ILLC-LIRa

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LIRa Session: Sonja Smets (Thursday 16 September at 16:30)
by LIRa Seminar 10 Sep '21

10 Sep '21

Dear all, We will have our next LIRa session next week. Please use our recurring zoom link: https://uva-live.zoom.us/j/88142993494?pwd=d1BsQWR4T2UyK0Job29YNThjaGRkUT09 (Meeting ID: 881 4299 3494, Passcode: 352984) You can find the details of the talk below. Speaker: Sonja Smets Date and Time: Thursday, September 16th 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Learning what Others Know Abstract. I will present recent work on modelling scenarios in which agents read or communicate (or somehow gain access to) all the information stored at specific sources, or possessed by some other agents (including information of a non-propositional nature, such as data, passwords etc). Modelling such scenarios requires us to extend the framework of epistemic logics to one in which we abstract away from the specific announcement and formalize directly the action of sharing ‘all you know’ (with some or all of the other agents). In order to do this, we introduce a general framework for such informational events, that subsumes actions such as “sharing all you know” with a group or individual, giving one access to some folder or database, hacking a database without the owner\'s knowledge, etc. We formalize their effect, i.e. the state of affairs in which one agent (or group of agents) has ‘epistemic superiority’ over another agent (or group). Concretely, we express epistemic superiority using comparative epistemic assertions between individuals and groups (as such extending the comparison-types considered in [5]). Another ingredient is a new modal operator for \'common distributed knowledge\', that combines features of both common knowledge and distributed knowledge, and characterizes situations in which common knowledge can be gained in a larger group of agents (formed of a number of subgroups) by communication only within each of the subgroups. We position this work in the context of other known work such as: the problem of converting distributed knowledge into common knowledge via acts of sharing [4]; the more semantic approach in [2] on communication protocols requiring agents to ‘tell everybody all they know’; the work on public sharing events with a version of common distributed knowledge in [3]; and the work on resolution actions in [6]. This presentation is based on joint work with Alexandru Baltag in [1], and it subsumes and extends the material presented by Alexandru in his LIRa presentation in February 2020. [1] A. Baltag and S. Smets, Learning what others know, in L. Kovacs and E. Albert (eds.), LPAR23 proceedings of the International Conference on Logic for Programming, AI and Reasoning, EPiC Series in Computing, 73:90-110, 2020. https://doi.org/10.29007/plm4 [2] A. Baltag and S. Smets, Protocols for Belief Merge: Reaching Agreement via Communication, Logic Journal of the IGPL, 21(3):468-487, 2013. https://doi.org/10.1093/jigpal/jzs049 [3] A. Baltag, What is DEL good for? Lecture at the ESSLLI2010-Workshop on Logic, Rationality and Intelligent Interaction, 16 August 2010. [4] J. van Benthem, One is a lonely number. In P. Koepke Z. Chatzidakis and W. Pohlers, (eds.) Logic Colloquium 2002, 96-129, ASL and A.K. Peters, Wellesley MA, 2002. [5] H. van Ditmarsch, W. van der Hoek & B. Kooi, Knowing More - from Global to Local Correspondence, Proc. of IJCAI-09, 955--960, 2009. [6] T. Agotnes and Y.N. Wang, Resolving Distributed Knowledge, Artificial Intelligence, 252: 1--21, 2017. https://doi.org/10.1016/j.artint.2017.07.002 Hope to see you there! The LIRa team

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Welcome back! First LIRa Session after the summer break: Sonja Smets on 16 Sepember
by LIRa Seminar 02 Sep '21

