{"file_date_updated":"2023-02-20T07:30:20Z","isi":1,"acknowledgement":"This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 805223 ScaleML) and under the Marie Skłodowska-Curie grant agreement No. 840605 and from the Natural Sciences and Engineering Research Council of Canada grant RGPIN-2020-04178. Part of this work was done while Faith Ellen was visiting IST Austria.","project":[{"grant_number":"805223","name":"Elastic Coordination for Scalable Machine Learning","_id":"268A44D6-B435-11E9-9278-68D0E5697425","call_identifier":"H2020"},{"call_identifier":"H2020","grant_number":"840605","_id":"26A5D39A-B435-11E9-9278-68D0E5697425","name":"Coordination in constrained and natural distributed systems"}],"ddc":["000"],"intvolume":"       948","volume":948,"year":"2023","article_type":"original","citation":{"ista":"Alistarh D-A, Ellen F, Rybicki J. 2023. Wait-free approximate agreement on graphs. Theoretical Computer Science. 948(2), 113733.","chicago":"Alistarh, Dan-Adrian, Faith Ellen, and Joel Rybicki. “Wait-Free Approximate Agreement on Graphs.” <i>Theoretical Computer Science</i>. Elsevier, 2023. <a href=\"https://doi.org/10.1016/j.tcs.2023.113733\">https://doi.org/10.1016/j.tcs.2023.113733</a>.","apa":"Alistarh, D.-A., Ellen, F., &#38; Rybicki, J. (2023). Wait-free approximate agreement on graphs. <i>Theoretical Computer Science</i>. Elsevier. <a href=\"https://doi.org/10.1016/j.tcs.2023.113733\">https://doi.org/10.1016/j.tcs.2023.113733</a>","ama":"Alistarh D-A, Ellen F, Rybicki J. Wait-free approximate agreement on graphs. <i>Theoretical Computer Science</i>. 2023;948(2). doi:<a href=\"https://doi.org/10.1016/j.tcs.2023.113733\">10.1016/j.tcs.2023.113733</a>","short":"D.-A. Alistarh, F. Ellen, J. Rybicki, Theoretical Computer Science 948 (2023).","mla":"Alistarh, Dan-Adrian, et al. “Wait-Free Approximate Agreement on Graphs.” <i>Theoretical Computer Science</i>, vol. 948, no. 2, 113733, Elsevier, 2023, doi:<a href=\"https://doi.org/10.1016/j.tcs.2023.113733\">10.1016/j.tcs.2023.113733</a>.","ieee":"D.-A. Alistarh, F. Ellen, and J. Rybicki, “Wait-free approximate agreement on graphs,” <i>Theoretical Computer Science</i>, vol. 948, no. 2. Elsevier, 2023."},"ec_funded":1,"_id":"12566","article_number":"113733","language":[{"iso":"eng"}],"author":[{"orcid":"0000-0003-3650-940X","last_name":"Alistarh","first_name":"Dan-Adrian","full_name":"Alistarh, Dan-Adrian","id":"4A899BFC-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Ellen, Faith","last_name":"Ellen","first_name":"Faith"},{"orcid":"0000-0002-6432-6646","last_name":"Rybicki","first_name":"Joel","id":"334EFD2E-F248-11E8-B48F-1D18A9856A87","full_name":"Rybicki, Joel"}],"has_accepted_license":"1","publication":"Theoretical Computer Science","doi":"10.1016/j.tcs.2023.113733","external_id":{"isi":["000934262700001"]},"publication_identifier":{"issn":["0304-3975"]},"quality_controlled":"1","title":"Wait-free approximate agreement on graphs","status":"public","oa_version":"Published Version","oa":1,"user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","date_created":"2023-02-19T23:00:55Z","publisher":"Elsevier","scopus_import":"1","publication_status":"published","date_published":"2023-02-28T00:00:00Z","issue":"2","department":[{"_id":"DaAl"}],"abstract":[{"lang":"eng","text":"Approximate agreement is one of the few variants of consensus that can be solved in a wait-free manner in asynchronous systems where processes communicate by reading and writing to shared memory. In this work, we consider a natural generalisation of approximate agreement on arbitrary undirected connected graphs. Each process is given a node of the graph as input and, if non-faulty, must output a node such that\r\n– all the outputs are within distance 1 of one another, and\r\n– each output value lies on a shortest path between two input values.\r\nFrom prior work, it is known that there is no wait-free algorithm among  processes for this problem on any cycle of length , by reduction from 2-set agreement (Castañeda et al., 2018).\r\n\r\nIn this work, we investigate the solvability of this task on general graphs. We give a new, direct proof of the impossibility of approximate agreement on cycles of length , via a generalisation of Sperner's Lemma to convex polygons. We also extend the reduction from 2-set agreement to a larger class of graphs, showing that approximate agreement on these graphs is unsolvable. On the positive side, we present a wait-free algorithm for a different class of graphs, which properly contains the class of chordal graphs."}],"type":"journal_article","file":[{"content_type":"application/pdf","access_level":"open_access","creator":"dernst","file_name":"2023_TheoreticalCompScience_Alistarh.pdf","checksum":"b27c5290f2f1500c403494364ee39c9f","relation":"main_file","success":1,"file_id":"12570","file_size":602333,"date_created":"2023-02-20T07:30:20Z","date_updated":"2023-02-20T07:30:20Z"}],"day":"28","article_processing_charge":"Yes (via OA deal)","month":"02","date_updated":"2023-08-01T13:17:20Z","tmp":{"image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode"}}