ILLC-LIRa

illc-lira@list.uva.nl

582 discussions

LIRa session (online only): Alexandru Baltag
by LIRa Seminar 10 May '20

10 May '20

Dear all, We will have our next LIRa session on Thursday, May 14th. Our speaker is Alexandru Baltag. You will receive the zoom link and a reminder of the guidelines for online sessions the day before the talk. After the talk, we will continue the discussion with (online) drinks, as usual. You can find the details below. Speaker: Alexandru Baltag Date and Time: Thursday, May 14th 2020, 16:30-18:00, Amsterdam time. Venue: online. Title: From known correlations to the logic of continuous dependence Abstract. An empirical variable is one whose exact value might not be knowable, and instead only inexact approximations can be observed. Examples are in natural sciences, economics etc (where the inexact observations are some form of measurements), but also in the semantics of questions in natural language (where the inexact observations are partial answers). This leads to a topological conception of empirical variables, as maps from the state space into a topological space. Here, the exact value of the variable is represented by the output of the map, while the open neighborhoods of this value represent the knowable approximations of the exact answer. A central tenet in empirical sciences is establishing functional correlations between variables, with a view towards (1) establishing causality, but also (2) predicting the (approximate) value of a hard-to-measure variable Y when given (approximate) value(s) of easier-to-measure variable X. In interrogative terms, this is related to inquisitive implication: every partial answer to question Y is entailed by some partial answer to X. In this talk, I argue that knowability of a dependency amounts to the continuity of the given functional correlation. I give a learning-theoretic justification of this claim, connecting with Kevin Kelly\'s notion of gradual learnability, then I give some concrete examples. Next, I present a complete and decidable axiomatization of the logic of continuous dependence, and briefly skech the ideas behind the proofs. Further, I discuss the distinction between knowing the dependence between X and Y, and knowing how to determine Y (with any desired accuracy) from X: the later is a stronger notion of knowability, that requires the ability to find the accuracy that is needed for X-measurements (to determine Y with the given accuracy). I formalize this distinction in terms of continuity versus uniform continuity of the underlying dependence map, and go on to propose an axiomatization of strongly known dependence, in the framework of uniform spaces (-Andrè Weil\'s qualitative generalization of metric spaces). Time-permitting, I may go back to the problem of learning true causal relations from observed functional correlations. I will end with a number of open questions, some technical and some conceptual. This is ongoing joint work with Johan van Benthem, embodied in a follow-up draft to our joint work on the Logic of Functional Dependence, presented at a previous LIRa seminar. (But my presentation will be self-contained.) Hope to see you there! The LIRa team

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LIRa session (online only): Anthia Solaki
by LIRa Seminar 06 May '20

06 May '20

Dear all, Tomorrow we will have our next LIRa session. Here is the zoom link: https://uva-live.zoom.us/j/92163487348?pwd=cDluVzZxN2hlNVAzZnI1SDdJcU9Bdz09 (Meeting ID: 921 6348 7348, Password: 040025). The details of the talk are below. You can find the guidelines for our online sessions here: https://projects.illc.uva.nl/lgc/seminar/guidelines-for-online-sessions/ Speaker: Anthia Solaki Date and Time: Thursday, May 7th 2020, 16:30-18:00, Amsterdam time. Venue: online Title: A logical formalisation of False Belief Tasks (joint work with Fernando Velázquez-Quesada) Abstract. Theory of Mind, the cognitive capacity to attribute internal mental states to oneself and others, is a crucial component of social skills. Its formal study has become important, witness recent research on reasoning and information update by intelligent agents, and some proposals for its formal modelling have put forward settings based on Epistemic Logic (EL). Still, due to intrinsic idealisations, it is questionable whether EL can be used to model the high-order cognition of \"real\" agents. We propose a mental attribution modelling logical framework based on agents\' temporal visibility, that is more in-line with findings in cognitive science and suitable to model well-known False-Belief tasks. We discuss some of its technical features and argue on why it does justice to empirical observations. We finally extend the temporal visibility models to capture that communication (next to observation) comes into play when attributing beliefs to others. We illustrate the workings of the new system in the modelling of more complicated False-Belief tasks. Hope to see you there! The LIRa team

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LIRa session (online only): Anthia Solaki
by LIRa Seminar 01 May '20

