ILLC-LIRa October 2018

illc-lira@list.uva.nl

1 participants
8 discussions

LIRa Session: Sanjay Modgil
by LIRa Seminar 31 Oct '18

31 Oct '18

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below and notice our new time slot! Speaker: Sanjay Modgil Date and Time: Thursday, November 1st 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: The Dynamic Turn in Logic: Argument and Dialectic. Abstract. “The lonesome thinker in an armchair is as marginal as he looks: most of our logical skills are displayed in interaction.” - Johan van Benthem. This talk reviews research on argumentative characterisations of non-monotonic logics, emphasizing the extent to which the above quotation serves as a leitmotif for developments within the field. I will first describe how a given theory’s non-monotonic inferences can be decided via the dialectical exchange of arguments and counter-arguments constructed from the given theory. I will then review development of argument game proof theories, and their generalization to formal models of dialogue that enable multiple agents to interactively engage in distributed non-monotonic reasoning. In these dialogues, the inferences are defined with respect to the contents of agents’ locutions that are incrementally submitted during a dialogue, rather than with respect to a given theory. In the second half of the talk, I will review recent collaborative work1 on a novel formulation of dialectical models of inference that address a key limitation of existing models; namely that rationality is guaranteed under the assumption that agents are logically omniscient. Specifically, I will illustrate how our novel formulation formalises real world modes of dialectical reasoning, and in so doing preserves rationality under the assumption that agents are resource bounded. 1Collaborative work with Professor Marcello D’Agostino, Department of Philosophy, University of Milan (M. D\'Agostino and S. Modgil Classical Logic, Argument and Dialectic. In Artificial Intelligence (AIJ), 262, 15 - 51,2018.) . Hope to see you there! The LIRa team

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LIRa Session: Sanjay Modgil (and time-slot change!)
by LIRa Seminar 26 Oct '18

26 Oct '18

Dear all, The next LIRa session will take place on Thursday, November 1st. Our speaker is Sanjay Modgil. NB: Our regular time slot will now be 17:00-18:30. Please, find the details of the talk below: Speaker: Sanjay Modgil Date and Time: Thursday, November 1st 2018, 17:00-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: The Dynamic Turn in Logic: Argument and Dialectic. Abstract. “The lonesome thinker in an armchair is as marginal as he looks: most of our logical skills are displayed in interaction.” - Johan van Benthem. This talk reviews research on argumentative characterisations of non-monotonic logics, emphasizing the extent to which the above quotation serves as a leitmotif for developments within the field. I will first describe how a given theory’s non-monotonic inferences can be decided via the dialectical exchange of arguments and counter-arguments constructed from the given theory. I will then review development of argument game proof theories, and their generalization to formal models of dialogue that enable multiple agents to interactively engage in distributed non-monotonic reasoning. In these dialogues, the inferences are defined with respect to the contents of agents’ locutions that are incrementally submitted during a dialogue, rather than with respect to a given theory. In the second half of the talk, I will review recent collaborative work1 on a novel formulation of dialectical models of inference that address a key limitation of existing models; namely that rationality is guaranteed under the assumption that agents are logically omniscient. Specifically, I will illustrate how our novel formulation formalises real world modes of dialectical reasoning, and in so doing preserves rationality under the assumption that agents are resource bounded. 1Collaborative work with Professor Marcello D’Agostino, Department of Philosophy, University of Milan (M. D\'Agostino and S. Modgil Classical Logic, Argument and Dialectic. In Artificial Intelligence (AIJ), 262, 15 - 51,2018.) . Hope to see you there! The LIRa team

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LIRa Session: Karolina Krzyżanowska
by LIRa Seminar 24 Oct '18

24 Oct '18

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Karolina Krzyżanowska Date and Time: Thursday, October 25th 2018, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: True clauses and false connections: what’s wrong with missing-link conditionals? Abstract. The majority of the prominent theories of indicative conditionals validate the Principle of Conjunctive Sufficiency. That is, on those accounts, whenever the antecedent, P, and the consequent, Q, are true, the conditional, “If P then Q,” is acceptable, whether or not there is a meaningful connection between P and Q. At the same time, almost everyone seems to agree that conditionals without a connection are odd. Gricean explanation of the oddity of missing-link conditionals rests on an observation that such conditionals are rendered highly acceptable only in situations in which a stronger assertion, for instance, that of a conjunction of P and Q, is warranted. Asserting a weaker, less informative conditional is odd because it is a violation of the Maxim of Quantity. In my talk, I will present empirical data that challenge Gricean explanation of why missing-link conditionals are odd. Furthermore, I will argue that these findings can be reconciled with general principles of Gricean pragmatics, but at the cost of giving up Conjunctive Sufficiency. Hope to see you there! The LIRa team

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LIRa Session: Karolina Krzyżanowska
by LIRa Seminar 19 Oct '18

19 Oct '18

Dear all, The next LIRa session will take place on Thursday, October 25th . Our speaker is Karolina Krzyżanowska. Please, find the details below: Date and Time: Thursday, October 25th 2018, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: TBA. Abstract. TBA. Hope to see you there! The LIRa team

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LIRa Session: CANCELLED
by LIRa Seminar 10 Oct '18

