ILLC-LIRa November 2019

illc-lira@list.uva.nl

1 participants
6 discussions

LIRa session: Michael Mäs
by LIRa Seminar 29 Nov '19

29 Nov '19

Dear all, We will have our next session on Thursday, December 5th. Our speaker is Michael Mäs, and you can find the details of the talk below: Speaker: Michael Mäs (Department of Sociology and the ICS, University of Groningen) Date and Time: Thursday, December 5th 2019, 16:30-18:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Do Filter Bubbles Foster Opinion Polarization? Abstract. Political events such as the Brexit referendum, the election of Donald Trump, and the success of populists in democratic elections have sparked public and scholarly discussion about the effects of online-communication technology on public debate and collective decision-making. In particular, it has been warned that personalization algorithms installed in online social-networks, and search engines contribute to the formation of so-called “filter bubbles”. These bubbles isolate users from information that challenges their views and expose them to content that is in line with their opinions. It has been warned that this contributes to opinion polarization, a dynamic where competing political camps develop increasingly opposing political views. Here, I summarize research on the relationship between personalization and polarization. While I echo the warning that personalization can affect societal processes, I demonstrate that we leap to conclusions when we propose that personalization is responsible for increased polarization. Based on results from formal modeling work, I argue that we lack crucial empirical insight into the microprocess of social influence and the aggregation of repeated influence to macroprocesses of opinion polarization. I call for more research on communication in online environments, pointing to the potential of approaches that combine rigorous theoretical modeling with the emerging field of computational social-science. Hope to see you there! The LIRa team

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LIRa Session: Rasmus Rendsvig
by LIRa Seminar 27 Nov '19

27 Nov '19

Dear all, Tomorrow, we will have our next LIRa session at 13:00. Please, find the details below: Speaker: Rasmus Rendsvig (Center for Information and Bubble Studies, University of Copenhagen) Date and Time: Thursday, November 28th 2019, 13:00-14:30 (NOTE THE UNUSUAL TIME) Venue: ILLC Seminar Room F1.15, Science Park 107. Title: A Topological Perspective on Common Knowledge and on Dynamic Epistemic Logic. Abstract. This talk discusses how analyzing logical dynamics as unfolding in a topological space provides an interesting perspective. The talk falls in two parts. The first part exemplifies a topological analysis by taking a look at the attainment of common knowledge. Common knowledge, as is well known, is not attainable in finite time by unreliable communication, thus hindering perfect coordination. Focusing on the coordinated attack problem modeled using dynamic epistemic logic, this part asks “If the generals may communicate indefinitely, will they then converge to a state of common knowledge?” We answer by making precise and showing the following: Common knowledge is attainable if, and only if, we do not care about common knowledge. The analysis relies on a particular interpretation of qualitative distance. The first part will motivate one specific such interpretation, which in turn motivates working with a particular topology, known as the Stone topology. The second part of the talk takes an abstract view of functions and relations on Stone topological spaces---one realm inhabited by many model transformations known from dynamic epistemic logic---and discusses connections between recursive reduction law existence, computability and continuity. Hope to see you there! The LIRa team

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Next week: Workshop for Dick de Jongh and (unusual time) LIRa
by LIRa Seminar 22 Nov '19

22 Nov '19

Dear all, On Wednesday 27 November 2019, the ILLC is organising a workshop and reception to celebrate Dick de Jongh\'s 80th birthday. The workshop will take place in the ILLC Common Room, to be followed by a Reception (in the same place). For details, please visit http://festschriften.illc.uva.nl/D80/. On Thursday, at 13:00 (NOTE THE UNUSUAL TIME), we will have our next LIRa session. Our speaker is Rasmus Rendsvig and you can find the details below: Speaker: Rasmus Rendsvig (Center for Information and Bubble Studies, University of Copenhagen) Date and Time: Thursday, November 28th 2019, 13:00-14:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: A Topological Perspective on Common Knowledge and on Dynamic Epistemic Logic. Abstract. This talk discusses how analyzing logical dynamics as unfolding in a topological space provides an interesting perspective. The talk falls in two parts. The first part exemplifies a topological analysis by taking a look at the attainment of common knowledge. Common knowledge, as is well known, is not attainable in finite time by unreliable communication, thus hindering perfect coordination. Focusing on the coordinated attack problem modeled using dynamic epistemic logic, this part asks “If the generals may communicate indefinitely, will they then converge to a state of common knowledge?” We answer by making precise and showing the following: Common knowledge is attainable if, and only if, we do not care about common knowledge. The analysis relies on a particular interpretation of qualitative distance. The first part will motivate one specific such interpretation, which in turn motivates working with a particular topology, known as the Stone topology. The second part of the talk takes an abstract view of functions and relations on Stone topological spaces—one realm inhabited by many model transformations known from dynamic epistemic logic—and discusses connections between recursive reduction law existence, computability and continuity. The LIRa team

