{"id":3991,"global_id":"colleges.claremont.edu\/ccms?id=3991","global_id_lineage":["colleges.claremont.edu\/ccms?id=3991"],"author":"73","status":"publish","date":"2026-02-09 15:54:39","date_utc":"2026-02-09 23:54:39","modified":"2026-02-26 13:10:19","modified_utc":"2026-02-26 21:10:19","url":"https:\/\/colleges.claremont.edu\/ccms\/event\/antc-talk-achill-schurmann-university-of-rostock\/","rest_url":"https:\/\/colleges.claremont.edu\/ccms\/wp-json\/tribe\/events\/v1\/events\/3991","title":"Computing certificates for complete positivity (Achill Sch\u00fcrmann, University of Rostock)","description":"<p><span data-olk-copy-source=\"MessageBody\">A key problem in computer proofs based on solutions\u00a0<\/span>from copositive optimization, is checking whether or not a given quadratic form is completely positive or not. In this talk we describe the first known algorithm for arbitrary rational input. It is based on a suitable adaption of Voronoi&#8217;s Algorithm and the underlying theory from positive definite to copositive quadratic forms. We observe several similarities with the classical theory, but also some differences, in particular for three and more variables. A key element and currently the main bottleneck in our algorithm is an adapted shortest vector computation, asking for all nonnegative integer vectors attaining the copositive\u00a0minimum of a\u00a0given copositive quadratic form.<\/p>\n<p>(based on joint work with Valentin Dannenberg, Alexander Oertel,\u00a0Mathieu Dutour Sikiric and Frank Vallentin)<\/p>","excerpt":"","slug":"antc-talk-achill-schurmann-university-of-rostock","image":false,"all_day":false,"start_date":"2026-03-24 12:15:00","start_date_details":{"year":"2026","month":"03","day":"24","hour":"12","minutes":"15","seconds":"00"},"end_date":"2026-03-24 13:10:00","end_date_details":{"year":"2026","month":"03","day":"24","hour":"13","minutes":"10","seconds":"00"},"utc_start_date":"2026-03-24 19:15:00","utc_start_date_details":{"year":"2026","month":"03","day":"24","hour":"19","minutes":"15","seconds":"00"},"utc_end_date":"2026-03-24 20:10:00","utc_end_date_details":{"year":"2026","month":"03","day":"24","hour":"20","minutes":"10","seconds":"00"},"timezone":"America\/Los_Angeles","timezone_abbr":"PDT","cost":"","cost_details":{"currency_symbol":"","currency_code":"","currency_position":"","values":[]},"website":"","show_map":true,"show_map_link":true,"hide_from_listings":false,"sticky":false,"featured":false,"categories":[{"name":"Algebra \/ Number Theory \/ Combinatorics Seminar","slug":"antc-seminar","term_group":0,"term_taxonomy_id":13,"taxonomy":"tribe_events_cat","description":"","parent":0,"count":170,"filter":"raw","term_order":"0","id":13,"urls":{"self":"https:\/\/colleges.claremont.edu\/ccms\/wp-json\/tribe\/events\/v1\/categories\/13","collection":"https:\/\/colleges.claremont.edu\/ccms\/wp-json\/tribe\/events\/v1\/categories"}}],"tags":[],"venue":{"id":3332,"author":"73","status":"publish","date":"2023-12-14 21:05:45","date_utc":"2023-12-15 05:05:45","modified":"2023-12-14 21:05:45","modified_utc":"2023-12-15 05:05:45","url":"https:\/\/colleges.claremont.edu\/ccms\/venue\/estella-2099\/","venue":"Estella 2099","slug":"estella-2099","json_ld":{"@type":"Place","name":"Estella 2099","description":"","url":"https:\/\/colleges.claremont.edu\/ccms\/venue\/estella-2099\/","address":{"@type":"PostalAddress"},"telephone":"","sameAs":""},"show_map":true,"show_map_link":true,"global_id":"colleges.claremont.edu\/ccms?id=3332","global_id_lineage":["colleges.claremont.edu\/ccms?id=3332"]},"organizer":[{"id":426,"author":"73","status":"publish","date":"2018-08-17 08:08:12","date_utc":"2018-08-17 15:08:12","modified":"2018-08-17 08:08:12","modified_utc":"2018-08-17 15:08:12","url":"https:\/\/colleges.claremont.edu\/ccms\/organizer\/lenny-fukshansky-4\/","organizer":"Lenny Fukshansky","slug":"lenny-fukshansky-4","json_ld":{"@type":"Person","name":"Lenny Fukshansky","description":"","url":"","telephone":"","email":"","sameAs":""},"global_id":"colleges.claremont.edu\/ccms?id=426","global_id_lineage":["colleges.claremont.edu\/ccms?id=426"]},{"id":433,"author":"73","status":"publish","date":"2018-08-08 15:52:55","date_utc":"2018-08-08 22:52:55","modified":"2018-08-08 15:52:55","modified_utc":"2018-08-08 22:52:55","url":"https:\/\/colleges.claremont.edu\/ccms\/organizer\/gizem-karaali-2\/","organizer":"Gizem Karaali","slug":"gizem-karaali-2","json_ld":{"@type":"Person","name":"Gizem Karaali","description":"","url":"","telephone":"","email":"","sameAs":""},"global_id":"colleges.claremont.edu\/ccms?id=433","global_id_lineage":["colleges.claremont.edu\/ccms?id=433"]}],"custom_fields":[],"json_ld":{"@context":"http:\/\/schema.org","@type":"Event","name":"Computing certificates for complete positivity (Achill Sch\u00fcrmann, University of Rostock)","description":"&lt;p&gt;A key problem in computer proofs based on solutions\u00a0from copositive optimization, is checking whether or not a given quadratic form is completely positive or not. In this talk we describe [&hellip;]&lt;\/p&gt;\\n","url":"https:\/\/colleges.claremont.edu\/ccms\/event\/antc-talk-achill-schurmann-university-of-rostock\/","eventAttendanceMode":"https:\/\/schema.org\/OfflineEventAttendanceMode","eventStatus":"https:\/\/schema.org\/EventScheduled","startDate":"2026-03-24T12:15:00-07:00","endDate":"2026-03-24T13:10:00-07:00","location":{"@type":"Place","name":"Estella 2099","description":"","url":"https:\/\/colleges.claremont.edu\/ccms\/venue\/estella-2099\/","address":{"@type":"PostalAddress"},"telephone":"","sameAs":""},"organizer":{"@type":"Person","name":"Lenny Fukshansky","description":"","url":"","telephone":"","email":"","sameAs":""},"performer":"Organization"},"ticketed":false,"is_virtual":false,"virtual_url":null,"virtual_video_source":""}