{"id":"https://openalex.org/W2031884316","doi":"https://doi.org/10.1002/scj.4690170904","title":"The emptiness problem for indexed language is exponential\u2010time complete","display_name":"The emptiness problem for indexed language is exponential\u2010time complete","publication_year":1986,"publication_date":"1986-01-01","ids":{"openalex":"https://openalex.org/W2031884316","doi":"https://doi.org/10.1002/scj.4690170904","mag":"2031884316"},"language":"en","primary_location":{"id":"doi:10.1002/scj.4690170904","is_oa":false,"landing_page_url":"https://doi.org/10.1002/scj.4690170904","pdf_url":null,"source":{"id":"https://openalex.org/S58208175","display_name":"Systems and Computers in Japan","issn_l":"0882-1666","issn":["0882-1666","1520-684X"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310320595","host_organization_name":"Wiley","host_organization_lineage":["https://openalex.org/P4310320595"],"host_organization_lineage_names":["Wiley"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Systems and Computers in Japan","raw_type":"journal-article"},"type":"article","indexed_in":["crossref"],"open_access":{"is_oa":false,"oa_status":"closed","oa_url":null,"any_repository_has_fulltext":false},"authorships":[{"author_position":"first","author":{"id":"https://openalex.org/A5079522121","display_name":"Shinichi Tanaka","orcid":"https://orcid.org/0009-0001-5757-6954"},"institutions":[{"id":"https://openalex.org/I20529979","display_name":"University of Electro-Communications","ror":"https://ror.org/02x73b849","country_code":"JP","type":"education","lineage":["https://openalex.org/I20529979"]}],"countries":["JP"],"is_corresponding":false,"raw_author_name":"Shinichi Tanaka","raw_affiliation_strings":["Faculty of Electro-Communication, The University of Electro-Communications, Chofu, Japan 182"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Faculty of Electro-Communication, The University of Electro-Communications, Chofu, Japan 182","institution_ids":["https://openalex.org/I20529979"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5110384616","display_name":"Takumi Kasai","orcid":null},"institutions":[{"id":"https://openalex.org/I20529979","display_name":"University of Electro-Communications","ror":"https://ror.org/02x73b849","country_code":"JP","type":"education","lineage":["https://openalex.org/I20529979"]}],"countries":["JP"],"is_corresponding":false,"raw_author_name":"Takumi Kasai","raw_affiliation_strings":["Faculty of Electro-Communication, The University of Electro-Communications, Chofu, Japan 182"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Faculty of Electro-Communication, The University of Electro-Communications, Chofu, Japan 182","institution_ids":["https://openalex.org/I20529979"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":1,"corresponding_author_ids":[],"corresponding_institution_ids":["https://openalex.org/I20529979"],"apc_list":null,"apc_paid":null,"fwci":0.0,"has_fulltext":false,"cited_by_count":7,"citation_normalized_percentile":{"value":0.1339553,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":94,"max":96},"biblio":{"volume":"17","issue":"9","first_page":"29","last_page":"37"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T11010","display_name":"Logic, Reasoning, and Knowledge","score":0.9995999932289124,"subfield":{"id":"https://openalex.org/subfields/1702","display_name":"Artificial Intelligence"},"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/T11010","display_name":"Logic, Reasoning, and Knowledge","score":0.9995999932289124,"subfield":{"id":"https://openalex.org/subfields/1702","display_name":"Artificial Intelligence"},"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/T11567","display_name":"semigroups and automata theory","score":0.9993000030517578,"subfield":{"id":"https://openalex.org/subfields/1703","display_name":"Computational Theory and Mathematics"},"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/T11727","display_name":"Advanced