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Joint LoC-LIRa Session: Barbara Vetter
by LIRa Seminar 08 Nov '19

08 Nov '19

Dear all, The next LIRa session (November 14th) will be joint with the Logic of Conceivability seminar. The speaker is Barbara Vetter and you can find more below: Speaker: Barbara Vetter (Freie Universität Berlin) Date and Time: Thursday, November 14th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: An Agency-based Approach to Modal Knowledge. Abstract. How do we know about possibility and necessity? Philosophical work on this question divides into rationalist approaches, which takes the source of our modal knowledge to be in some important ways a priori, and empiricist approaches, which take modal knowledge to be continuous with our empirical knowledge of the world. In this talk, I will present and motivate a deeply empiricist approach with three distinctive features. First, it locates the roots of our modal thought and knowledge in the experience of our own agency in the world. Second, the approach is ambitious in that it takes this starting point in agency to be the only distinctive feature of modal thought and knowledge: everything that we know about modality beyond the context of action is a matter of applying standard methods of induction, abduction, and so forth. Third, the approach is property-based, in that it takes our modal thought and knowledge to be primarily about the modal properties of objects.. Hope to see you there! The LIRa team

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LIRa Session: Natasha Alechina
by LIRa Seminar 06 Nov '19

06 Nov '19

Dear all, Tomorrow we will have our next LIRa session. Please, find the details below: Speaker: Natasha Alechina (University of Nottingham) Date and Time: Thursday, November 7th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: On the relative expressivity of Group and Coalition Announcement Logics. Abstract. Group Announcement Logic (GAL) and Coalition Announcement Logic (CAL) were proposed to study effects of public announcements by groups of agents on knowledge in multiagent systems. Both logics have operators that quantify over such announcements. In GAL, it is possible to express that `a group of agents G has a (truthful) announcement such that after this announcement, some property A holds’; for example, A may involve some agents in G gaining additional knowledge, while agents outside G remain ignorant. In CAL, the meaning of the coalition announcement operator is subtly different: it says that ` G has an announcement such that, whatever else the agents outside G announce simultaneously, some property A is guaranteed to hold after the joint announcement\'. It has been open for some time whether GAL and CAL are equally expressive. We show that this is not the case: there is a property expressible in GAL that is not expressible in CAL. It is still an open question whether CAL is subsumed by GAL, or whether the two logics have incomparable expressive power. Hope to see you there! The LIRa team

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LIRa Session: Natasha Alechina
by LIRa Seminar 01 Nov '19

01 Nov '19

Dear all, We will have our next session on Thursday, November 7th. Our speaker is Natasha Alechina, and you can find the details of the talk below: Speaker: Natasha Alechina (University of Nottingham) Date and Time: Thursday, November 7th 2019, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: On the relative expressivity of Group and Coalition Announcement Logics. Abstract. Group Announcement Logic (GAL) and Coalition Announcement Logic (CAL) were proposed to study effects of public announcements by groups of agents on knowledge in multiagent systems. Both logics have operators that quantify over such announcements. In GAL, it is possible to express that `a group of agents G has a (truthful) announcement such that after this announcement, some property A holds’; for example, A may involve some agents in G gaining additional knowledge, while agents outside G remain ignorant. In CAL, the meaning of the coalition announcement operator is subtly different: it says that ` G has an announcement such that, whatever else the agents outside G announce simultaneously, some property A is guaranteed to hold after the joint announcement\'. It has been open for some time whether GAL and CAL are equally expressive. We show that this is not the case: there is a property expressible in GAL that is not expressible in CAL. It is still an open question whether CAL is subsumed by GAL, or whether the two logics have incomparable expressive power. Hope to see you there! The LIRa team

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ILLC-LIRa November 2019