10 Oct '18

Dear all, Unfortunately, there will be no LIRa session tomorrow because our speaker is ill. The LIRa team

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LIRa Session: Alexandru Baltag
by LIRa Seminar 10 Oct '18

10 Oct '18

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Alexandru Baltag Date and Time: Thursday, October 11th 2018, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: The Logic of Correlations. Abstract. I present a Logic of Correlations (LC), as an extension of the Epistemic Dependence Logic presented in my 2016 AiML paper, that essentially axiomatized a ``feasible\" version of Vaananen\'s Dependence Logic. The semantics extends van Benthem\'s Generalized-Assignment Semantics of First-Order Logic (on ``dependency models\"). While the usual semantics of FOL allows all possible assignments of variables to objects, a dependency model restricts the range of available assignments to a given subset. One can think of the available assignments as ``possible worlds\", and the FOL quantifiers become Kripke modalities. Dependency models were proposed as a model for capturing dependencies and correlations between variables: essentially, they are the same as the ``teams\" (sets of assignments) used in Hodges\' team semantics for Dependence Logic. This modal version of FOL is known to be decidable, but unfortunately it is so weak that it cannot actually express variable dependencies in an explicit manner (though the model still implicitly captures these dependencies). My Epistemic Dependence Logic proposed a remedy to this limitation, by adding an epistemic operator K_y x (x is knowable given y), that captures a \'local\' version of the so-called dependence atoms from Dependence Logic: all assignments (available in the model) that agree with the current assignment on y also agree with it on x. In this talk I generalize this further, by introducing accessibility relations R for informational ``links\" between assignments. A link is a finite relation between variables. Two assignments w and v are linked by the corresponding accessibility relation if for every pair (x,y) in the link we have w(x)=v(y). In other words, links capture commonality of objects between assignments: x denotes the same object in world w as the one denoted by y in world v. Correlations are dependencies between links, that express informational dependencies between them. LC can be of use in Computer Science to reason about functional dependencies in a database, but also in Physics to encode natural laws capturing causal correlations between physical variables, etc..Unlike Dependence Logic, LC is decidable. Time-permitting, I will try to sketch the main ideas behind the decidability proof (based on an elaboration of the quasi-model method pioneered by van Benthem, and closely related to the mosaic method of Andreka and Nemeti). . Hope to see you there! The LIRa team

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LIRa Session: Alexandru Baltag
by LIRa Seminar 05 Oct '18

05 Oct '18

Dear all, The next LIRa session will take place on Thursday, October 11th. Our speaker is Alexandru Baltag. Please, find the details below: Speaker: Alexandru Baltag Date and Time: Thursday, October 11th 2018, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: The Logic of Correlations Abstract: I present a Logic of Correlations (LC), as an extension of the Epistemic Dependence Logic presented in my 2016 AiML paper, that essentially axiomatized a \"feasible\" version of Vaananen\'s Dependence Logic. The semantics extends van Benthem\'s Generalized-Assignment Semantics of First-Order Logic (on \"dependency models\"). While the usual semantics of FOL allows all possible assignments of variables to objects, a dependency model restricts the range of available assignments to a given subset. One can think of the available assignments as ``possible worlds\", and the FOL quantifiers become Kripke modalities. Dependency models were proposed as a model for capturing dependencies and correlations between variables: essentially, they are the same as the \"teams\" (sets of assignments) used in Hodges\' team semantics for Dependence Logic. This modal version of FOL is known to be decidable, but unfortunately it is so weak that it cannot actually express variable dependencies in an explicit manner (though the model still implicitly captures these dependencies). My Epistemic Dependence Logic proposed a remedy to this limitation, by adding an epistemic operator K_y x (x is knowable given y), that captures a `local\' version of the so-called dependence atoms from Dependence Logic: all assignments (available in the model) that agree with the current assignment on y also agree with it on x. In this talk I generalize this further, by introducing accessibility relations R for informational \"links\" between assignments. A link is a finite relation between variables. Two assignments w and v are linked by the corresponding accessibility relation if for every pair (x,y) in the link we have w(x)=v(y). In other words, links capture commonality of objects between assignments: x denotes the same object in world w as the one denoted by y in world v. Correlations are dependencies between links, that express informational dependencies between them. LC can be of use in Computer Science to reason about functional dependencies in a database, but also in Physics to encode natural laws capturing causal correlations between physical variables, etc..Unlike Dependence Logic, LC is decidable. Time-permitting, I will try to sketch the main ideas behind the decidability proof (based on an elaboration of the quasi-model method pioneered by van Benthem, and closely related to the mosaic method of Andreka and Nemeti). Hope to see you there! The LIRa team

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DIP Colloquium this week
by LIRa Seminar 01 Oct '18

01 Oct '18

Dear all, As you might have noticed, there is no LIRa session this Thursday. Instead, we encourage you to attend the DIP Colloquium talk by Peter Gärdenfors. You can find the details below: Speaker: Peter Gärdenfors (Lund) Title: Where Do Semantic Domains Come From Date: Thursday 4 October 2018 Time: 11:00 - 12:30 Location: ILLC seminar room F1.15 Hope to see you there! The LIRa team

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ILLC-LIRa October 2018