The next event is on Thursday, April 9th:<\/p>
Speaker: Malvin Gattinger<\/a> (ILLC, University of Amsterdam)<\/p>\n Date and Time: Thursday, April 9th 2026, 15:30-17:00 Venue: ILLC Seminar Room F1.15, Science Park 107 and<\/strong>\u00a0online<\/a>.<\/p>\n Title: Do you know if the road is still there? Sabotage Modal Logic with Knowledge.<\/strong><\/p>\n Abstract. <\/em>Sabotage Modal Logic (SML), originally proposed by Johan van Benthem, is concerned with a two-player game between traveller and demon played on a graph: traveller wants to get from A to B, but demon may delete edges between nodes. Formally, the traveller is modelled by a standard diamond modality whereas the demon is a dynamic modality that deletes edges. Different versions of the resulting logic have been studied in the literature.<\/p>\n In this talk I will describe ongoing work where we add a third modality: the knowledge of the traveller. The resulting language we call SML+K and it can express sentences such as “After any two deletions the traveller still knows that there is a three-step path to the goal”. Or “There is a deletion after which there still is a three-step path to the goal but the traveller will no longer know that there is such a path.”<\/p>\n We developed two semantics for SML+K, one where the knowledge is encoded by an equivalence relation between histories and one where the traveller only stores a set of graphs currently considered possible. At first sight only one of these semantics seems to have perfect-recall, but we actually aim to show that they are equivalent.<\/p>\n For both semantics I will also present a Lean formalization that can also be used as a model checker.<\/p>\n This is joint work with Sujata Ghosh and Saptarshi Sahoo (both Chennai).<\/p>\n More upcoming events:<\/p>\n [ April 9, 2026; 15:30 to 17:00. ] Speaker: Malvin Gattinger (ILLC, University of Amsterdam)<\/p>\n Date and Time: [lira-this] Venue: ILLC Seminar Room F1.15, Science Park 107 and\u00a0online.<\/p>\n Title: Do you know if the road is still there? Sabotage Modal Logic with Knowledge.<\/p>\n Abstract. Sabotage Modal Logic (SML), originally proposed by Johan van Benthem, is concerned with a two-player game between traveller and […]<\/p>\n","protected":false},"author":11,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-2706","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/pages\/2706","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/users\/11"}],"replies":[{"embeddable":true,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/comments?post=2706"}],"version-history":[{"count":17,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/pages\/2706\/revisions"}],"predecessor-version":[{"id":5164,"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/pages\/2706\/revisions\/5164"}],"wp:attachment":[{"href":"https:\/\/projects.illc.uva.nl\/lgc\/seminar\/wp-json\/wp\/v2\/media?parent=2706"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n(Please note the earlier-than-usual time.)<\/p>\n
\n","protected":false},"excerpt":{"rendered":"
\n(Please note the earlier-than-usual time.)<\/p>\n