01 May '20

Dear all, We will have our next LIRa session on Thursday, May 7th. Our speaker is Anthia Solaki. You will receive the zoom link and a reminder of the guidelines for online sessions the day before the talk. After the talk, we will continue the discussion with (online) drinks, as usual. Please, find the details below. Speaker: Anthia Solaki Date and Time: Thursday, May 7th 2020, 16:30-18:00, Amsterdam time. Venue: online Title: A logical formalisation of False Belief Tasks (joint work with Fernando Velázquez-Quesada) Abstract. Theory of Mind, the cognitive capacity to attribute internal mental states to oneself and others, is a crucial component of social skills. Its formal study has become important, witness recent research on reasoning and information update by intelligent agents, and some proposals for its formal modelling have put forward settings based on Epistemic Logic (EL). Still, due to intrinsic idealisations, it is questionable whether EL can be used to model the high-order cognition of \"real\" agents. We propose a mental attribution modelling logical framework based on agents\' temporal visibility, that is more in-line with findings in cognitive science and suitable to model well-known False-Belief tasks. We discuss some of its technical features and argue on why it does justice to empirical observations. We finally extend the temporal visibility models to capture that communication (next to observation) comes into play when attributing beliefs to others. We illustrate the workings of the new system in the modelling of more complicated False-Belief tasks. Hope to see you there! The LIRa team

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LIRa session (online only): Carlo Proietti
by LIRa Seminar 29 Apr '20

29 Apr '20

Dear all, Tomorrow we will have our next LIRa session. Here is the zoom link: https://uva-live.zoom.us/j/95748565835?pwd=V1g5RFptUDRDLzNvRGc2Qmp4aURadz09 (Meeting ID: 957 4856 5835, Password: 028909). The details of the talk are below. You can find the guidelines for our online sessions here: https://projects.illc.uva.nl/lgc/seminar/guidelines-for-online-sessions/ Speaker: Carlo Proietti Date and Time: Thursday, April 30th 2020, 16:30-18:00, Amsterdam time. Venue: online Title: DEL for Abstract Argumentation (joint work with Antonio Yuste-Ginel) Abstract. We introduce a multi-agent dynamic epistemic logic for abstract argumentation. The logic brings together tools from dynamic epistemic logic, awareness logic and abstract argumentation. The resulting framework allows reasoning about subtle epistemic and argumentative updates - such as the effects of different levels of trust in a source - and more in general about the epistemic dimensions of strategic and persuasive communication. Our framework consists in the extension of one of the logics proposed by Schwarzentruber et al. in two different directions: (i) enriching its propositional fragment with new propositional variables, in order to capture the notion of fine-grained justification status of an argument, and (ii) adding action models with propositional assignments to the epistemic language, in order to reason about argumentative and epistemic dynamics. Developing (i) and (ii) brings with it some conceptual and technical challenges, such as how to preserve given epistemic model restrictions after action execution. We address these questions and provide complete axiomatisations for different intuitive constraints. Hope to see you there! The LIRa team

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LIRa session (online only): Carlo Proietti
by LIRa Seminar 25 Apr '20

25 Apr '20

Dear all, We will have our next LIRa session on Thursday, April 30th. Our speaker is Carlo Proietti. You will receive the zoom link and a reminder of the guidelines for online sessions the day before the talk. After the talk, we will continue the discussion with (online) drinks, as usual. Please, find the details below. Speaker: Carlo Proietti Date and Time: Thursday, April 30th 2020, 16:30-18:00 Venue: online Title: DEL for Abstract Argumentation (joint work with Antonio Yuste-Ginel) Abstract. We introduce a multi-agent dynamic epistemic logic for abstract argumentation. The logic brings together tools from dynamic epistemic logic, awareness logic and abstract argumentation. The resulting framework allows reasoning about subtle epistemic and argumentative updates – such as the effects of different levels of trust in a source – and more in general about the epistemic dimensions of strategic and persuasive communication. Our framework consists in the extension of one of the logics proposed by Schwarzentruber et al. in two different directions: (i) enriching its propositional fragment with new propositional variables, in order to capture the notion of fine-grained justification status of an argument, and (ii) adding action models with propositional assignments to the epistemic language, in order to reason about argumentative and epistemic dynamics. Developing (i) and (ii) brings with it some conceptual and technical challenges, such as how to preserve given epistemic model restrictions after action execution. We address these questions and provide complete axiomatisations for different intuitive constraints. Hope to see you there! The LIRa team

