{"id":"https://openalex.org/W1489508883","doi":"https://doi.org/10.1007/3-540-16486-3_99","title":"What is a hard instance of a computational problem?","display_name":"What is a hard instance of a computational problem?","publication_year":1986,"publication_date":"1986-01-01","ids":{"openalex":"https://openalex.org/W1489508883","doi":"https://doi.org/10.1007/3-540-16486-3_99","mag":"1489508883"},"language":"en","primary_location":{"id":"doi:10.1007/3-540-16486-3_99","is_oa":false,"landing_page_url":"https://doi.org/10.1007/3-540-16486-3_99","pdf_url":null,"source":{"id":"https://openalex.org/S106296714","display_name":"Lecture notes in computer science","issn_l":"0302-9743","issn":["0302-9743","1611-3349"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310319900","host_organization_name":"Springer Science+Business Media","host_organization_lineage":["https://openalex.org/P4310319900","https://openalex.org/P4310319965"],"host_organization_lineage_names":["Springer Science+Business Media","Springer Nature"],"type":"book series"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Lecture Notes in Computer Science","raw_type":"book-chapter"},"type":"conference-paper","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/A5113600199","display_name":"Ker\u2010I Ko","orcid":null},"institutions":[{"id":"https://openalex.org/I44461941","display_name":"University of Houston","ror":"https://ror.org/048sx0r50","country_code":"US","type":"education","lineage":["https://openalex.org/I44461941"]}],"countries":["US"],"is_corresponding":false,"raw_author_name":"Ker-I Ko","raw_affiliation_strings":["Dept. of Computer Science, University of Houston, 77004, Houston, Texas, U.S.A","[Univ. of Houston]"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Dept. of Computer Science, University of Houston, 77004, Houston, Texas, U.S.A","institution_ids":["https://openalex.org/I44461941"]},{"raw_affiliation_string":"[Univ. of Houston]","institution_ids":["https://openalex.org/I44461941"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5058753686","display_name":"Pekka Orponen","orcid":"https://orcid.org/0000-0002-0417-2104"},"institutions":[{"id":"https://openalex.org/I133731052","display_name":"University of Helsinki","ror":"https://ror.org/040af2s02","country_code":"FI","type":"education","lineage":["https://openalex.org/I133731052"]}],"countries":["FI"],"is_corresponding":false,"raw_author_name":"Pekka Orponen","raw_affiliation_strings":["Dept. of Computer Science, University of Helsinki, SF-00250, Helsinki, Finland","#N##TAB##TAB##TAB##TAB# University of Helsinki#N##TAB##TAB##TAB#"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Dept. of Computer Science, University of Helsinki, SF-00250, Helsinki, Finland","institution_ids":["https://openalex.org/I133731052"]},{"raw_affiliation_string":"#N##TAB##TAB##TAB##TAB# University of Helsinki#N##TAB##TAB##TAB#","institution_ids":["https://openalex.org/I133731052"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5055009733","display_name":"Uwe Sch\u00f6ning","orcid":null},"institutions":[{"id":"https://openalex.org/I4210122282","display_name":"Praktisk-Teologiske Seminar","ror":"https://ror.org/02jv9pf54","country_code":"NO","type":"other","lineage":["https://openalex.org/I4210122282"]}],"countries":["NO"],"is_corresponding":false,"raw_author_name":"Uwe Sch\u00f6ning","raw_affiliation_strings":["EWH Rheinland-Pfalz, Seminar f\u00fcr Informatik, D-5400, Koblenz, West Germany","Seminar f\u00fcr Informatik"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"EWH Rheinland-Pfalz, Seminar f\u00fcr Informatik, D-5400, Koblenz, West Germany","institution_ids":[]},{"raw_affiliation_string":"Seminar f\u00fcr Informatik","institution_ids":["https://openalex.org/I4210122282"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5088236477","display_name":"Osamu Watanabe","orcid":"https://orcid.org/0000-0003-0284-7566"},"institutions":[{"id":"https://openalex.org/I114531698","display_name":"Tokyo Institute of Technology","ror":"https://ror.org/0112mx960","country_code":"JP","type":"education","lineage":["https://openalex.org/I114531698"]}],"countries":["JP"],"is_corresponding":false,"raw_author_name":"Osamu Watanabe","raw_affiliation_strings":["Dept. of Information Science, Tokyo Institute of Technology, Tokyo, Japan","Tokyo Inst. of Tech"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Dept. of Information Science, Tokyo Institute of Technology, Tokyo, Japan","institution_ids":["https://openalex.org/I114531698"]},{"raw_affiliation_string":"Tokyo Inst. of