{"id":"https://openalex.org/W4281747036","doi":"https://doi.org/10.1145/3519935.3519992","title":"Combinatorics via closed orbits: number theoretic Ramanujan graphs are not unique neighbor expanders","display_name":"Combinatorics via closed orbits: number theoretic Ramanujan graphs are not unique neighbor expanders","publication_year":2022,"publication_date":"2022-06-09","ids":{"openalex":"https://openalex.org/W4281747036","doi":"https://doi.org/10.1145/3519935.3519992"},"language":"en","primary_location":{"id":"doi:10.1145/3519935.3519992","is_oa":false,"landing_page_url":"https://doi.org/10.1145/3519935.3519992","pdf_url":null,"source":null,"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Proceedings of the 54th Annual ACM SIGACT Symposium on Theory of Computing","raw_type":"proceedings-article"},"type":"article","indexed_in":["crossref"],"open_access":{"is_oa":true,"oa_status":"green","oa_url":"https://hdl.handle.net/1721.1/146442","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5088461474","display_name":"Amitay Kamber","orcid":"https://orcid.org/0000-0003-0719-2300"},"institutions":[{"id":"https://openalex.org/I241749","display_name":"University of Cambridge","ror":"https://ror.org/013meh722","country_code":"GB","type":"education","lineage":["https://openalex.org/I241749"]}],"countries":["GB"],"is_corresponding":true,"raw_author_name":"Amitay Kamber","raw_affiliation_strings":["University of Cambridge, UK"],"affiliations":[{"raw_affiliation_string":"University of Cambridge, UK","institution_ids":["https://openalex.org/I241749"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5109110331","display_name":"Tali Kaufman","orcid":null},"institutions":[{"id":"https://openalex.org/I13955877","display_name":"Bar-Ilan University","ror":"https://ror.org/03kgsv495","country_code":"IL","type":"education","lineage":["https://openalex.org/I13955877"]}],"countries":["IL"],"is_corresponding":false,"raw_author_name":"Tali Kaufman","raw_affiliation_strings":["Bar-Ilan University, Israel"],"affiliations":[{"raw_affiliation_string":"Bar-Ilan University, Israel","institution_ids":["https://openalex.org/I13955877"]}]}],"institutions":[],"countries_distinct_count":2,"institutions_distinct_count":2,"corresponding_author_ids":["https://openalex.org/A5088461474"],"corresponding_institution_ids":["https://openalex.org/I241749"],"apc_list":null,"apc_paid":null,"fwci":2.0095,"has_fulltext":false,"cited_by_count":5,"citation_normalized_percentile":{"value":0.85710269,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":95,"max":97},"biblio":{"volume":null,"issue":null,"first_page":"426","last_page":"435"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T11476","display_name":"Graph theory and applications","score":0.9998999834060669,"subfield":{"id":"https://openalex.org/subfields/2608","display_name":"Geometry and Topology"},"field":{"id":"https://openalex.org/fields/26","display_name":"Mathematics"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T11476","display_name":"Graph theory and applications","score":0.9998999834060669,"subfield":{"id":"https://openalex.org/subfields/2608","display_name":"Geometry and Topology"},"field":{"id":"https://openalex.org/fields/26","display_name":"Mathematics"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T11329","display_name":"Limits and Structures in Graph Theory","score":0.9983000159263611,"subfield":{"id":"https://openalex.org/subfields/2607","display_name":"Discrete Mathematics and Combinatorics"},"field":{"id":"https://openalex.org/fields/26","display_name":"Mathematics"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10948","display_name":"Advanced Combinatorial Mathematics","score":0.9962000250816345,"subfield":{"id":"https://openalex.org/subfields/2607","display_name":"Discrete Mathematics and Combinatorics"},"field":{"id":"https://openalex.org/fields/26","display_name":"Mathematics"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/expander-graph","display_name":"Expander