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LIRa session (online only): Ilaria Canavotto and Eric Pacuit
by LIRa Seminar 22 Apr '20

22 Apr '20

Dear all, Tomorrow we will have our next LIRa session. Here is the zoom link: https://uva-live.zoom.us/j/96573697968?pwd=SlllTXpHL3NIaTJvRW8wZFg4SzM3Zz09 (Meeting ID: 965 7369 7968, Password: 026512). The details of the talk are below. You can find the guidelines for our online sessions here: https://projects.illc.uva.nl/lgc/seminar/guidelines-for-online-sessions/ Speaker: Ilaria Canavotto and Eric Pacuit Date and Time: Thursday, April 23rd 2020, 16:30-18:00 (Amsterdam time) Venue: online Title: Merging STIT and counterfactual logic Abstract. STIT logics and their various extensions have been used to clarify complex moral and legal ideas and to represent game-theoretic situations. Although both of these applications involve counterfactual reasoning, only a few STIT logics explicitly incorporate reasoning about counterfactuals. In this talk, we present a proposal that merges a standard logic of counterfactuals with a STIT logic. Taking a cue from the literature on causal models, we do this by developing and axiomatizing a STIT logic with action types, instants and deviant choices, where a choice is deviant when its performance violates some underlying causal laws, social or legal norms, or other ``rules of the game”. In order to provide a semantics for counterfactuals, we discuss three key intuitions supporting increasingly demanding definitions of similarity between possible histories: the rewind intuition, the causal independence intuition and the no forgetting intuition. In the second half of the talk, we explore an application to the epistemic foundations for backward and forward induction. Hope to see you there! The LIRa team

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Workshop: Quantum and Beyond
by LIRa Seminar 18 Apr '20

18 Apr '20

Dear all, We forward the announcement of the online workshop Quantum and Beyond. Please, find the details below: The meeting \"Quantum and Beyond” on 28 and 29 April 2020, is devoted to recent logical and foundational investigations that have been inspired by quantum theory. After the pioneering approach of Birkhoff and von Neumann in the Thirties, the quantum theoretic formalism has suggested the development of new logical ideas that have been successfully applied to different fields: fuzzy and epistemic logics, quantum information and quantum computation theories, semantics of natural and artistic languages, pattern recognition and machine learning, cognitive sciences. We plan to host 8 lectures starting on 28 April and continuing on 29 April in the morning. Everyone is very welcome to attend via Zoom. More information is available at: https://sites.google.com/site/quantum8beyond/home On behalf of the Organizers, Sonja Smets (University of Amsterdam, ILLC) Roberto Giuntini (University of Cagliari and Centro Linceo Interdisciplinare B. Segre, Rome) Giuseppe Sergioli (University of Cagliari) The LIRa team

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LIRa session (online only): Ilaria Canavotto and Eric Pacuit
by LIRa Seminar 18 Apr '20

18 Apr '20

Dear all, We will have our next LIRa session on Thursday, April 23rd. Our speakers are Ilaria Canavotto and Eric Pacuit. You will receive the zoom link and a reminder of the guidelines for online sessions the day before the talk. After the talk, we will continue the discussion with (online) drinks, as usual. Please, find the details below. Speaker: Ilaria Canavotto and Eric Pacuit Date and Time: Thursday, April 23rd 2020, 16:30-18:00 Venue: online Title: Merging STIT and counterfactual logic Abstract. STIT logics and their various extensions have been used to clarify complex moral and legal ideas and to represent game-theoretic situations. Although both of these applications involve counterfactual reasoning, only a few STIT logics explicitly incorporate reasoning about counterfactuals. In this talk, we present a proposal that merges a standard logic of counterfactuals with a STIT logic. Taking a cue from the literature on causal models, we do this by developing and axiomatizing a STIT logic with action types, instants and deviant choices, where a choice is deviant when its performance violates some underlying causal laws, social or legal norms, or other ``rules of the game”. In order to provide a semantics for counterfactuals, we discuss three key intuitions supporting increasingly demanding definitions of similarity between possible histories: the rewind intuition, the causal independence intuition and the no forgetting intuition. In the second half of the talk, we explore an application to the epistemic foundations for backward and forward induction. Hope to see you there! The LIRa team

