{"id":"https://openalex.org/W2322725250","doi":"https://doi.org/10.1109/tcomm.2016.2545655","title":"On the Complexity of Optimal Content Placement in Hierarchical Caching Networks","display_name":"On the Complexity of Optimal Content Placement in Hierarchical Caching Networks","publication_year":2016,"publication_date":"2016-03-23","ids":{"openalex":"https://openalex.org/W2322725250","doi":"https://doi.org/10.1109/tcomm.2016.2545655","mag":"2322725250"},"language":"en","primary_location":{"id":"doi:10.1109/tcomm.2016.2545655","is_oa":false,"landing_page_url":"https://doi.org/10.1109/tcomm.2016.2545655","pdf_url":null,"source":{"id":"https://openalex.org/S196647941","display_name":"IEEE Transactions on Communications","issn_l":"0090-6778","issn":["0090-6778","1558-0857"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310316002","host_organization_name":"IEEE Communications Society","host_organization_lineage":["https://openalex.org/P4310316002","https://openalex.org/P4310319808"],"host_organization_lineage_names":["IEEE Communications Society","Institute of Electrical and Electronics Engineers"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"IEEE Transactions on Communications","raw_type":"journal-article"},"type":"article","indexed_in":["crossref"],"open_access":{"is_oa":true,"oa_status":"green","oa_url":"https://zenodo.org/record/3498006","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5046120615","display_name":"Konstantinos Poularakis","orcid":"https://orcid.org/0000-0003-2570-3813"},"institutions":[{"id":"https://openalex.org/I145722265","display_name":"University of Thessaly","ror":"https://ror.org/04v4g9h31","country_code":"GR","type":"education","lineage":["https://openalex.org/I145722265"]}],"countries":["GR"],"is_corresponding":false,"raw_author_name":"Konstantinos Poularakis","raw_affiliation_strings":["Department of Electrical and Computer Engineering, University of Thessaly, Volos, Greece"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Department of Electrical and Computer Engineering, University of Thessaly, Volos, Greece","institution_ids":["https://openalex.org/I145722265"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5014892027","display_name":"Leandros Tassiulas","orcid":"https://orcid.org/0000-0003-0932-774X"},"institutions":[{"id":"https://openalex.org/I32971472","display_name":"Yale University","ror":"https://ror.org/03v76x132","country_code":"US","type":"education","lineage":["https://openalex.org/I32971472"]}],"countries":["US"],"is_corresponding":false,"raw_author_name":"Leandros Tassiulas","raw_affiliation_strings":["Department of Electrical Engineering, Institute for Network Science, Yale University, New Haven, CT, USA"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Department of Electrical Engineering, Institute for Network Science, Yale University, New Haven, CT, USA","institution_ids":["https://openalex.org/I32971472"]}]}],"institutions":[],"countries_distinct_count":2,"institutions_distinct_count":2,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":null,"apc_paid":null,"fwci":10.7619,"has_fulltext":false,"cited_by_count":66,"citation_normalized_percentile":{"value":0.9827943,"is_in_top_1_percent":false,"is_in_top_10_percent":true},"cited_by_percentile_year":{"min":94,"max":100},"biblio":{"volume":"64","issue":"5","first_page":"2092","last_page":"2103"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T11478","display_name":"Caching and Content Delivery","score":1.0,"subfield":{"id":"https://openalex.org/subfields/1705","display_name":"Computer Networks and Communications"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T11478","display_name":"Caching and Content Delivery","score":1.0,"subfield":{"id":"https://openalex.org/subfields/1705","display_name":"Computer Networks and Communications"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T11896","display_name":"Opportunistic