02 Sep '21

Dear all, We will start again with the LIRa seminar in two weeks from today. Our first talk of the semester will be given by Sonja Smets on 16 September at 16:30, online via Zoom. You can find the details of the talk below. Speaker: Sonja Smets Date and Time: Thursday, September 16th 2021, 16:30-18:00, Amsterdam time. Venue: online. A link to join the session will be included in the next reminder e-mail. Title: Learning what Others Know Abstract. I will present recent work on modelling scenarios in which agents read or communicate (or somehow gain access to) all the information stored at specific sources, or possessed by some other agents (including information of a non-propositional nature, such as data, passwords etc). Modelling such scenarios requires us to extend the framework of epistemic logics to one in which we abstract away from the specific announcement and formalize directly the action of sharing ‘all you know’ (with some or all of the other agents). In order to do this, we introduce a general framework for such informational events, that subsumes actions such as “sharing all you know” with a group or individual, giving one access to some folder or database, hacking a database without the owner\'s knowledge, etc. We formalize their effect, i.e. the state of affairs in which one agent (or group of agents) has ‘epistemic superiority’ over another agent (or group). Concretely, we express epistemic superiority using comparative epistemic assertions between individuals and groups (as such extending the comparison-types considered in [5]). Another ingredient is a new modal operator for \'common distributed knowledge\', that combines features of both common knowledge and distributed knowledge, and characterizes situations in which common knowledge can be gained in a larger group of agents (formed of a number of subgroups) by communication only within each of the subgroups. We position this work in the context of other known work such as: the problem of converting distributed knowledge into common knowledge via acts of sharing [4]; the more semantic approach in [2] on communication protocols requiring agents to ‘tell everybody all they know’; the work on public sharing events with a version of common distributed knowledge in [3]; and the work on resolution actions in [6]. This presentation is based on joint work with Alexandru Baltag in [1], and it subsumes and extends the material presented by Alexandru in his LIRa presentation in February 2020. [1] A. Baltag and S. Smets, Learning what others know, in L. Kovacs and E. Albert (eds.), LPAR23 proceedings of the International Conference on Logic for Programming, AI and Reasoning, EPiC Series in Computing, 73:90-110, 2020. https://doi.org/10.29007/plm4 [2] A. Baltag and S. Smets, Protocols for Belief Merge: Reaching Agreement via Communication, Logic Journal of the IGPL, 21(3):468-487, 2013. https://doi.org/10.1093/jigpal/jzs049 [3] A. Baltag, What is DEL good for? Lecture at the ESSLLI2010-Workshop on Logic, Rationality and Intelligent Interaction, 16 August 2010. [4] J. van Benthem, One is a lonely number. In P. Koepke Z. Chatzidakis and W. Pohlers, (eds.) Logic Colloquium 2002, 96-129, ASL and A.K. Peters, Wellesley MA, 2002. [5] H. van Ditmarsch, W. van der Hoek & B. Kooi, Knowing More - from Global to Local Correspondence, Proc. of IJCAI-09, 955--960, 2009. [6] T. Agotnes and Y.N. Wang, Resolving Distributed Knowledge, Artificial Intelligence, 252: 1--21, 2017. https://doi.org/10.1016/j.artint.2017.07.002 Hope to see you there! The LIRa team

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LIRa-related CfP: Special Issue of APAL on \"Combining Probability and Logic\"
by LIRa Seminar 06 Aug '21

06 Aug '21

Dear all, The following Call for Papers might be of interest to the LIRa audience: We invite submissions for a Special Issue on “Combining Probability and Logic”, to be published with Annals of Pure and Applied Logic. Classically, logic and probability offer competing representations of partial or incomplete information, with the former assuming a qualitative perspective on uncertainty and the latter focusing on a quantitative account. Both provide their own policies for updating on new information, combining evidence from different sources, and acting under partial information. We solicit submissions of original papers that bridge these two perspectives. These could, for instance, connect representations of inductive reasoning in either setting, but they may also apply to specific sub-areas, such as game theory, network theory, causal modelling, machine learning, or maximum entropy reasoning. Likewise, the Special Issue is interested in articles that apply probabilistic tools to the study of logical systems or that use logical frameworks, classical or substructural, for understanding probabilistic approaches. The Special Issue is related to the topics of the conference Progic 2021: The Tenth Workshop on Combining Probability and Logic (https://www.fatil.philosophie.uni-muenchen.de/events/defence_inductive_logi…). Workshop participants, as well as other authors are invited to submit contributions. In line with the policy of Annals of Pure and Applied Logic, submissions are expected to be of high quality and contain relevant new logical results that are of significant interest to a substantial number of logicians. To assess fit with the journal’s scope, authors are required to submit a suitable abstract prior to submission of the full manuscript. The Guest Editors will then, within three weeks, reach an assessment as to whether the contribution fits the journal’s scope or how such fit can be ensured. In case of doubt whether a prospective submission fits the intended scope, we invite authors to contact the Guest Editors well in advance of the deadline. All submissions will be refereed according to the standards of Annals of Pure and Applied Logic. Please ensure that you read the Guide for Authors before writing your manuscript (https://www.elsevier.com/journals/annals-of-pure-and-applied-logic/0168-007…). Submissions can me made through https://www.editorialmanager.com/apal/default.aspx. When submitting your contribution, please select VSI: PROGIC21 SI. The deadline for submitting abstracts is September 30, 2021. The deadline for submitting full manuscripts is December 31, 2021. For more information, please contact the Guest Editors: Dominik Klein (Utrecht University) d.klein at uu.nl Soroush Rafiee Rad (University of Amsterdam) s.rafieerad at uva.nl Thomas Scanlon (University of California, Berkeley) scanlon at math.berkeley.edu Francesca Zaffora Blando (Carnegie Mellon University) fzaffora at andrew.cmu.edu The LIRa team

