{"title":"Critical Relations of Crowns in Critical Times of Coronavirus Depression.","authors":"Ádám Kunos, Miklós Maróti, László Zádori","doi":"10.1007/s11083-021-09571-6","DOIUrl":"https://doi.org/10.1007/s11083-021-09571-6","url":null,"abstract":"<p><p>The critical relations are the building blocks of the relational clone of a relational structure with respect to the relational operations intersection and direct product. In this paper we describe the critical relations of crowns. As a consequence, we obtain that the subpower membership problem for any crown is polynomial-time solvable.</p>","PeriodicalId":74369,"journal":{"name":"Order (Dordrecht, Netherlands)","volume":"39 2","pages":"229-241"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11083-021-09571-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39173168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}