eprintid: 27700 rev_number: 8 eprint_status: archive userid: 19147 dir: disk0/00/02/77/00 datestamp: 2018-12-10 13:26:25 lastmod: 2021-04-02 15:58:35 status_changed: 2018-12-10 13:26:25 type: article metadata_visibility: show creators_name: Herzig, Andreas creators_name: Maffre, Faustine creators_idrefppn: 074664794 creators_idrefppn: 199221677 title: How to share knowledge by gossiping ispublished: pub subjects: subjects_INFO abstract: We provide a logical investigation of a simple case of communication in a network of agents called the gossip problem. Its classical version is: given n agents each of which has a secret - a fact not known to anybody else -, how many calls does it take to achieve shared knowledge of all secrets, i.e., to reach a state where every agent knows every secret? Several protocols achieving shared knowledge in 2(né2) calls exist and were proved to be optimal: no shorter sequence of calls exists. We generalize that problem and focus on higher-order shared knowledge: how many calls does it take to obtain that everybody knows that everybody knows all secrets? More generally, how many calls does it take to obtain shared knowledge of order k? This cannot be achieved simply by communicating facts: the agents also have to communicate higher-order knowledge of facts. We give an algorithm that works in (k+1)(né2) calls. We analyse its properties in a logic that we have investigated in previous work and that is based on the concept of observability of propositional variables by agents: Dynamic Epistemic Logic of Propositional Assignment and Observation DEL-PAO. This enables us in particular to give a formal proof of correctness of the algorithm. date: 2017-03 date_type: published publisher: IOS Press id_number: 10.3233/AIC-170723 faculty: info divisions: IRIT keywords: Gossip protocol keywords: epistemic logic keywords: shared knowledge keywords: common knowledge keywords: theory of mind keywords: dynamic epistemic logic keywords: visibility keywords: observability language: en has_fulltext: TRUE view_date_year: 2017 full_text_status: public publication: AI Communications volume: vol. 30 number: n° 1 pagerange: 1-17 refereed: TRUE issn: 0921-7126 oai_identifier: BibTeX_He2017.4 harvester_local_overwrite: subjects harvester_local_overwrite: eprintid harvester_local_overwrite: userid harvester_local_overwrite: date harvester_local_overwrite: dir harvester_local_overwrite: edition harvester_local_overwrite: publisher harvester_local_overwrite: date_type harvester_local_overwrite: language harvester_local_overwrite: volume harvester_local_overwrite: faculty harvester_local_overwrite: book_title harvester_local_overwrite: sub_title harvester_local_overwrite: site harvester_local_overwrite: divisions harvester_local_overwrite: editors_name harvester_local_overwrite: title harvester_local_overwrite: type harvester_local_overwrite: publication harvester_local_overwrite: abstract harvester_local_overwrite: place_of_pub harvester_local_overwrite: pagerange harvester_local_overwrite: creators_name harvester_local_overwrite: refereed harvester_local_overwrite: official_url harvester_local_overwrite: keywords harvester_local_overwrite: book_chapter harvester_local_overwrite: number harvester_local_overwrite: contributors_type harvester_local_overwrite: ispublished harvester_local_overwrite: issn harvester_local_overwrite: id_number harvester_local_overwrite: creators_idrefppn site: ut1 citation: Herzig, Andreas and Maffre, Faustine (2017) How to share knowledge by gossiping. AI Communications, vol. 30 (n° 1). pp. 1-17. document_url: https://publications.ut-capitole.fr/id/eprint/27700/1/herzig.pdf