ILLC-LIRa

illc-lira@list.uva.nl

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582 discussions

Tomorrow LIRa Session with Alexandru Baltag
by LIRa Seminar 11 Apr '18

11 Apr '18

Dear all, Tomorrow we will have our next LIRa Session. Speaker: Alexandru Baltag Date and Time: Thursday, April 12th 2018, 16:30-18:00 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Some Thoughts on the Logic of Imprecise Observations Abstract: This talk is based on joint work with Johan van Benthem. We propose a dynamic-epistemic analysis of perceptual knowledge, taking as our starting point the paradoxes posed by Williamson\'s Margin of Error (MoE) principle. We argue that, contrary to initial intuitions, the specific entanglement between epistemic accessibility and perceptual closeness, that is claimed in the MoE principle, is untenable and inconsistent with daily experience and the theory of measurements. However, we think that it still contains valuable intuitions for a joint logic of closeness and knowledge, whose contours we develop, by placing structured observational events at center stage. In particular, our analysis explains how imprecise observation can lead to higher-precision knowledge, but also how can we find more plausible formalizations of MoE intuitions, in terms of principles limiting what can be learnt by perceptual observations. Hope to see you there! The LIRa team

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Call for Abstracts: Colloquium on Reasoning in Social Context, Amsterdam 31 May - 2 June
by LIRa Seminar 06 Apr '18

06 Apr '18

Colloquium of the Royal Netherlands Academy of Arts and Sciences on: REASONING IN SOCIAL CONTEXT 31 MAY - 2 JUNE, 2018 Trippenhuis Building, Kloveniersburgwal 29, 1011 JV Amsterdam https://sites.google.com/site/reasoningcolloquium/home CALL FOR ABSTRACTS: We welcome submissions for short presentations on the theme of the colloquium. Submissions of 1 page abstracts (in pdf format) should be uploaded on the easychair submission webpage (https://easychair.org/conferences/?conf=reasoning2018), by May 1st 2018. Authors will be notified of acceptance by May 7th 2018. DEADLINE ABSTRACTS: May 1st, 2018. THEME: The central question that we address in this colloquium focusses on the models that can represent the first level and higher-level beliefs of agents, their knowledge as well as the changes of beliefs and knowledge in a community. We aim to understand the nature of the logic that can model how the beliefs of agents in a group are affected by the opinions and belief changes of others in a social network. The logical study of belief formation, belief revision and knowledge updates in a community is gaining importance as these logical methods can be applied to a number of real life scenarios in the social sciences. A number of logical systems are already available to deal with the complex multi-agent scenarios in which an individual, or groups of agents, update their knowledge and change their beliefs. An important player in this field is dynamic epistemic logic, which refers to a collection of logical systems that are united in their method to deal with information dynamics. Guided by the methodology of dynamic epistemic logic, we approach the questions at this colloquium from an interdisciplinary angle. As such we welcome any insights on the topic coming from areas such as Game Theory, Belief Revision Theory, Formal Epistemology, Social Science, Network Theory, Cognitive Science and AI (multi-agent systems). The overall focus includes (but is not restricted to) the following topics: _ formal representations of higher-order belief, knowledge and belief revision strategies _ epistemic and doxastic influence _ belief merge _ information flow in social networks _ evidential support of epistemic attitudes _ trust and trust revision The LIRa team

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Tomorrow LIRa Session with Aldo Ramirez-Abarca
by LIRa Seminar 04 Apr '18

04 Apr '18

Dear all, Tomorrow we will have our next LIRa Session. Speaker: Aldo Ramirez-Abarca Date and Time: Thursday, April 5th 2018, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Playing with stit-fire Abstract: Stit logic has a strong connection to game theory. It is well known that some of the by-now established stit semantics were heavily inspired by game theoretical notions at their conception, under a clear correlation between ‘strategies’, on one hand, and ‘actions’, on the other. Furthermore, standards of game theory (such as utilities and dominance of strategies) have been explicitly imported into stit semantics to model different aspects of agentive behavior. A typical example is Horty’s (2001) stit formalization of obligation using weak dominance of strategies. It comes as no surprise, then, that the basic components for games (outcomes and individual/group/joint strategies) can be formalized with stit logic. This leads to what we may call game models for a stit language of individual/collective action (van Benthem & Pacuit, 2014; van de Putte, Tamminga, & Duijf, 2017). As it turns out, game models are in logical correspondence with a particular subclass of basic stit models (van de Putte, Tamminga, & Duijf, 2017). If we extend the basic stit language with both obligation and knowledge/belief operators, then, we can formalize traditional concepts found in richer representations of games (rationality, common knowledge, ex-interim/ex-ante/ ex-post knowledge, perfect/imperfect information, extensive-form-information games, uniformity of strategies, expected utility, solution concepts, etc.). The advantage of such a formalization is two-fold: in the game-theory-to-stit direction, it opens the door to producing highly applicable deontic epistemic/doxastic stit logics with intuitions grounded on the preexisting game-theoretical literature; in the stit-to-game-theory direction, it allows us to look for expressive axiomatizations of games, with syntactic formulas corresponding to complex semantic formulations of game constraints. In this talk, I will present an overview of the main results that evidence the connection between stit logic and game theory, and I will address a few proposals to further the use of this connection. Hope to see you there! The LIRa team

