{"id":3066,"date":"2025-11-27T10:13:36","date_gmt":"2025-11-27T08:13:36","guid":{"rendered":"https:\/\/mathematics.haifa.ac.il\/?p=3066"},"modified":"2025-11-27T11:04:16","modified_gmt":"2025-11-27T09:04:16","slug":"u-haifa-topology-geometry-seminar-wednesday-november-26-2025-speaker-lyne-moser-regensburg-title-modeling-%e2%88%9e-1-categories-with-segal-spaces","status":"publish","type":"post","link":"https:\/\/mathematics.haifa.ac.il\/?p=3066","title":{"rendered":"U. Haifa Topology &amp; Geometry seminar: Wednesday, November 26, 2025. Speaker: Lyne Moser (Regensburg). Title: &#8220;Modeling (\u221e, 1)-categories with Segal spaces&#8221;."},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Classically, (\u221e, 1)-categories are modeled by complete Segal spaces. However, many examples first arise as non-complete Segal spaces, which are then completed abstractly to obtain an (\u221e, 1)-category. With Nuiten, we construct a model of (\u221e, 1)-categories in which completeness is not required. In this talk, I will present the main features of this model structure and the strategy used to construct it. In particular, we use a theorem, from joint work with Guetta, Sarazola, and Verdugo, that provides general methods for building model structures. Since the fibrant objects of our new model of (\u221e, 1)-categories are the Segal spaces themselves, this framework allows us to work directly with Segal spaces without passing to their completions. As illustrations, I will explain how the usual nerve of a category provides a model for the inclusion of categories into (\u221e, 1)-categories, and how the new model allows one to compute pullbacks (or more general limits) of (\u221e, 1)-categories directly using non-complete Segal spaces.<br><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Recording:<br><a href=\"https:\/\/us02web.zoom.us\/rec\/share\/DNxKso0Zg_7NCRYGrSw9QpRxKOSgvp91bghVNb_79EeROTiQi818WiM-wgVqKLzF.rhB1rDQId6nmQqzN\">https:\/\/us02web.zoom.us\/rec\/share\/DNxKso0Zg_7NCRYGrSw9QpRxKOSgvp91bghVNb_79EeROTiQi818WiM-wgVqKLzF.rhB1rDQId6nmQqzN<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Classically, (\u221e, 1)-categories are modeled by complete Segal spaces. However, many examples first arise as non-complete Segal spaces, which are then completed abstractly to obtain an (\u221e, 1)-category. With Nuiten, we construct a model of (\u221e, 1)-categories in which completeness&#8230;<br \/><a class=\"read-more-button\" href=\"https:\/\/mathematics.haifa.ac.il\/?p=3066\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,4],"tags":[],"class_list":["post-3066","post","type-post","status-publish","format-standard","hentry","category-gt-seminar","category-seminar"],"_links":{"self":[{"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=\/wp\/v2\/posts\/3066","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3066"}],"version-history":[{"count":1,"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=\/wp\/v2\/posts\/3066\/revisions"}],"predecessor-version":[{"id":3067,"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=\/wp\/v2\/posts\/3066\/revisions\/3067"}],"wp:attachment":[{"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3066"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3066"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mathematics.haifa.ac.il\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3066"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}