. Please, find the details below: Speaker: Malvin Gattinger (University of Groningen) Date and Time: Thursday, April 4th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Adding Boolean Definitions to Public Announcement Logic. Abstract. In standard epistemic logic, knowing p means to know that p is true, not saying anything about understanding p. In this talk I will present joint work with Yanjing Wang where we extend PAL to address this limitation. We define the meaning of propositions with boolean formulas and add an operator for `equivalence by definition\' to the language. We can then model agents with different knowledge or belief about both the truth value and the meaning of propositions. For example, an agent may understand a proposition without knowing its truth value or the other way round. Moreover, multiple agents might agree that something is true without agreeing on its meaning and vice versa. The talk will include various examples and a sketch of the completeness proof. It should be accessible to everyone with some background in epistemic logic. Hope to see you there! The LIRa team

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LIRa Session: Peter Hawke
by LIRa Seminar 27 Mar '19

27 Mar '19

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Peter Hawke (ILLC) Date and Time: Thursday, March 28th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Logical Omniscience and Knowledge Per se. Abstract. I\'ll report on the latest developments in an ongoing project on the problem of logical omniscience, emphasizing recent technical developments (joint work with Aybuke Ozgun and Franz Berto). A problem of logical omniscience arises, roughly, when, relative to a class of agents, (i) one\'s theory of an epistemic attitude is committed to it being closed under logical implication, and (ii) this is, prima facie, a misrepresentation of that attitude. We concentrate on a fundamental version of the problem, concerning ordinary knowledge ascription (\'knowledge per se\') and arbitrary agents. Though logical omniscience is obviously problematic for a theory of knowledge per se, it is plausible that knowledge per se obeys some (static and dynamic) logical principles. We try to capture this with three complementary tools: (i) taking content as composed of truth conditions and topic; (ii) taking minds as fragmented; (iii) taking knowledge as defeasible. We compare our logical system to related ones and exhibit soundness and completeness results. Hope to see you there! The LIRa team

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LIRa Session: Fausto Barbero
by LIRa Seminar 19 Mar '19

19 Mar '19

Dear all, The next LIRa session will take place this Thursday. Our speaker is Fausto Barbero (and not Thomas Schindler, as was announced in the ILLC newsletter!). You can find more details on the talk below: Speaker: Fausto Barbero (University of Helsinki) Date and Time: Thursday, March 21st 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Interventionist Counterfactuals in Team Semantics. Abstract. Team semantics is a generalization of Tarskian semantics which allows the introduction of a greater variety of logical operators - most notably, atoms which express dependencies among variables. This extra degree of freedom is obtained by replacing the notion of satisfaction by an assignment with satisfaction by a set of assignments (\"team\"). I will show how to enrich this framework so that a notion of intervention (in the spirit of structural equation modeling) can be applied to teams. After this move, it becomes possible to introduce interventionist counterfactuals over teams, and express a variety of notions of causal dependence in terms of them. I will consider a basic formalism which conservatively extends the usual languages of causal modelling, and some further operators. Passing from teams to multiteams (multisets of assignments), we will see a way of introducing probabilities in the framework. It will emerge that some distinctions made in causal modelling, e.g. between \"do expressions\" and \"counterfactual expressions\", can be explained in terms of commutation of simpler logical operators. . Hope to see you there! The LIRa team

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LIRa Session: Fausto Barbero
by LIRa Seminar 15 Mar '19

15 Mar '19

Dear all, The next LIRa session will take place on Thursday, March 21st. Please, find the details below: Speaker: Fausto Barbero (University of Helsinki) Date and Time: Thursday, March 21st 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Interventionist Counterfactuals in Team Semantics. Abstract. Team semantics is a generalization of Tarskian semantics which allows the introduction of a greater variety of logical operators - most notably, atoms which express dependencies among variables. This extra degree of freedom is obtained by replacing the notion of satisfaction by an assignment with satisfaction by a set of assignments (\"team\"). I will show how to enrich this framework so that a notion of intervention (in the spirit of structural equation modeling) can be applied to teams. After this move, it becomes possible to introduce interventionist counterfactuals over teams, and express a variety of notions of causal dependence in terms of them. I will consider a basic formalism which conservatively extends the usual languages of causal modelling, and some further operators. Passing from teams to multiteams (multisets of assignments), we will see a way of introducing probabilities in the framework. It will emerge that some distinctions made in causal modelling, e.g. between \"do expressions\" and \"counterfactual expressions\", can be explained in terms of commutation of simpler logical operators. . Hope to see you there! The LIRa team