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Tomorrow LIRa Session with Zeinab Bakhtiari
by LIRa Seminar 21 Mar '18

21 Mar '18

Dear all, Tomorrow we will have our next LIRa session. Speaker: Zeinab Bakhtiari Date and Time: Thursday, March 22nd 2018, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: How does uncertainty about other voters determine a strategic vote? Abstract. In this talk, we discuss a framework for strategic voting when a voter may lack knowledge about the preferences of other voters, or about other voters\' knowledge about her own preference. In this setting, we define notions of manipulation, equilibrium, and dominance, under uncertainty. We provide scenarios wherein the profile of true preferences is the same but the equilibrium profiles are different because the voters have different knowledge about other voters. We also model actions that change such uncertainty about preferences, such as a voter revealing her preference. We show that some forms of manipulation and equilibrium are preserved under such uncertainty updates and others not. We then formalize epistemic voting terminology in a logic. Our aim is to provide the epistemic background for the analysis and design of voting rules that incorporate uncertainty. . Hope to see you there! The LIRa team

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Thursday LIRa Session with Zeinab Bakhtiari
by LIRa Seminar 19 Mar '18

19 Mar '18

Dear all, This Thursday we will have our next LIRa session. Speaker: Zainab Bakhtiari Date and Time: Thursday, March 22nd 2018, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: How does uncertainty about other voters determine a strategic vote? Abstract. In this talk, we discuss a framework for strategic voting when a voter may lack knowledge about the preferences of other voters, or about other voters\' knowledge about her own preference. In this setting, we define notions of manipulation, equilibrium, and dominance, under uncertainty. We provide scenarios wherein the profile of true preferences is the same but the equilibrium profiles are different because the voters have different knowledge about other voters. We also model actions that change such uncertainty about preferences, such as a voter revealing her preference. We show that some forms of manipulation and equilibrium are preserved under such uncertainty updates and others not. We then formalize epistemic voting terminology in a logic. Our aim is to provide the epistemic background for the analysis and design of voting rules that incorporate uncertainty. . Hope to see you there! The LIRa team

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Tomorrow LIRa Session with Martha Lewis
by LIRa Seminar 14 Mar '18

14 Mar '18

Dear all, Tomorrow we will have our next LIRa session. Speaker: Martha Lewis Date and Time: Thursday, March 15th 2018, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Interacting Conceptual Spaces Abstract: We apply the categorical compositional scheme of (Coecke et al 2010) to conceptual space models of cognition. In order to do this we introduce a new category to describe conceptual spaces. We use this category as a new setting for categorical compositional semantics, emphasizing the convex structure important to conceptual space applications. We show how conceptual spaces for composite types such as adjectives and verbs can be constructed. We illustrate this new model on detailed examples. Hope to see you there! The LIRa team

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Tomorrow LIRa Session with Jan Broersen
by LIRa Seminar 07 Mar '18

07 Mar '18

Dear all, Tomorrow we will have our next LIRa seminar. Speaker: Jan Broersen (Utrecht University) Date and Time: Thursday, March 8th 2018, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: In search for a backward looking interventionist stit semantic. Abstract. In this talk I am interested in coming to a modal logic semantics for backward looking responsibility. I will discuss the so called \'achievement\' stit and try to amend its semantics to take interventions into account. I will discuss the attempt using a puzzle about causal contributions and responsibility in a two agent setting: the dessert example [McLaughlin, 1925]. The work is still in its initial phase and at this point it is not even clear yet if the semantics I aim at admits a proper formal description. Hope to see you there! The LIRa team

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Thursday session with Jana Wagemaker
by LIRa Seminar 27 Feb '18