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CANCELLED: DIEP seminar by Alexandru Baltag
by LIRa Seminar 16 Jun '21

16 Jun '21

Dear all, Unfortunately the DIEP seminar by Alexndru Baltag that was scheduled for tomorrow (June 17th 11.00 am) is cancelled due to the heat wave. The talk will be rescheduled for September and will get back to you with the details in due time. Please note that it is *only* the DIEP seminar in the morning that is canceled and the weekly LIRa talk scheduled for tomorrow 15.00 (please note the unusual time!), will be held as planned. All the best, The LIRa team

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Tomorrow: DIEP talk (Alexandru Baltag) and LIRa Session *AT UNUSUAL TIME* (Cedegao Zhang)
by LIRa Seminar 16 Jun '21

16 Jun '21

Dear all, Tomorrow we will have two events of interest to the LIRa audience. The first is the DIEP talk of Alexandru Baltag, from 11:00 to 12:30. The second is our LIRa session with Cedegao Zhang, from 15:00 to 16:30 (please note the ***UNUSUAL TIME*** compared to our regular sessions!). You can find the details for both events, as well as their Zoom links, below. ----------------------------------------------------- *DIEP talk* Date and time: Thursday, June 17th 2021, 11:00-12:30, Amsterdam time. Speaker: Alexandru Baltag (UvA) Title: Group (Ir)Rationality: Can Logic help? Abstract: I present some applications of logical methods (in particular, of so-called dynamic epistemic logics) to the study of emergent phenomena in groups of `agents\\\', capable of reflection, communication, reasoning, argumentation etc.The main focus on the understanding of belief/preference formation and diffusion in social networks, and on how this affects the group\\\'s ``epistemic potential\\\": the ability of the agents to track the truth of the matter (with respect to some given relevant topic). While in some cases, ``wisdom of the crowds\\\" can increase the epistemic potential, in other situations the group\\\'s dynamics leads to informational distortions (-- the ``madness of the crowds\\\": cascades, ``groupthink\\\", the curse of the committee, pluralistic ignorance, group polarization, doxastic cycles etc). I explain how logic (in combination with probabilistic methods) can be used to provide some explanations for both types of situations, as well as to suggest some partial solutions to informational distortions. Zoom link: https://uva-live.zoom.us/j/85608909905 ---------------------------------------------------- *LIRa Session* Speaker: Cedegao Zhang (University of California, Berkeley) Date and Time: Thursday, June 17th 2021, 15:00-16:30, Amsterdam time. Title: A Computational Model of Higher-Order Epistemic Reasoning. Abstract. Reasoning about what other people know is an important cognitive ability, known as epistemic reasoning, which has fascinated psychologists, economists, and logicians. We propose a computational model of humans’ epistemic reasoning, including higher-order epistemic reasoning—reasoning about what one person knows about another person’s knowledge—that we test in an experiment using a deductive card game called “Aces and Eights”. Our starting point is the model of perfect higher-order epistemic reasoners given by the framework of dynamic epistemic logic. We modify this idealized model with bounds on the level of feasible epistemic reasoning and stochastic update of a player’s space of possibilities in response to new information. These modifications are crucial for explaining the variation in human performance across different participants and different games in the experiment. Our results demonstrate how research on epistemic logic and cognitive models can inform each other. This is a joint work with Ham Huang and Wesley Holliday. A preprint is available at https://psyarxiv.com/7hkzd/. Zoom link: https://uva-live.zoom.us/j/92907704256?pwd=anY3WkFmQVhLZGhjT2JXMlhjQVl1dz09 (Meeting ID: 929 0770 4256, Passcode: 036024) Hope to see you there! The LIRa team