Algebra and Logic","score":0.9955000281333923,"subfield":{"id":"https://openalex.org/subfields/1703","display_name":"Computational Theory and Mathematics"},"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/emptiness","display_name":"Emptiness","score":0.8281314373016357},{"id":"https://openalex.org/keywords/context-free-language","display_name":"Context-free language","score":0.6378724575042725},{"id":"https://openalex.org/keywords/class","display_name":"Class (philosophy)","score":0.5606461763381958},{"id":"https://openalex.org/keywords/mathematics","display_name":"Mathematics","score":0.5523350238800049},{"id":"https://openalex.org/keywords/context","display_name":"Context (archaeology)","score":0.5315753221511841},{"id":"https://openalex.org/keywords/undecidable-problem","display_name":"Undecidable problem","score":0.5267750024795532},{"id":"https://openalex.org/keywords/exponential-function","display_name":"Exponential function","score":0.5196470022201538},{"id":"https://openalex.org/keywords/time-complexity","display_name":"Time complexity","score":0.46298494935035706},{"id":"https://openalex.org/keywords/computer-science","display_name":"Computer science","score":0.41304194927215576},{"id":"https://openalex.org/keywords/discrete-mathematics","display_name":"Discrete mathematics","score":0.4102063477039337},{"id":"https://openalex.org/keywords/decidability","display_name":"Decidability","score":0.3298574686050415},{"id":"https://openalex.org/keywords/artificial-intelligence","display_name":"Artificial intelligence","score":0.18841174244880676},{"id":"https://openalex.org/keywords/rule-based-machine-translation","display_name":"Rule-based machine translation","score":0.10782599449157715}],"concepts":[{"id":"https://openalex.org/C2779150620","wikidata":"https://www.wikidata.org/wiki/Q1096367","display_name":"Emptiness","level":2,"score":0.8281314373016357},{"id":"https://openalex.org/C198838072","wikidata":"https://www.wikidata.org/wiki/Q729271","display_name":"Context-free language","level":3,"score":0.6378724575042725},{"id":"https://openalex.org/C2777212361","wikidata":"https://www.wikidata.org/wiki/Q5127848","display_name":"Class (philosophy)","level":2,"score":0.5606461763381958},{"id":"https://openalex.org/C33923547","wikidata":"https://www.wikidata.org/wiki/Q395","display_name":"Mathematics","level":0,"score":0.5523350238800049},{"id":"https://openalex.org/C2779343474","wikidata":"https://www.wikidata.org/wiki/Q3109175","display_name":"Context (archaeology)","level":2,"score":0.5315753221511841},{"id":"https://openalex.org/C192034797","wikidata":"https://www.wikidata.org/wiki/Q3502995","display_name":"Undecidable problem","level":3,"score":0.5267750024795532},{"id":"https://openalex.org/C151376022","wikidata":"https://www.wikidata.org/wiki/Q168698","display_name":"Exponential function","level":2,"score":0.5196470022201538},{"id":"https://openalex.org/C311688","wikidata":"https://www.wikidata.org/wiki/Q2393193","display_name":"Time complexity","level":2,"score":0.46298494935035706},{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.41304194927215576},{"id":"https://openalex.org/C118615104","wikidata":"https://www.wikidata.org/wiki/Q121416","display_name":"Discrete mathematics","level":1,"score":0.4102063477039337},{"id":"https://openalex.org/C153269930","wikidata":"https://www.wikidata.org/wiki/Q430001","display_name":"Decidability","level":2,"score":0.3298574686050415},{"id":"https://openalex.org/C154945302","wikidata":"https://www.wikidata.org/wiki/Q11660","display_name":"Artificial intelligence","level":1,"score":0.18841174244880676},{"id":"https://openalex.org/C53893814","wikidata":"https://www.wikidata.org/wiki/Q7378909","display_name":"Rule-based machine