ILLC-LIRa September 2021

illc-lira@list.uva.nl

2 participants
8 discussions

LIRa Session: Johan van Benthem (tomorrow, Thursday, 30 September 16:30)
by LIRa Seminar 29 Sep '21

29 Sep '21

Dear all, We will have our next LIRa session tomorrow, on Thursday, 30 September 16:30. 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: Johan van Benthem (Amsterdam, Stanford & Tsinghua) Date and Time: Thursday, September 30th 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Interleaving Logic and Counting Abstract. Reasoning with generalized quantifiers in natural language combines logical and arithmetical features, transcending divides between qualitative and quantitative. This practice blends with inference patterns in ‘grassroots mathematics’ such as pigeon-hole principles. Our topic is this cooperation of logic and counting, studied with small systems and gradually moving upward. We start with monadic first-order logic with counting. We provide normal forms that allow for axiomatization, determine which arithmetical notions are definable, and conversely, discuss which logical notions can be defined out of arithmetical ones, and what sort of (non-)classical logics are induced. Next we study a series of strengthenings in the same style, including second-order versions, systems with multiple counting, and a new modal logic with counting. As a complement to our fragment approach, we also discuss another way of controlling complexity: changing the semantics of counting to reason about ‘mass’ or other aggregating notions than cardinalities. Finally, we return to natural language, confronting the architecture of our formal systems with linguistic quantifier vocabulary, modules such as monotonicity reasoning, and the procedural semantics via semantic automata. We conclude with some thoughts on further entanglements of logic and counting in formal systems, on rethinking the qualitative/quantitative divide, and on empirical aspects of our findings. Hope to see you there! The LIRa team

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LIRa-related event
by LIRa Seminar 27 Sep '21

27 Sep '21

Dear all, The following event may be interesting to some in the LIRa audience: ---------------------------------------------- This Thursday, the 30th of September at 11am there will be a DIEP seminar with Michel Mandjes on: Title: A diffusion-based analysis of a road traffic network Abstract: In this talk I will discuss an important example of complex networks, namely road traffic networks. I start by giving an overview of the existing literature, distinguishing between microscopic models (describing the stochastic evolution of the position of individual vehicles) and macroscopic models (built around deterministic continuous flows, represented as partial differential equations). Then I argue that the “optimal" model is a compromise between these: we aim at a stochastic model with enough aggregation to make sure that explicit limiting analysis can be performed. The underlying dynamics are consistent with the macroscopic fundamental diagram that describes the functional relation between the vehicle density and velocity. Discretizing space, the model can be phrased in terms of a spatial population process, thus allowing the application of a classical scaling approach. More specifically, it follows that under a diffusion scaling, the vehicle density process can be approximated by an appropriate Gaussian process. This Gaussian approximation can be used to evaluate the travel time distribution between a given origin and destination. Based on joint work with Jaap Storm (VU). Zoom link: https://uva-live.zoom.us/j/85608909905 ---------------------------------------------- The LIRa team

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LIRa Session: Johan van Benthem (Thursday, 30 September 16:30)
by LIRa Seminar 24 Sep '21

24 Sep '21

Dear all, We will have our next LIRa session on Thursday, 30 September 16:30. 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: Johan van Benthem (Amsterdam, Stanford & Tsinghua) Date and Time: Thursday, September 30th 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Interleaving Logic and Counting Abstract. Reasoning with generalized quantifiers in natural language combines logical and arithmetical features, transcending divides between qualitative and quantitative. This practice blends with inference patterns in ‘grassroots mathematics’ such as pigeon-hole principles. Our topic is this cooperation of logic and counting, studied with small systems and gradually moving upward. We start with monadic first-order logic with counting. We provide normal forms that allow for axiomatization, determine which arithmetical notions are definable, and conversely, discuss which logical notions can be defined out of arithmetical ones, and what sort of (non-)classical logics are induced. Next we study a series of strengthenings in the same style, including second-order versions, systems with multiple counting, and a new modal logic with counting. As a complement to our fragment approach, we also discuss another way of controlling complexity: changing the semantics of counting to reason about ‘mass’ or other aggregating notions than cardinalities. Finally, we return to natural language, confronting the architecture of our formal systems with linguistic quantifier vocabulary, modules such as monotonicity reasoning, and the procedural semantics via semantic automata. We conclude with some thoughts on further entanglements of logic and counting in formal systems, on rethinking the qualitative/quantitative divide, and on empirical aspects of our findings. Hope to see you there! The LIRa team

