{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,12]],"date-time":"2026-02-12T12:24:13Z","timestamp":1770899053931,"version":"3.50.1"},"publisher-location":"California","reference-count":0,"publisher":"International Joint Conferences on Artificial Intelligence Organization","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2021,9]]},"abstract":"<jats:p>Several different notions of group knowledge have been extensively\n\n  studied in the epistemic and doxastic logic literature, including\n\n  common knowledge, general knowledge (everybody-knows) and\n\n  distributed knowledge. In this paper we study a natural notion of\n\n  group knowledge between general and distributed knowledge:\n\n  somebody-knows. While something is general knowledge if and only if\n\n  it is known by everyone, this notion holds if and only if it\n\n  is known by someone.  This is stronger than distributed\n\n  knowledge, which is the knowledge that follows from the total\n\n  knowledge in the group.  We introduce a modality for somebody-knows\n\n  in the style of standard group knowledge modalities, and study its\n\n  properties. Unlike the other mentioned group knowledge modalities,\n\n  somebody-knows is not a normal modality; in particular it lacks the conjunctive\n\n  closure property. We provide an equivalent neighbourhood semantics\n\n  for the language with a single somebody-knows modality, together\n\n  with a completeness result: the somebody-knows modalities\n\n  are completely characterised by the modal logic EMN extended with a particular\n\n  weak conjunctive closure axiom.  We also show that the\n\n  satisfiability problem for this logic is PSPACE-complete. The\n\n  neighbourhood semantics and the completeness and complexity results\n\n  also carry over to logics for so-called local reasoning\n\n  (Fagin et al. 1995) with bounded ``frames of mind'', correcting an\n\n  existing completeness result in the literature (Allen 2005).<\/jats:p>","DOI":"10.24963\/kr.2021\/1","type":"proceedings-article","created":{"date-parts":[[2021,10,11]],"date-time":"2021-10-11T16:45:56Z","timestamp":1633970756000},"page":"2-11","source":"Crossref","is-referenced-by-count":10,"title":["Somebody Knows"],"prefix":"10.24963","author":[{"given":"Thomas","family":"\u00c5gotnes","sequence":"first","affiliation":[{"name":"University of Bergen, Norway"},{"name":"Southwest University, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Y\u00ec N.","family":"W\u00e1ng","sequence":"additional","affiliation":[{"name":"Sun Yat-sen University, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"10584","event":{"name":"18th International Conference on Principles of Knowledge Representation and Reasoning {KR-2021}","theme":"Artificial Intelligence","location":"Hanoii, Vietnam","acronym":"KR-2021","number":"18","sponsor":["Artificial Intelligence Journal","Principles of Knowledge Representation and Reasoning Inc.","Sea AI Lab","Potassco Solutions","European Association for Artificial Intelligence"],"start":{"date-parts":[[2020,11,12]]},"end":{"date-parts":[[2021,11,18]]}},"container-title":["Proceedings of the Eighteenth International Conference on Principles of Knowledge Representation and Reasoning"],"original-title":[],"deposited":{"date-parts":[[2021,10,11]],"date-time":"2021-10-11T16:45:57Z","timestamp":1633970757000},"score":1,"resource":{"primary":{"URL":"https:\/\/proceedings.kr.org\/2021\/1"}},"subtitle":[],"proceedings-subject":"Artificial Intelligence Research Articles","short-title":[],"issued":{"date-parts":[[2021,9]]},"references-count":0,"URL":"https:\/\/doi.org\/10.24963\/kr.2021\/1","relation":{},"subject":[],"published":{"date-parts":[[2021,9]]}}}