27 Feb '18

Dear all, This Thursday we will have our next LIRa session. Speaker: Jana Wagemaker Date and Time: Thursday, March 1st 2018, 16:00-17:30 Venue: ILLC Seminar Room F1.15, Science Park 107. Title: Gossip in NetKAT. Abstract. In this talk I will discuss my MoL thesis, where I combined the study of NetKAT with the study of dynamic gossip. NetKAT is a sound and complete network programming language based on Kleene algebra with tests, originally used to describe packets traveling through networks. It has a coalgebraic decision procedure deciding NetKAT equivalences. Dynamic gossip is a field in which it is studied how information spreads through a gossip graph, where the links in the gossip graph are changeable (dynamic). So far no sound and complete logic is available that describes dynamic gossip in a satisfactory way. In this talk we will discuss NetKAT in detail, and then explore the application of NetKAT to dynamic gossip. We will see that a change of perspective on NetKAT in which we keep track of the state of the switches in a network allows us to use NetKAT to model the Learn New Secrets Protocol, which is one of many gossip protocols. The addition to NetKAT to keep track of the state of switches is formalized and shown to remain sound and complete with respect to the packet-processing model. It is shown that the Dynamic Gossip notions of weak successfulness, strong successfulness and sun graph are formalizable in NetKAT and that an important theorem from Dynamic Gossip is also a theorem of NetKAT. Hope to see you there! The LIRa team

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Thursday Session: Dominik Klein
by LIRa Seminar 19 Feb '18

19 Feb '18

Dear all, This Thursday we will have our next LIRa session. Speaker: Dominik Klein (University of Bayreuth) Date and Time: Thursday, February 22nd 2018, 16:00-17:30 Venue: KdVI Seminar Room F3.20, Science Park 107. Title: In the Long Run we’re all Dead: On Kripke Models, Iterated Updates and Dynamic Systems. Abstract. In this talk, we explore the universe of iterated product updates. The talk has two main components. In the first part, we show how iterated product updates can be understood as a dynamic system. In particular, we equip the space of Kripke models with a metric and prove the resulting topology compact. We then show that product updates are continuous with respect to this metric, allowing to understand iterated updates as a discrete time dynamical systems. In the second part of the talk, we apply this apparatus to the case of iterated updates with one and the same event model. There, we expand on a result by Sadzik (2006) that answered a hypothesis by Johan van Benthem to the negative. Sadzik showed that there are pairs of a Kripke Model M and an event model E, such that the process of repeatedly updating M with E never stabilizes nor becomes cyclic. Using our metric based apparatus, we show that Sadzik’s example does, however, stabilize in the infinite, i.e. that the sequence converges to a unique limit point. In fact, we determine a set of conditions on E, the event model, under which iterated update converges in the limit. Finally, we show that Sadzik’s result has an infinite counterpart: There are event models E that, when iteratedly applied to a suitable Kripke model M, display nontrivial limit behavior. They do not converge to a single point nor a limit cycle in the infinite. This is joint work with Rasmus Rendsvig. Hope to see you there! The LIRa team

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Thursday LIRa Session with Alessandro Giordani
by LIRa Seminar 14 Feb '18

14 Feb '18

Dear all, Tomorrow we will have our next LIRa session. Speaker: Alessandro Giordani (Catholic University of Milan) Date and Time: Thursday, February 15th 2018, 16:30-18:00 Venue: KdVI Seminar Room F3.20, Science Park 107. Title: Contrastive Epistemic Logic. Abstract. In standard epistemic logic we assume that knowledge at a world w can be represented as a set E(w) of epistemic scenarios, the ones that are indistinguishable by virtue of the agent’s body of evidence, and that a proposition is known at w provided that all the scenarios in this set are worlds in which that proposition holds, that is E(w) ⊆ [p], where [p] is the set of scenarios where p holds. This immediately implies that knowledge is closed under logical implication, so that it is impossible for an agent to know that p without knowing all the logical consequences of p. Both the basic semantic idea and the closure principle are put into question in contemporary epistemology since, if knowledge is defined along these lines, we can hardly know something, being typically unable to rule out all the epistemic scenarios in which a proposition is false. As a consequence, within the current epistemological debate the idea is explored that an agent can know a proposition even if her evidence set E(w) is not included in [p]. One of the prominent standpoints in this debate is Contrastivism: the position according to which to know that p coincides with knowing that this proposition is the correct answer to a certain question against a set of alternative answers, so that to know is to know the answer to a context-defining question. In the present talk I propose a coherent system of contrastive epistemic logic and show how it can be used to assess the main contrastivist thesis concerning the essence of knowledge. Hope to see you there! The LIRa team

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