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LIRa Session: Bahareh Afshari
by LIRa Seminar 13 Mar '19

13 Mar '19

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Bahareh Afshari (ILLC) Date and Time: Thursday, March 14th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: An infinitary treatment of fixed point modal logic. Abstract. Fixed point modal logic deals with the concepts of induction and recursion in a most fundamental way. The term refers to any logic built on the foundation of modal logic that features inductively and/or co-inductively defined operators. Examples range from simple temporal logics (e.g. Tense Logic and Linear Time Logic) to the highly expressive Modal Mu-Calculus and its extensions. In this talk I will introduce the modal mu-calculus and present a complete proof system for it based on nested sequents. We will see how the proof system can be used to obtain a proof of the finite model property and, time permitting, I will also explain how the framework lends itself to a sound and complete axiomatisation for the extension of mu-calculus with backward modalities. (Joint work with Gerhard Jäger and Graham Leigh) Hope to see you there! The LIRa team

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LIRa Session: Bahareh Afshari
by LIRa Seminar 08 Mar '19

08 Mar '19

Dear all, The next LIRa session will take place on Thursday, March 14th. Please, find the details below: Speaker: Bahareh Afshari (ILLC) Date and Time: Thursday, March 14th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: An infinitary treatment of fixed point modal logic. Abstract. Fixed point modal logic deals with the concepts of induction and recursion in a most fundamental way. The term refers to any logic built on the foundation of modal logic that features inductively and/or co-inductively defined operators. Examples range from simple temporal logics (e.g. Tense Logic and Linear Time Logic) to the highly expressive Modal Mu-Calculus and its extensions. In this talk I will introduce the modal mu-calculus and present a complete proof system for it based on nested sequents. We will see how the proof system can be used to obtain a proof of the finite model property and, time permitting, I will also explain how the framework lends itself to a sound and complete axiomatisation for the extension of mu-calculus with backward modalities. (Joint work with Gerhard Jäger and Graham Leigh) Hope to see you there! The LIRa team

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LIRa Session: Shane Steinert-Threlkeld
by LIRa Seminar 06 Mar '19

06 Mar '19

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Shane Steinert-Threlkeld (ILLC) Date and Time: Thursday, March 7th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Explaining Semantic Universals. Abstract. Semantic universals are properties of meaning that are attested in all of the languages of the world. In this talk, I develop an explanation for why such universals arise: expressions satisfying them are easier to learn than those that do not. Using techniques from machine learning, I show that this answer can provide a unified explanation of universals in three disparate linguistic domains, encompassing both function and content words: quantifiers, responsive predicates, and color terms. I conclude by canvassing ongoing work on this project. Hope to see you there! The LIRa team

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LIRa-related events
by LIRa Seminar 04 Mar '19

04 Mar '19

Dear all, We would like to bring the following two events to your attention, as they are closely related to our LIRa topics. You are also encouraged to submit your work! 1) IACAP 2019: Distributed Computing and Epistemic Logic Track (June 5, UNAM, Mexico City. Deadline for submissions: March 24, 2019) You can find more about IACAP in the following link: https://projects.illc.uva.nl/lgc/seminar/2019/03/special-extended-cfa-iacap… 2) 2nd DaLi. Dynamic Logic: New Trends and Applications (October 9, 2019, Porto, Portugal. Deadline for submissions: June 14, 2019) You can find more about DaLi in the following link: https://projects.illc.uva.nl/lgc/seminar/2019/03/cfp-2nd-dali-dynamic-logic… The LIRa team

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LIRa Session: Shane Steinert-Threlkeld
by LIRa Seminar 03 Mar '19

03 Mar '19

Dear all, The next LIRa session will take place on Thursday, March 7th. Please, find the details below: Speaker: Shane Steinert-Threlkeld (ILLC) Date and Time: Thursday, March 7th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Explaining Semantic Universals. Abstract. Semantic universals are properties of meaning that are attested in all of the languages of the world. In this talk, I develop an explanation for why such universals arise: expressions satisfying them are easier to learn than those that do not. Using techniques from machine learning, I show that this answer can provide a unified explanation of universals in three disparate linguistic domains, encompassing both function and content words: quantifiers, responsive predicates, and color terms. I conclude by canvassing ongoing work on this project. Hope to see you there! The LIRa team

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ILLC-LIRa March 2019