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LIRa session (online only): Yu Wei
by LIRa Seminar 15 Apr '20

15 Apr '20

Dear all, Tomorrow we will have our next LIRa session, followed by online drinks as usual. You can find the details of the talk below. Here is the zoom link: https://uva-live.zoom.us/j/99755876133 (Meeting ID: 997 5587 6133). You may find the guidelines of our online sessions here: https://projects.illc.uva.nl/lgc/seminar/guidelines-for-online-sessions/ Speaker: Yu Wei Date and Time: Thursday, April 16th 2020, 16:30-18:00 (Note: the starting time is back to our normal slot of 16:30hrs) Venue: online Title: Quantifier-free Epistemic Term-Modal Logic with Assignments Abstract. In standard epistemic logic, agent names are usually assumed to be common knowledge implicitly, which is unreasonable for various applications. Inspired by term-modal logic and assignment operators in dynamic logic, Yanjing Wang & Jeremy Seligman (2018) introduced a quantifier-free modal predicate logic where names can be non-rigid in order to handle various de dicto /de re distinctions. Their main technical result is a complete axiomatization over constant-domain S5 models. However, it is more interesting to allow varying domains where the existence of all agents is not commonly known, and also to include function symbols as a natural generalization. Note that there are many nontrivial questions about varying-domain models, like the accessibility relations for the agents non-existent at a world, and how to define an epistemic model in this setting. As we will see, with properly defined varying-domain models in place, we can express the meta-level notion “existence” and something just like Barcan formula & Converse Barcan formula in our object language though without any quantifiers. Additionally, varying-domain models provide us with a wider perspective to distinguish two sorts of constant-domain models, and prompt a systematic approach to give axiomatizations over various Kripke and epistemic models. As for the complexity, on one hand, we show the undecidability of all the logics over varying-domain and two kinds of constant-domain epistemic models. On the other hand, we can indeed find some decidable fragments of this modal predicate logic with function symbols. This is joint work with Yanjing Wang and Jeremy Seligman. Reference Wang, Y., Seligman, J. (2018). When names are not commonly known: epistemic logic with assignments. arXiv preprint arXiv:1805.03852. Hope to see you there! The LIRa team

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LIRa session (online only): Yu Wei
by LIRa Seminar 10 Apr '20

10 Apr '20

Dear all, We will have our next LIRa session on Thursday, April 16th, 16:30-18.00. Our speaker is Yu Wei. You will receive the zoom link and a reminder of the guidelines for online sessions the day before the talk. After the talk, we will continue the discussion with (online) drinks, as usual. Please, find the details below. Speaker: Yu Wei Date and Time: Thursday, April 16th 2020, 16:30-18:00 (Note: the starting time is back to our normal slot of 16:30hrs) Venue: online Title: Quantifier-free Epistemic Term-Modal Logic with Assignments Abstract. In standard epistemic logic, agent names are usually assumed to be common knowledge implicitly, which is unreasonable for various applications. Inspired by term-modal logic and assignment operators in dynamic logic, Yanjing Wang & Jeremy Seligman (2018) introduced a quantifier-free modal predicate logic where names can be non-rigid in order to handle various de dicto /de re distinctions. Their main technical result is a complete axiomatization over constant-domain S5 models. However, it is more interesting to allow varying domains where the existence of all agents is not commonly known, and also to include function symbols as a natural generalization. Note that there are many nontrivial questions about varying-domain models, like the accessibility relations for the agents non-existent at a world, and how to define an epistemic model in this setting. As we will see, with properly defined varying-domain models in place, we can express the meta-level notion “existence” and something just like Barcan formula & Converse Barcan formula in our object language though without any quantifiers. Additionally, varying-domain models provide us with a wider perspective to distinguish two sorts of constant-domain models, and prompt a systematic approach to give axiomatizations over various Kripke and epistemic models. As for the complexity, on one hand, we show the undecidability of all the logics over varying-domain and two kinds of constant-domain epistemic models. On the other hand, we can indeed find some decidable fragments of this modal predicate logic with function symbols. This is joint work with Yanjing Wang and Jeremy Seligman. Reference Wang, Y., Seligman, J. (2018). When names are not commonly known: epistemic logic with assignments. arXiv preprint arXiv:1805.03852. Hope to see you there! The LIRa team

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