and Delay-Tolerant Networks","score":0.9735999703407288,"subfield":{"id":"https://openalex.org/subfields/1705","display_name":"Computer Networks and Communications"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T10796","display_name":"Cooperative Communication and Network Coding","score":0.9725000262260437,"subfield":{"id":"https://openalex.org/subfields/1705","display_name":"Computer Networks and Communications"},"field":{"id":"https://openalex.org/fields/17","display_name":"Computer Science"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/computer-science","display_name":"Computer science","score":0.817848265171051},{"id":"https://openalex.org/keywords/cache","display_name":"Cache","score":0.7938019037246704},{"id":"https://openalex.org/keywords/server","display_name":"Server","score":0.7501997351646423},{"id":"https://openalex.org/keywords/hierarchy","display_name":"Hierarchy","score":0.7260340452194214},{"id":"https://openalex.org/keywords/content-delivery","display_name":"Content delivery","score":0.5850015878677368},{"id":"https://openalex.org/keywords/computer-network","display_name":"Computer network","score":0.5306975245475769},{"id":"https://openalex.org/keywords/reduction","display_name":"Reduction (mathematics)","score":0.5026185512542725},{"id":"https://openalex.org/keywords/popularity","display_name":"Popularity","score":0.497121125459671},{"id":"https://openalex.org/keywords/distributed-computing","display_name":"Distributed computing","score":0.48130905628204346},{"id":"https://openalex.org/keywords/path","display_name":"Path (computing)","score":0.43832919001579285}],"concepts":[{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.817848265171051},{"id":"https://openalex.org/C115537543","wikidata":"https://www.wikidata.org/wiki/Q165596","display_name":"Cache","level":2,"score":0.7938019037246704},{"id":"https://openalex.org/C93996380","wikidata":"https://www.wikidata.org/wiki/Q44127","display_name":"Server","level":2,"score":0.7501997351646423},{"id":"https://openalex.org/C31170391","wikidata":"https://www.wikidata.org/wiki/Q188619","display_name":"Hierarchy","level":2,"score":0.7260340452194214},{"id":"https://openalex.org/C2986847828","wikidata":"https://www.wikidata.org/wiki/Q269415","display_name":"Content delivery","level":2,"score":0.5850015878677368},{"id":"https://openalex.org/C31258907","wikidata":"https://www.wikidata.org/wiki/Q1301371","display_name":"Computer network","level":1,"score":0.5306975245475769},{"id":"https://openalex.org/C111335779","wikidata":"https://www.wikidata.org/wiki/Q3454686","display_name":"Reduction (mathematics)","level":2,"score":0.5026185512542725},{"id":"https://openalex.org/C2780586970","wikidata":"https://www.wikidata.org/wiki/Q1357284","display_name":"Popularity","level":2,"score":0.497121125459671},{"id":"https://openalex.org/C120314980","wikidata":"https://www.wikidata.org/wiki/Q180634","display_name":"Distributed computing","level":1,"score":0.48130905628204346},{"id":"https://openalex.org/C2777735758","wikidata":"https://www.wikidata.org/wiki/Q817765","display_name":"Path (computing)","level":2,"score":0.43832919001579285},{"id":"https://openalex.org/C2524010","wikidata":"https://www.wikidata.org/wiki/Q8087","display_name":"Geometry","level":1,"score":0.0},{"id":"https://openalex.org/C77805123","wikidata":"https://www.wikidata.org/wiki/Q161272","display_name":"Social psychology","level":1,"score":0.0},{"id":"https://openalex.org/C15744967","wikidata":"https://www.wikidata.org/wiki/Q9418","display_name":"Psychology","level":0,"score":0.0},{"id":"https://openalex.org/C162324750","wikidata":"https://www.wikidata.org/wiki/Q8134","display_name":"Economics","level":0,"score":0.0},{"id":"https://openalex.org/C34447519","wikidata":"https://www.wikidata.org/wiki/Q179522","display_name":"Market