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LIRa Session: Hans Rott (tomorrow, Thursday, 23 September 16:30)
by LIRa Seminar 22 Sep '21

22 Sep '21

Dear all, We will have our next LIRa session tomorrow, on Thursday, 23 September 16:30. 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: Hans Rott Date and Time: Thursday, September 23rd 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Difference-making and 'Because' Abstract. Causes make a difference to their effects, explanantia make a difference to their explananda, reasons make a difference to what they are reasons for. The paradigmatic way of reporting about causal, explanatory or reason relations is in the form of sentences using 'because' or its stylistic variant 'since'. Such sentences thus express that the antecedent makes a difference to the consequent. We suggest to analyze 'because' with the help of a difference-making conditional ». The latter is stronger than the usual suppositional conditional >. A»C can be defined by the conjunction of (i) A>C and (ii) ¬(¬A>C). We show that the logic of difference making can be extended to get a logic for 'C because A' by adding the clauses that (iii) A is true/accepted and (iv) C is true/accepted. We show that under a rather standard analysis of the suppositional conditional, the analysis of 'C because A' reduces to just (ii) and (iv). In other words, an explanation of C by A implies that the explanandum C is true or believed to be true, and it also implies the might conditional 'If ¬A had been the case, ¬C might have been the case.' References: - Eric Raidl, 'Definable conditionals', Topoi 40(1), 2021, 87-105. https://doi.org/10.1007/s11245-020-09704-3 - Hans Rott, 'Difference-making conditionals and the Relevant Ramsey Test', Review of Symbolic Logic, online Dec 2019, https://doi.org/10.1017/S1755020319000674. Hope to see you there! The LIRa team

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LIRa Session: Hans Rott (Thursday, 23 September 16:30)
by LIRa Seminar 17 Sep '21

17 Sep '21

Dear all, We will have our next LIRa session on Thursday, 23 September 16:30. 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: Hans Rott Date and Time: Thursday, September 23rd 2021, 16:30-18:00, Amsterdam time. Venue: online. Title: Difference-making and 'Because' Abstract. Causes make a difference to their effects, explanantia make a difference to their explananda, reasons make a difference to what they are reasons for. The paradigmatic way of reporting about causal, explanatory or reason relations is in the form of sentences using 'because' or its stylistic variant 'since'. Such sentences thus express that the antecedent makes a difference to the consequent. We suggest to analyze 'because' with the help of a difference-making conditional ». The latter is stronger than the usual suppositional conditional >. A»C can be defined by the conjunction of (i) A>C and (ii) ¬(¬A>C). We show that the logic of difference making can be extended to get a logic for 'C because A' by adding the clauses that (iii) A is true/accepted and (iv) C is true/accepted. We show that under a rather standard analysis of the suppositional conditional, the analysis of 'C because A' reduces to just (ii) and (iv). In other words, an explanation of C by A implies that the explanandum C is true or believed to be true, and it also implies the might conditional 'If ¬A had been the case, ¬C might have been the case.' References: - Eric Raidl, 'Definable conditionals', Topoi 40(1), 2021, 87-105. https://doi.org/10.1007/s11245-020-09704-3 - Hans Rott, 'Difference-making conditionals and the Relevant Ramsey Test', Review of Symbolic Logic, online Dec 2019, https://doi.org/10.1017/S1755020319000674. Hope to see you there! The LIRa team

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LIRa Session: Sonja Smets (Tomorrow, Thursday 16 September at 16:30)
by LIRa Seminar 15 Sep '21

15 Sep '21

Dear all, Tomorrow we will have our next LIRa session. 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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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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ILLC-LIRa September 2021