ILLC-LIRa September 2022

illc-lira@list.uva.nl

1 participants
5 discussions

LIRa session: Lingyuan Ye (Thursday, 6 October 16:30)
by LIRa Seminar 30 Sep '22

30 Sep '22

Dear all, We will have our next LIRa session on Thursday, 6 October 16:30. This will be a hybrid session. If you want to attend online, please use our recurring zoom link: https://uva-live.zoom.us/j/89230639823?pwd=YWJuSnJmTDhXcWhmd1ZkeG5zb0o5UT09 (Meeting ID: 892 3063 9823, Passcode: 421723) You can find the details of the talk below. Speaker: Lingyuan Ye Date and Time: Thursday, October 6th 2022, 16:30-18:00 Venue: F1.15 and online. Title: Unification of Semantics of Modal Logic via Topological Categories Abstract. In this talk we will provide a unifying description of different types of semantics of modal logic found in the literature, via topological categories. In particular, we will show how the natural extensions of basic modal logic, including multi-agency, epistemic dependence, group agency, and logical dynamics, could be naturally associated to various semantic structures within topological categories. The unifying description and such correspondence would allow us to generalise the interpretation of these extensions simultaneously to any semantics of modal logic, and prove certain structural results about them in the style of categorical logic. Hope to see you there! The LIRa team

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LIRa session: Thomas Randriamahazaka (tomorrow, Thursday, 29 September 16:30)
by LIRa Seminar 28 Sep '22

28 Sep '22

Dear all, We will have our next LIRa session tomorrow, on Thursday, 29 September 16:30. This will be a hybrid session. If you want to attend online, please use our recurring zoom link: https://uva-live.zoom.us/j/89230639823?pwd=YWJuSnJmTDhXcWhmd1ZkeG5zb0o5UT09 (Meeting ID: 892 3063 9823, Passcode: 421723) You can find the details of the talk below. Speaker: Thomas Randriamahazaka (University of St Andrews) Date and Time: Thursday, September 29th 2022, 16:30-18:00 Venue: F1.15 and online. Title: Aboutness and partiality: a duality-theoretic perspective. Abstract. A familiar story identifies propositions with sets of possible worlds. This can be understood as the semantic upshot of Stone duality, once it is accepted that propositions form a Boolean algebra. However, possible world semantics is often said to be too coarse-grained to account for some semantic phenomena. To solve this problem, it is possible to distinguish between two popular hyperintensional strategies. The first one is to supplement the space of possible worlds by a mereology of topics and to individuate propositions as pairs consisting of a set of possible worlds and a topic. The second one is to replace possible worlds by partial states. The goal of this talk is to identify a bridge between these two strategies using the tools of duality theory. From an algebraic point of view, the first strategy can be seen as the application of the construction known as Plonka sum. More precisely, the algebra of propositions can be described as the Plonka sum of Boolean algebras over the semilattice of topics. The main result of this talk is the description of the topological dual of the Plonka sum construction, dubbed co-Plonka sum. To do so, a new, weaker notion of topological space will be needed. This dual construction will allow us to lift Stone duality through the Plonka sum and have a description of the dual space of the algebra of propositions. Just like the points of the dual Stone space of a Boolean algebra can be understood as possible worlds, the points of the dual space of the algebra of propositions are best described as partial states, linking the first and the second strategies. Hope to see you there! The LIRa team

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LIRa session: Thomas Randriamahazaka (Thursday, 29 September 16:30)
by LIRa Seminar 23 Sep '22