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next week: DIEP talk (Alexandru Baltag) and LIRa session at *UNUSUAL TIME* (Cedegao Zhang)
by LIRa Seminar 12 Jun '21

12 Jun '21

Dear all, Next Thursday, June 17th, we have two events of interest to the LIRa audience. The first is the DIEP talk of Alexandru Baltag, from 11:00 to 12:30. The second is our LIRa session with Cedegao Zhang, which will take place at 15:00-16:30 (note the ***UNUSUAL TIME*** compared to our regular sessions!). You can find the details for both events, as well as their zoom links, below. ----------------------------------------------------- Date and time: Thursday, June 17th 2021, 11:00-12:30, Amsterdam time. Speaker: Alexandru Baltag (UvA) Title: Group (Ir)Rationality: Can Logic help? Abstract: I present some applications of logical methods (in particular, of so-called dynamic epistemic logics) to the study of emergent phenomena in groups of `agents\', capable of reflection, communication, reasoning, argumentation etc.The main focus on the understanding of belief/preference formation and diffusion in social networks, and on how this affects the group\'s ``epistemic potential\": the ability of the agents to track the truth of the matter (with respect to some given relevant topic). While in some cases, ``wisdom of the crowds\" can increase the epistemic potential, in other situations the group\'s dynamics leads to informational distortions (-- the ``madness of the crowds\": cascades, ``groupthink\", the curse of the committee, pluralistic ignorance, group polarization, doxastic cycles etc). I explain how logic (in combination with probabilistic methods) can be used to provide some explanations for both types of situations, as well as to suggest some partial solutions to informational distortions. Zoom link: https://uva-live.zoom.us/j/85608909905 ---------------------------------------------------- Speaker: Cedegao Zhang (University of California, Berkeley) Date and Time: Thursday, June 17th 2021, 15:00-16:30, Amsterdam time. Venue: online. Title: A Computational Model of Higher-Order Epistemic Reasoning. Abstract. Reasoning about what other people know is an important cognitive ability, known as epistemic reasoning, which has fascinated psychologists, economists, and logicians. We propose a computational model of humans’ epistemic reasoning, including higher-order epistemic reasoning—reasoning about what one person knows about another person’s knowledge—that we test in an experiment using a deductive card game called “Aces and Eights”. Our starting point is the model of perfect higher-order epistemic reasoners given by the framework of dynamic epistemic logic. We modify this idealized model with bounds on the level of feasible epistemic reasoning and stochastic update of a player’s space of possibilities in response to new information. These modifications are crucial for explaining the variation in human performance across different participants and different games in the experiment. Our results demonstrate how research on epistemic logic and cognitive models can inform each other. This is a joint work with Ham Huang and Wesley Holliday. A preprint is available at https://psyarxiv.com/7hkzd/. Recurring zoom link: https://uva-live.zoom.us/j/92907704256?pwd=anY3WkFmQVhLZGhjT2JXMlhjQVl1dz09 (Meeting ID: 929 0770 4256, Passcode: 036024) Hope to see you there! The LIRa team

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LIRa Session *today at 15:00*: Jiatu Li
by LIRa Seminar 10 Jun '21

10 Jun '21

Dear all, This is a reminder that our LIRa session with Jiatu Li today will take place at an UNUSUAL TIME, namely 15:00-16:30. You can find the details of the talk below. We will use our recurring zoom link: https://uva-live.zoom.us/j/92907704256?pwd=anY3WkFmQVhLZGhjT2JXMlhjQVl1dz09 (Meeting ID: 929 0770 4256, Passcode: 036024). Speaker: Jiatu Li Date and Time: Thursday, June 10th 2021, 15:00-16:30, Amsterdam time. Venue: online. Title: Formalization of PAL in Lean. Abstract. Proof assistant (or theorem prover) is a useful tool to organize and check formal mathematical proofs. Despite of several impressive stories, it still seems hopeless for common mathematicians to use it for their daily work. However, it may be handy for logicians in some certain applications, for example, in developing proof systems. In this talk, we will demonstrate a formalization of public announcement logic (including syntax, semantics, a proof system and meta-theorems including soundness and completeness) in Lean theorem prover. We will also discuss in general the potential applications of proof assistant in logic research. Hope to see you there! The LIRa team