translation","level":2,"score":0.10782599449157715},{"id":"https://openalex.org/C151730666","wikidata":"https://www.wikidata.org/wiki/Q7205","display_name":"Paleontology","level":1,"score":0.0},{"id":"https://openalex.org/C134306372","wikidata":"https://www.wikidata.org/wiki/Q7754","display_name":"Mathematical analysis","level":1,"score":0.0},{"id":"https://openalex.org/C27206212","wikidata":"https://www.wikidata.org/wiki/Q34178","display_name":"Theology","level":1,"score":0.0},{"id":"https://openalex.org/C138885662","wikidata":"https://www.wikidata.org/wiki/Q5891","display_name":"Philosophy","level":0,"score":0.0},{"id":"https://openalex.org/C86803240","wikidata":"https://www.wikidata.org/wiki/Q420","display_name":"Biology","level":0,"score":0.0}],"mesh":[],"locations_count":1,"locations":[{"id":"doi:10.1002/scj.4690170904","is_oa":false,"landing_page_url":"https://doi.org/10.1002/scj.4690170904","pdf_url":null,"source":{"id":"https://openalex.org/S58208175","display_name":"Systems and Computers in Japan","issn_l":"0882-1666","issn":["0882-1666","1520-684X"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310320595","host_organization_name":"Wiley","host_organization_lineage":["https://openalex.org/P4310320595"],"host_organization_lineage_names":["Wiley"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Systems and Computers in Japan","raw_type":"journal-article"}],"best_oa_location":null,"sustainable_development_goals":[{"score":0.5400000214576721,"display_name":"Quality Education","id":"https://metadata.un.org/sdg/4"}],"awards":[],"funders":[],"has_content":{"grobid_xml":false,"pdf":false},"content_urls":null,"referenced_works_count":3,"referenced_works":["https://openalex.org/W2003872603","https://openalex.org/W2064336391","https://openalex.org/W2064968744"],"related_works":["https://openalex.org/W2972379433","https://openalex.org/W1501430220","https://openalex.org/W2989332944","https://openalex.org/W2021891065","https://openalex.org/W2583549044","https://openalex.org/W2119045600","https://openalex.org/W2584984136","https://openalex.org/W2962928105","https://openalex.org/W2170336571","https://openalex.org/W2020140696"],"abstract_inverted_index":{"Abstract":[0],"The":[1,24,57,193],"class":[2,9,19,44,53,85,95,114,155],"of":[3,10,20,29,45,54,70,86,96,115,129,156,167],"indexed":[4,116,157,173],"languages":[5,12,22,47,88,158],"properly":[6,15],"includes":[7],"the":[8,18,34,43,52,84,94,104,113,122,127,134,138,147,150,154,160,164,168,172,180,188,201,204,211],"context\u2010free":[11,46,87],"and":[13,48,66,89,106],"is":[14,37,39,49,80,90,119,141,191,196,207,214],"included":[16],"in":[17,121,159,185],"context\u2010dependent":[21,55],"[1].":[23],"emptiness":[25,105,151,169,205],"problem":[26,28,59,128,148,152,170,181,206,213],"(the":[27,60],"determining":[30,71,130],"whether":[31,72,131],"or":[32,73,132],"not":[33,74,133],"given":[35,62],"language":[36,64],"empty)":[38],"polynomial\u2010time":[40,81],"complete":[41,82,92,111],"for":[42,51,83,93,112,153,171],"undecidable":[50],"languages.":[56,98,117],"recognition":[58,107,212],"problem,":[61],"a":[63],"L":[65,78],"word":[67],"w":[68,75],",":[69],"belongs":[76],"to":[77,149],")":[79],"polynomialspace":[91],"contextdependent":[97],"This":[99,144],"paper":[100,145],"shows":[101],"that":[102,126,179,203],"both":[103],"problems":[108],"are":[109],"exponential\u2010time":[110,142,165,189,194,208,216],"It":[118],"known":[120],"pebble":[123],"game":[124],"[2]":[125],"first":[135],"player":[136],"has":[137,177],"winning":[139],"strategy":[140],"complete.":[143,209,217],"reduces":[146],"logarithmic":[161],"space,":[162],"indicating":[163],"difficulty":[166,195],"language.":[174],"Since":[175],"Aho":[176],"shown":[178],"can":[182],"be":[183],"answered":[184],"exponential":[186],"time,":[187],"completeness":[190],"shown.":[192],"also":[197,215],"directly":[198],"indicated":[199],"from":[200],"fact":[202],"Consequently,":[210]},"counts_by_year":[{"year":2015,"cited_by_count":2}],"updated_date":"2026-05-21T06:26:12.895304","created_date":"2025-10-10T00:00:00"}