{"id":4168,"date":"2020-11-18T10:55:37","date_gmt":"2020-11-18T09:55:37","guid":{"rendered":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/?p=4168"},"modified":"2022-01-18T08:43:49","modified_gmt":"2022-01-18T07:43:49","slug":"lira-grolog-logic-afternoon","status":"publish","type":"post","link":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/2020\/11\/lira-grolog-logic-afternoon\/","title":{"rendered":"LIRa\/GroLog Logic Afternoon: Zo\u00e9 Christoff and Ayb\u00fcke \u00d6zg\u00fcn"},"content":{"rendered":"<p>Speakers: <span class=\" aw5Odc\"><a class=\"XqQF9c\" href=\"https:\/\/www.google.com\/url?q=https%3A%2F%2Fzoechristoff.com%2F&amp;sa=D&amp;sntz=1&amp;usg=AFQjCNHOJNtJTaTOmxS4-d2N3XgEnBmn6g\" target=\"_blank\" rel=\"noopener noreferrer\">Zo\u00e9 Christoff<\/a><\/span> (University of Groningen) and Ayb\u00fcke \u00d6zg\u00fcn (University of Amsterdam)<\/p>\n<p>Date and Time: Thursday, December&nbsp;3rd 2020, 15:30-17:30, <a href=\"https:\/\/www.timeanddate.com\/time\/zone\/netherlands\/amsterdam\" target=\"_blank\" rel=\"noopener noreferrer\">Amsterdam time<\/a>.<\/p>\n<p>Schedule:<\/p>\n<ul class=\"n8H08c UVNKR\">\n<li class=\"TYR86d zfr3Q\" dir=\"ltr\">\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">15:30 Arrival<\/p>\n<\/li>\n<li class=\"TYR86d zfr3Q\" dir=\"ltr\">\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">15:45 First talk<\/p>\n<\/li>\n<li class=\"TYR86d zfr3Q\" dir=\"ltr\">\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">16:30 Break<\/p>\n<\/li>\n<li class=\"TYR86d zfr3Q\" dir=\"ltr\">\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">16:45 Second talk<\/p>\n<\/li>\n<li class=\"TYR86d zfr3Q\" dir=\"ltr\">\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">17:30 Drinks<\/p>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p>Venue: <strong><a href=\"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/guidelines-for-online-sessions\/\">online<\/a><\/strong>.<\/p>\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\"><strong>Zo\u00e9 Christoff<\/strong>: <em>Group Knowledge in Epistemic Logic with Names <\/em><\/p>\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">(joint work with Marta B\u00edlkov\u00e1 and Olivier Roy)<\/p>\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">In many situations, we refer to a group of agents using a label, say &#8220;Trump supporters&#8221; or &#8220;trolls&#8221;, without knowing exactly who the members of the group are. Sometimes, we even fail to know whether we, ourselves, are members of a given group. Yet, epistemic logic typically comes with the simplifying assumption that group membership is common knowledge among the entire population. In 1993 already, Grove and Halpern introduced a generalized epistemic logic relaxing this assumption and replacing the usual indexes to denote agents with abstract names that can have different referents, both individuals or groups, in different possible worlds. In that generalized framework, they replace the standard K_i modalities with modalities of the form S_n and E_n, for &#8220;someone with name n knows&#8221; and &#8220;everyone with name n knows&#8221;, respectively. In our current work, we discuss extensions of this generalized logic with group modalities for common knowledge and distributed knowledge.<\/p>\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">Reference: A. J. Grove and J. Y. Halpern. Naming and Identity in Epistemic Logics Part I: The Propositional Case. Journal of Logic and Computation, 3(4):345\u2013378, 08, 1993.<\/p>\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\"><strong>Ayb\u00fcke \u00d6zg\u00fcn<\/strong>: <em>Uncertainty about Evidence<\/em><\/p>\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">We develop a logical framework for reasoning about knowledge and evidence in which the agent may be uncertain about how to interpret their evidence. Rather than representing an evidential state as a fixed subset of the state space, our models allow the set of possible worlds that a piece of evidence corresponds to to vary from one possible world to another, and therefore itself be the subject of uncertainty. Such structures can be viewed as (epistemically motivated) generalizations of topological spaces. In this context, there arises a natural distinction between what is <em>actually<\/em> entailed by the evidence and what the agent <em>knows <\/em>is entailed by the evidence&#8212;with the latter, in general, being much weaker. We provide a sound and complete axiomatization of the corresponding bi-modal logic of knowledge and evidence entailment, and investigate some natural extensions of this core system, including the addition of a belief modality and its interaction with evidence interpretation and entailment, and the addition of a \u201cknowability&#8221; modality interpreted via a (generalized) interior operator.<\/p>\n<p class=\"CDt4Ke zfr3Q\" dir=\"ltr\">This is joint work with Adam Bjorndahl.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Speakers: Zo\u00e9 Christoff (University of Groningen) and Ayb\u00fcke \u00d6zg\u00fcn (University of Amsterdam)<br \/>\nDate and Time: Thursday, December&nbsp;3rd 2020, 15:30-17:30, Amsterdam time.<br \/>\nSchedule:<\/p>\n<p>15:30 Arrival<\/p>\n<p>15:45 First talk<\/p>\n<p>16:30 Break<\/p>\n<p>16:45 Second talk<\/p>\n<p>17:30 Drinks<\/p>\n<p>&nbsp;<br \/>\nVenue: online.<br \/>\nZo\u00e9 Christoff: Group Knowledge in Epistemic Logic with Names<br \/>\n(joint work with Marta B\u00edlkov\u00e1 and Olivier Roy)<br \/>\nIn many situations, we refer to a group of agents using a [&#8230;]<\/p>\n","protected":false},"author":14,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-4168","post","type-post","status-publish","format-standard","hentry","category-events"],"_links":{"self":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/posts\/4168","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/users\/14"}],"replies":[{"embeddable":true,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/comments?post=4168"}],"version-history":[{"count":5,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/posts\/4168\/revisions"}],"predecessor-version":[{"id":4608,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/posts\/4168\/revisions\/4608"}],"wp:attachment":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/media?parent=4168"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/categories?post=4168"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/tags?post=4168"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}