economy","level":1,"score":0.0},{"id":"https://openalex.org/C33923547","wikidata":"https://www.wikidata.org/wiki/Q395","display_name":"Mathematics","level":0,"score":0.0}],"mesh":[],"locations_count":3,"locations":[{"id":"doi:10.1109/tcomm.2016.2545655","is_oa":false,"landing_page_url":"https://doi.org/10.1109/tcomm.2016.2545655","pdf_url":null,"source":{"id":"https://openalex.org/S196647941","display_name":"IEEE Transactions on Communications","issn_l":"0090-6778","issn":["0090-6778","1558-0857"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310316002","host_organization_name":"IEEE Communications Society","host_organization_lineage":["https://openalex.org/P4310316002","https://openalex.org/P4310319808"],"host_organization_lineage_names":["IEEE Communications Society","Institute of Electrical and Electronics Engineers"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"IEEE Transactions on Communications","raw_type":"journal-article"},{"id":"pmh:oai:ir.lib.uth.gr:11615/78329","is_oa":false,"landing_page_url":"http://hdl.handle.net/11615/78329","pdf_url":null,"source":{"id":"https://openalex.org/S4306400243","display_name":"University of Thessaly Institutional Repository (University of Thessaly)","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I145722265","host_organization_name":"University of Thessaly","host_organization_lineage":["https://openalex.org/I145722265"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"IEEE Transactions on Communications","raw_type":"journalArticle"},{"id":"pmh:oai:zenodo.org:3498006","is_oa":true,"landing_page_url":"https://zenodo.org/record/3498006","pdf_url":null,"source":{"id":"https://openalex.org/S4306400562","display_name":"Zenodo (CERN European Organization for Nuclear Research)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I67311998","host_organization_name":"European Organization for Nuclear Research","host_organization_lineage":["https://openalex.org/I67311998"],"host_organization_lineage_names":[],"type":"repository"},"license":"other-oa","license_id":"https://openalex.org/licenses/other-oa","version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"","raw_type":"info:eu-repo/semantics/article"}],"best_oa_location":{"id":"pmh:oai:zenodo.org:3498006","is_oa":true,"landing_page_url":"https://zenodo.org/record/3498006","pdf_url":null,"source":{"id":"https://openalex.org/S4306400562","display_name":"Zenodo (CERN European Organization for Nuclear Research)","issn_l":null,"issn":null,"is_oa":true,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I67311998","host_organization_name":"European Organization for Nuclear Research","host_organization_lineage":["https://openalex.org/I67311998"],"host_organization_lineage_names":[],"type":"repository"},"license":"other-oa","license_id":"https://openalex.org/licenses/other-oa","version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"","raw_type":"info:eu-repo/semantics/article"},"sustainable_development_goals":[{"score":0.4699999988079071,"display_name":"Industry, innovation and infrastructure","id":"https://metadata.un.org/sdg/9"}],"awards":[{"id":"https://openalex.org/G3235965461","display_name":"Dynamically Reconfigurable Optical-Wireless Backhaul/Fronthaul with Cognitive Control Plane for Small Cells and Cloud-RANs","funder_award_id":"671551","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"}],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":34,"referenced_works":["https://openalex.org/W86044744","https://openalex.org/W1481341908","https://openalex.org/W1551092876","https://openalex.org/W1590025341","https://openalex.org/W1654689658","https://openalex.org/W1757790940","https://openalex.org/W1980005054","https://openalex.org/W1981730822","https://openalex.org/W1989289072","https://openalex.org/W1993553863","https://openalex.org/W1997783781","https://openalex.org/W2018682510","https://openalex.org/W2039090559