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tomorrow: DIEP talk (Casper van Elteren) and LIRa session at *unsual time* (Jiatu Li)
by LIRa Seminar 09 Jun '21

09 Jun '21

Dear all, Tomorrow, June 10th, we have two events of interest to the LIRa audience. The first is the DIEP talk of Casper van Elteren, from 11:00 to 12:30. The second is our LIRa session with Jiatu Li, which will take place on 15:00-16:30 (note the UNUSUAL TIME compared to our regular sessions!). You can find the details for both events, as well as their zoom links, below. ----------------------------------------------------- Date and time: Thursday, June 10th 2021, 11:00-12:30, Amsterdam time. Speaker: Casper van Elteren (UvA) Title: Through the looking glass - Information flows in complex systems Abstract: Understanding dynamical systems is a fundamental problem for the 21st century. Despite the prima facie differences and purposes of many real-world networks, previous research shows several universal characteristics in networks properties such as the small-world phenomenon, fat-tail degree and feedback loops. This has led to the common but often implicit assumption that the connectedness of a node in the network is proportional to its dynamic importance. For example in epidemic research, high degree nodes or \\\"super-spreaders\\\" are associated to dominant epidemic risk and therefore deserve special attention. Yet prior research shows that the shared universality in network characteristics is not shared in the dynamic or functional properties of many real-world systems. In this talk I will explore the relation between local interactions and macroscopic properties of a system through the lens of statistical physics and information theory. In particular, I will show novel methods on determining the so-called driver node in complex systems, and how tipping points can be studied from an information theoretical perspective. (website + slides: https://cvanelteren.github.io/talk/diep2021/) Zoom link: https://uva-live.zoom.us/j/85608909905 ----------------------------------------------------- Speaker: Jiatu Li Date and Time: Thursday, June 10th 2021, 15:00-16:30, Amsterdam time. Venue: online. Title: Formalization of PAL in Lean. Abstract. Proof assistant (or theorem prover) is a useful tool to organize and check formal mathematical proofs. Despite of several impressive stories, it still seems hopeless for common mathematicians to use it for their daily work. However, it may be handy for logicians in some certain applications, for example, in developing proof systems. In this talk, we will demonstrate a formalization of public announcement logic (including syntax, semantics, a proof system and meta-theorems including soundness and completeness) in Lean theorem prover. We will also discuss in general the potential applications of proof assistant in logic research. Recurring zoom link: https://uva-live.zoom.us/j/92907704256?pwd=anY3WkFmQVhLZGhjT2JXMlhjQVl1dz09 (Meeting ID: 929 0770 4256, Passcode: 036024) Hope to see you there! The LIRa team

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next week: DIEP talk (Casper van Elteren) and LIRa session at *unsual time* (Jiatu Li)
by LIRa Seminar 04 Jun '21