graph","score":0.8671647906303406},{"id":"https://openalex.org/keywords/ramanujans-sum","display_name":"Ramanujan's sum","score":0.7831876277923584},{"id":"https://openalex.org/keywords/combinatorics","display_name":"Combinatorics","score":0.576256275177002},{"id":"https://openalex.org/keywords/vertex","display_name":"Vertex (graph theory)","score":0.5750733017921448},{"id":"https://openalex.org/keywords/lossless-compression","display_name":"Lossless compression","score":0.5468721389770508},{"id":"https://openalex.org/keywords/mathematics","display_name":"Mathematics","score":0.5115872025489807},{"id":"https://openalex.org/keywords/discrete-mathematics","display_name":"Discrete mathematics","score":0.35753333568573},{"id":"https://openalex.org/keywords/computer-science","display_name":"Computer science","score":0.3214111328125},{"id":"https://openalex.org/keywords/graph","display_name":"Graph","score":0.26047784090042114},{"id":"https://openalex.org/keywords/algorithm","display_name":"Algorithm","score":0.20006594061851501},{"id":"https://openalex.org/keywords/data-compression","display_name":"Data compression","score":0.09035545587539673}],"concepts":[{"id":"https://openalex.org/C154547637","wikidata":"https://www.wikidata.org/wiki/Q776602","display_name":"Expander graph","level":3,"score":0.8671647906303406},{"id":"https://openalex.org/C131220774","wikidata":"https://www.wikidata.org/wiki/Q1441456","display_name":"Ramanujan's sum","level":2,"score":0.7831876277923584},{"id":"https://openalex.org/C114614502","wikidata":"https://www.wikidata.org/wiki/Q76592","display_name":"Combinatorics","level":1,"score":0.576256275177002},{"id":"https://openalex.org/C80899671","wikidata":"https://www.wikidata.org/wiki/Q1304193","display_name":"Vertex (graph theory)","level":3,"score":0.5750733017921448},{"id":"https://openalex.org/C81081738","wikidata":"https://www.wikidata.org/wiki/Q55542","display_name":"Lossless compression","level":3,"score":0.5468721389770508},{"id":"https://openalex.org/C33923547","wikidata":"https://www.wikidata.org/wiki/Q395","display_name":"Mathematics","level":0,"score":0.5115872025489807},{"id":"https://openalex.org/C118615104","wikidata":"https://www.wikidata.org/wiki/Q121416","display_name":"Discrete mathematics","level":1,"score":0.35753333568573},{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.3214111328125},{"id":"https://openalex.org/C132525143","wikidata":"https://www.wikidata.org/wiki/Q141488","display_name":"Graph","level":2,"score":0.26047784090042114},{"id":"https://openalex.org/C11413529","wikidata":"https://www.wikidata.org/wiki/Q8366","display_name":"Algorithm","level":1,"score":0.20006594061851501},{"id":"https://openalex.org/C78548338","wikidata":"https://www.wikidata.org/wiki/Q2493","display_name":"Data compression","level":2,"score":0.09035545587539673}],"mesh":[],"locations_count":2,"locations":[{"id":"doi:10.1145/3519935.3519992","is_oa":false,"landing_page_url":"https://doi.org/10.1145/3519935.3519992","pdf_url":null,"source":null,"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Proceedings of the 54th Annual ACM SIGACT Symposium on Theory of Computing","raw_type":"proceedings-article"},{"id":"pmh:oai:dspace.mit.edu:1721.1/146442","is_oa":true,"landing_page_url":"https://hdl.handle.net/1721.1/146442","pdf_url":null,"source":{"id":"https://openalex.org/S4306400425","display_name":"DSpace@MIT (Massachusetts Institute of Technology)","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I63966007","host_organization_name":"Massachusetts Institute of Technology","host_organization_lineage":["https://openalex.org/I63966007"],"host_organization_lineage_names":[],"type":"repository"},"license":"cc-by-nc","license_id":"https://openalex.org/licenses/cc-by-nc","version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"ACM|Proceedings of the 54th Annual ACM SIGACT Symposium on Theory of Computing","raw_type":"http://purl.org/eprint/type/ConferencePaper"}],"best_oa_location":{"id":"pmh:oai:dspace.mit.edu:1721.1/146442","is_oa":true,"landing_page_url":"https://hdl.handle.net/1721.1/146442","pdf_url":null,"source":{"id":"https://openalex.org/S4306400425","display_name":"DSpace@MIT (Massachusetts Institute of Technology)","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I63966007","host_organization_name":"Massachusetts Institute of Technology","host_organization_lineage":["https://openalex.org/I63966007"],"host_organization_lineage_names":[],"type":"repository"},"license":"cc-by-nc","license_id":"https://openalex.org/licenses/cc-by-nc","version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"ACM|Proceedings of the 54th Annual ACM SIGACT Symposium on Theory of Computing","raw_type":"http://purl.org/eprint/type/ConferencePaper"},"sustainable_development_goals":[],"awards":[{"id":"https://openalex.org/G4956428346","display_name":null,"funder_award_id":"Horizon 2020 research and innovatio","funder_id":"https://openalex.org/F4320320300","funder_display_name":"European Commission"},{"id":"https://openalex.org/G5036817778","display_name":null,"funder_award_id":"European Union's Horizon 2020 research and innov","funder_id":"https://openalex.org/F4320320300","funder_display_name":"European Commission"},{"id":"https://openalex.org/G6737024644","display_name":null,"funder_award_id":"692854","funder_id":"https://openalex.org/F4320320300","funder_display_name":"European Commission"},{"id":"https://openalex.org/G797991369","display_name":"Equidistribution, fractal measures and arithmetic","funder_award_id":"803711","funder_id":"https://openalex.org/F4320320300","funder_display_name":"European Commission"},{"id":"https://openalex.org/G8318064016","display_name":null,"funder_award_id":"Horizon","funder_id":"https://openalex.org/F4320320300","funder_display_name":"European Commission"},{"id":"https://openalex.org/G8633428685","display_name":null,"funder_award_id":"European Union's Horizon 2020 research and innovat","funder_id":"https://openalex.org/F4320320300","funder_display_name":"European Commission"}],"funders":[{"id":"https://openalex.org/F4320320300","display_name":"European Commission","ror":"https://ror.org/00k4n6c32"},{"id":"https://openalex.org/F4320321950","display_name":"Hebrew University of Jerusalem","ror":"https://ror.org/03qxff017"}],"has_content":{"pdf":false,"grobid_xml":false},"content_urls":null,"referenced_works_count":19,"referenced_works":["https://openalex.org/W1991771574","https://openalex.org/W2006469590","https://openalex.org/W2018047324","https://openalex.org/W2028140065","https://openalex.org/W2036871172","https://openalex.org/W2043558432","https://openalex.org/W2047342855","https://openalex.org/W2057642197","https://openalex.org/W2099935635","https://openalex.org/W2142408004","https://openalex.org/W2148180254","https://openalex.org/W2154943901","https://openalex.org/W2166435158","https://openalex.org/W2169998011","https://openalex.org/W2963062359","https://openalex.org/W3044513950","https://openalex.org/W3210795511","https://openalex.org/W4235946010","https://openalex.org/W4254989727"],"related_works":["https://openalex.org/W2963265122","https://openalex.org/W2100288217","https://openalex.org/W4301822686","https://openalex.org/W2983588208","https://openalex.org/W1604770422","https://openalex.org/W2051189409","https://openalex.org/W4285276608","https://openalex.org/W2798419418","https://openalex.org/W3035192619","https://openalex.org/W3098915977"],"abstract_inverted_index":{"The":[0],"question":[1],"of":[2,33],"finding":[3],"expander":[4],"graphs":[5],"with":[6],"strong":[7,31],"vertex":[8],"expansion":[9,15,18,34,42],"properties":[10],"such":[11],"as":[12],"unique":[13],"neighbor":[14],"and":[16],"lossless":[17],"is":[19,29],"central":[20],"to":[21,26],"computer":[22],"science.":[23],"A":[24],"barrier":[25],"constructing":[27],"these":[28],"that":[30],"notions":[32],"could":[35],"not":[36],"be":[37],"proven":[38],"via":[39],"the":[40],"spectral":[41],"paradigm.":[43]},"counts_by_year":[{"year":2025,"cited_by_count":2},{"year":2024,"cited_by_count":3}],"updated_date":"2026-04-13T07:58:08.660418","created_date":"2025-10-10T00:00:00"}