","https://openalex.org/W2048124060","https://openalex.org/W2051773775","https://openalex.org/W2083766832","https://openalex.org/W2096220631","https://openalex.org/W2100135279","https://openalex.org/W2119755982","https://openalex.org/W2126860621","https://openalex.org/W2132987358","https://openalex.org/W2137697064","https://openalex.org/W2152593621","https://openalex.org/W2162508850","https://openalex.org/W2167776925","https://openalex.org/W2253934215","https://openalex.org/W2951847562","https://openalex.org/W2988480584","https://openalex.org/W6637754763","https://openalex.org/W6647622225","https://openalex.org/W6662496955","https://openalex.org/W6679418958","https://openalex.org/W6684901892","https://openalex.org/W6692125434"],"related_works":["https://openalex.org/W2368605798","https://openalex.org/W2518037665","https://openalex.org/W2348524959","https://openalex.org/W2368049389","https://openalex.org/W1967387355","https://openalex.org/W2119276484","https://openalex.org/W2158497990","https://openalex.org/W2943958348","https://openalex.org/W2962781040","https://openalex.org/W2599553145"],"abstract_inverted_index":{"The":[0],"ever":[1],"increasing":[2,164],"demand":[3,30],"for":[4,25,64,193],"content":[5,15,35,53,70,167],"is":[6,86,107,190],"straining":[7],"operators'":[8],"networks,":[9],"thereby":[10],"necessitating":[11],"development":[12],"of":[13,29,196],"alternative":[14],"delivery":[16],"mechanisms.":[17],"Distributed":[18],"caching":[19,59],"architectures":[20],"constitute":[21],"a":[22,44,127,140],"promising":[23],"solution":[24],"mitigating":[26],"the":[27,52,77,81,89,100,105,122,132,146,166,178,182,194],"effects":[28],"growth":[31],"by":[32,73,92,99],"placing":[33],"popular":[34],"files":[36,65],"in":[37,43,56,109,119,156],"proximity":[38],"to":[39,87,153],"users,":[40],"rather":[41],"than":[42,145],"central":[45],"site.":[46],"In":[47],"this":[48],"paper,":[49],"we":[50,135],"study":[51],"placement":[54],"problem":[55,106],"multiple-level":[57],"hierarchical":[58],"networks":[60],"where":[61],"user":[62],"requests":[63,96],"are":[66,124],"routed":[67],"upwards":[68],"toward":[69],"servers,":[71],"satisfied":[72],"intermediate":[74],"nodes":[75],"if":[76],"latter":[78],"have":[79],"cached":[80],"requested":[82],"files.":[83],"Our":[84,187],"goal":[85],"reduce":[88],"server":[90,157],"load":[91,158],"serving":[93],"as":[94,97,165],"many":[95],"possible":[98],"caches.":[101],"We":[102],"show":[103,151],"that":[104],"NP-Hard":[108],"its":[110],"general":[111,133],"form,":[112],"but":[113],"it":[114],"can":[115],"be":[116],"solved":[117],"optimally":[118],"polynomial-time":[120],"when":[121],"caches":[123],"installed":[125],"on":[126],"single":[128],"hierarchy":[129,184],"path.":[130],"For":[131],"case,":[134],"develop":[136],"an":[137],"algorithm":[138],"achieving":[139],"provably":[141],"better":[142],"approximation":[143],"ratio":[144],"best-known":[147],"counterparts.":[148],"Numerical":[149],"experiments":[150],"up":[152],"56%":[154],"reduction":[155],"over":[159],"existing":[160],"algorithms,":[161],"with":[162],"gains":[163],"popularity":[168],"distributions":[169],"get":[170],"steeper":[171],"and":[172,177],"more":[173],"diverse":[174],"across":[175],"nodes,":[176],"cache":[179],"capacities":[180],"at":[181],"upper":[183],"levels":[185],"increase.":[186],"evaluation":[188],"code":[189],"publicly":[191],"available":[192],"benefit":[195],"research":[197],"community.":[198]},"counts_by_year":[{"year":2026,"cited_by_count":1},{"year":2024,"cited_by_count":3},{"year":2023,"cited_by_count":3},{"year":2022,"cited_by_count":3},{"year":2021,"cited_by_count":8},{"year":2020,"cited_by_count":10},{"year":2019,"cited_by_count":13},{"year":2018,"cited_by_count":14},{"year":2017,"cited_by_count":9},{"year":2016,"cited_by_count":2}],"updated_date":"2026-08-04T08:18:43.703281","created_date":"2025-10-10T00:00:00"}