04 Jun '21

Dear all, Next Thursday, June 10th, we have two events of interest to the LIRa audience. The first is the DIEP talk of Casper van Elteren, from 11:00 to 12:30. The second is our LIRa session with Jiatu Li, which will take place on 15:00-16:30 (note the UNUSUAL TIME compared to our regular sessions!). You can find the details for both events, as well as their zoom links, below. ----------------------------------------------------- Date and time: Thursday, June 10th 2021, 11:00-12:30, Amsterdam time. Speaker: Casper van Elteren (UvA) Title: Through the looking glass - Information flows in complex systems Abstract: Understanding dynamical systems is a fundamental problem for the 21st century. Despite the prima facie differences and purposes of many real-world networks, previous research shows several universal characteristics in networks properties such as the small-world phenomenon, fat-tail degree and feedback loops. This has led to the common but often implicit assumption that the connectedness of a node in the network is proportional to its dynamic importance. For example in epidemic research, high degree nodes or \"super-spreaders\" are associated to dominant epidemic risk and therefore deserve special attention. Yet prior research shows that the shared universality in network characteristics is not shared in the dynamic or functional properties of many real-world systems. In this talk I will explore the relation between local interactions and macroscopic properties of a system through the lens of statistical physics and information theory. In particular, I will show novel methods on determining the so-called driver node in complex systems, and how tipping points can be studied from an information theoretical perspective. (website + slides: https://cvanelteren.github.io/talk/diep2021/) Zoom link: https://uva-live.zoom.us/j/85608909905 ----------------------------------------------------- Speaker: Jiatu Li Date and Time: Thursday, June 10th 2021, 15:00-16:30, Amsterdam time. Venue: online. Title: Formalization of PAL in Lean. Abstract. Proof assistant (or theorem prover) is a useful tool to organize and check formal mathematical proofs. Despite of several impressive stories, it still seems hopeless for common mathematicians to use it for their daily work. However, it may be handy for logicians in some certain applications, for example, in developing proof systems. In this talk, we will demonstrate a formalization of public announcement logic (including syntax, semantics, a proof system and meta-theorems including soundness and completeness) in Lean theorem prover. We will also discuss in general the potential applications of proof assistant in logic research. Recurring zoom link: https://uva-live.zoom.us/j/92907704256?pwd=anY3WkFmQVhLZGhjT2JXMlhjQVl1dz09 (Meeting ID: 929 0770 4256, Passcode: 036024) Hope to see you there! The LIRa team

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tomorrow: DIEP talk (Velimir Ilić) and regular LIRa session (Guillermo Menéndez Turata)
by LIRa Seminar 02 Jun '21

02 Jun '21

Dear all, Tomorrow, June 3rd, we have two events of interest to the LIRa audience. The first is the DIEP talk of Velimir Ilić, from 11:00 to 12:30. The second is our regular LIRa session with Guillermo Menéndez Turata, from 16:30 to 18:00. You can find the details for both events, as well as their zoom links, below. ----------------------------------------------------- Date and time: Thursday, June 3rd 2021, 11:00-12:30, Amsterdam time. Speaker: Velimir Ilić (Mathematical Institute of the Serbian Academy of Sciences and Arts) Title: An overview and characterization of generalized information measures Abstract: The aim of this talk is to present a comprehensive classification of the main entropic forms introduced in the last fifty years within statistical physics and information theory and to review the fundamental questions about the meaning of information. I will particularly focus on axiomatic approaches to the characterization of various generalizations of the Shannon entropy, such as the Rényi, the Tsallis, the Sharma-Mittal, and the Sharma-Mittal-Taneja entropies, as well as the more general classes of pseudo-additive entropies with a well-defined mathematical and information theoretic structure. Finally, I will point out possible applications of these measures in communication theory, statistical inference and complex systems modeling. Zoom link: https://uva-live.zoom.us/j/85608909905 ----------------------------------------------------- Speaker: Guillermo Menéndez Turata Date and Time: Thursday, June 3rd 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Uniform interpolation from cyclic proofs: the case of modal mu-calculus. Abstract. Uniform interpolation was first established for the modal mu-calculus by D’Agostino and Hollenberg via a combination of semantic and syntactic methods. A natural question is whether a purely syntactical proof of this result, in the style of Pitt’s seminal work on uniform interpolation for intuitionistic logic, can be produced. One possible reason Pitt’s method has not been applied to the modal mu-calculus is that it requires a setting where uniform interpolation can be proved by induction on cut-free derivations in a finitary system. While it is feasible to design cut-free calculi for fixpoint modal logics, they are often infinitary, i.e., derivations may have infinite branches. In this talk we apply Pitt’s technique to the modal mu-calculus and show how to construct uniform interpolants from cyclic derivations in an annotated goal-oriented proof system introduced by Jungteerapanich and Stirling. Recurring zoom link: https://uva-live.zoom.us/j/92907704256?pwd=anY3WkFmQVhLZGhjT2JXMlhjQVl1dz09 (Meeting ID: 929 0770 4256, Passcode: 036024) Hope to see you there! The LIRa team

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