23 Sep '22

Dear all, We will have our next LIRa session on Thursday, 29 September 16:30. This will be a hybrid session. If you want to attend online, please use our recurring zoom link: https://uva-live.zoom.us/j/89230639823?pwd=YWJuSnJmTDhXcWhmd1ZkeG5zb0o5UT09 (Meeting ID: 892 3063 9823, Passcode: 421723) You can find the details of the talk below. Speaker: Thomas Randriamahazaka (University of St Andrews) Date and Time: Thursday, September 29th 2022, 16:30-18:00 Venue: F1.15 and online. Title: Aboutness and partiality: a duality-theoretic perspective. Abstract. A familiar story identifies propositions with sets of possible worlds. This can be understood as the semantic upshot of Stone duality, once it is accepted that propositions form a Boolean algebra. However, possible world semantics is often said to be too coarse-grained to account for some semantic phenomena. To solve this problem, it is possible to distinguish between two popular hyperintensional strategies. The first one is to supplement the space of possible worlds by a mereology of topics and to individuate propositions as pairs consisting of a set of possible worlds and a topic. The second one is to replace possible worlds by partial states. The goal of this talk is to identify a bridge between these two strategies using the tools of duality theory. From an algebraic point of view, the first strategy can be seen as the application of the construction known as Plonka sum. More precisely, the algebra of propositions can be described as the Plonka sum of Boolean algebras over the semilattice of topics. The main result of this talk is the description of the topological dual of the Plonka sum construction, dubbed co-Plonka sum. To do so, a new, weaker notion of topological space will be needed. This dual construction will allow us to lift Stone duality through the Plonka sum and have a description of the dual space of the algebra of propositions. Just like the points of the dual Stone space of a Boolean algebra can be understood as possible worlds, the points of the dual space of the algebra of propositions are best described as partial states, linking the first and the second strategies. Hope to see you there! The LIRa team

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LIRa session: Zoé Christoff (tomorrow, Thursday, 15 September 16:30)
by LIRa Seminar 14 Sep '22

14 Sep '22

Dear all, We will have the first LIRa session of the new semester tomorrow, on Thursday, 15 September at 16:30. This will be a hybrid session. If you want to attend online, please use our recurring zoom link: https://uva-live.zoom.us/j/89230639823?pwd=YWJuSnJmTDhXcWhmd1ZkeG5zb0o5UT09 (Meeting ID: 892 3063 9823, Passcode: 421723) You can find the details of the talk below. Speaker: Zoé Christoff (University of Groningen) Date and Time: Thursday, September 15th 2022, 16:30-18:00 Venue: room F1.15 at ILLC (NIKHEF building) and online / hybrid Title: Reasoning about Cascading Ability in Social Networks (joint work with Thomas Ågotnes) Abstract. We propose a coalition logic to reason about the power of influence of groups of agents in social networks. We focus on threshold models, where agents are influenced into adopting a new product or behaviour as soon as enough of their direct network-neighbours have adopted it already. We introduce the syntax and semantics and illustrate how it captures the ability of (groups of) agents to trigger cascading effects in the network. We discuss some properties featured by the new logic, some of which are directly inherited from the underlying standard Coalition Logic, and some that are novel. Hope to see you there! The LIRa team

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LIRa session: Zoé Christoff (Thursday, 15 September 16:30)
by LIRa Seminar 09 Sep '22

09 Sep '22

Dear all, Welcome back after the summer break! We will start into the new academic year with our first LIRa session next week Thursday, 15 September at 16:30. This will be a *hybrid* session. You are invited to join us on location, or you may attend online using this (new!) zoom link: https://uva-live.zoom.us/j/89230639823?pwd=YWJuSnJmTDhXcWhmd1ZkeG5zb0o5UT09 (Meeting ID: 892 3063 9823, Passcode: 421723) You can find the details of the talk below. Speaker: Zoé Christoff (University of Groningen) Date and Time: Thursday, September 15th 2022, 16:30-18:00 Venue: room F1.15 at ILLC (NIKHEF building) and online / hybrid Title: Reasoning about Cascading Ability in Social Networks (joint work with Thomas Ågotnes) Abstract. We propose a coalition logic to reason about the power of influence of groups of agents in social networks. We focus on threshold models, where agents are influenced into adopting a new product or behaviour as soon as enough of their direct network-neighbours have adopted it already. We introduce the syntax and semantics and illustrate how it captures the ability of (groups of) agents to trigger cascading effects in the network. We discuss some properties featured by the new logic, some of which are directly inherited from the underlying standard Coalition Logic, and some that are novel. Hope to see you there! The LIRa team

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ILLC-LIRa September 2022