Tech","institution_ids":["https://openalex.org/I114531698"]}]}],"institutions":[],"countries_distinct_count":4,"institutions_distinct_count":4,"corresponding_author_ids":[],"corresponding_institution_ids":[],"apc_list":{"value":5000,"currency":"EUR","value_usd":5392},"apc_paid":null,"fwci":1.3656,"has_fulltext":false,"cited_by_count":26,"citation_normalized_percentile":{"value":0.75239923,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":89,"max":96},"biblio":{"volume":null,"issue":null,"first_page":"197","last_page":"217"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T10720","display_name":"Complexity and Algorithms in Graphs","score":0.9991000294685364,"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"}},"topics":[{"id":"https://openalex.org/T10720","display_name":"Complexity and Algorithms in Graphs","score":0.9991000294685364,"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/T11567","display_name":"semigroups and automata theory","score":0.9980999827384949,"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/T12002","display_name":"Computability, Logic, AI Algorithms","score":0.9970999956130981,"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/computer-science","display_name":"Computer science","score":0.7846046090126038},{"id":"https://openalex.org/keywords/computational-complexity-theory","display_name":"Computational complexity theory","score":0.5903945565223694},{"id":"https://openalex.org/keywords/time-complexity","display_name":"Time complexity","score":0.5278701186180115},{"id":"https://openalex.org/keywords/theoretical-computer-science","display_name":"Theoretical computer science","score":0.49308106303215027},{"id":"https://openalex.org/keywords/exptime","display_name":"EXPTIME","score":0.47444355487823486},{"id":"https://openalex.org/keywords/table","display_name":"Table (database)","score":0.4370642900466919},{"id":"https://openalex.org/keywords/algorithm","display_name":"Algorithm","score":0.4279761016368866},{"id":"https://openalex.org/keywords/data-mining","display_name":"Data mining","score":0.0970660150051117},{"id":"https://openalex.org/keywords/pspace","display_name":"PSPACE","score":0.09395062923431396}],"concepts":[{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.7846046090126038},{"id":"https://openalex.org/C179799912","wikidata":"https://www.wikidata.org/wiki/Q205084","display_name":"Computational complexity theory","level":2,"score":0.5903945565223694},{"id":"https://openalex.org/C311688","wikidata":"https://www.wikidata.org/wiki/Q2393193","display_name":"Time complexity","level":2,"score":0.5278701186180115},{"id":"https://openalex.org/C80444323","wikidata":"https://www.wikidata.org/wiki/Q2878974","display_name":"Theoretical computer science","level":1,"score":0.49308106303215027},{"id":"https://openalex.org/C56049555","wikidata":"https://www.wikidata.org/wiki/Q1276570","display_name":"EXPTIME","level":4,"score":0.47444355487823486},{"id":"https://openalex.org/C45235069","wikidata":"https://www.wikidata.org/wiki/Q278425","display_name":"Table (database)","level":2,"score":0.4370642900466919},{"id":"https://openalex.org/C11413529","wikidata":"https://www.wikidata.org/wiki/Q8366","display_name":"Algorithm","level":1,"score":0.4279761016368866},{"id":"https://openalex.org/C124101348","wikidata":"https://www.wikidata.org/wiki/Q172491","display_name":"Data mining","level":1,"score":0.0970660150051117},{"id":"https://openalex.org/C197685441","wikidata":"https://www.wikidata.org/wiki/Q500716","display_name":"PSPACE","level":3,"score":0.09395062923431396}],"mesh":[],"locations_count":2,"locations":[{"id":"doi:10.1007/3-540-16486-3_99","is_oa":false,"landing_page_url":"https://doi.org/10.1007/3-540-16486-3_99","pdf_url":null,"source":{"id":"https://openalex.org/S106296714","display_name":"Lecture notes in computer science","issn_l":"0302-9743","issn":["0302-9743","1611-3349"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310319900","host_organization_name":"Springer Science+Business Media","host_organization_lineage":["https://openalex.org/P4310319900","https://openalex.org/P4310319965"],"host_organization_lineage_names":["Springer Science+Business Media","Springer Nature"],"type":"book series"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Lecture Notes in Computer Science","raw_type":"book-chapter"},{"id":"pmh:oai:t2r2.star.titech.ac.jp:50030832","is_oa":false,"landing_page_url":"http://t2r2.star.titech.ac.jp/cgi-bin/publicationinfo.cgi?q_publication_content_number=CTT100555873","pdf_url":null,"source":{"id":"https://openalex.org/S4377196385","display_name":"Tokyo Tech Research Repository (Tokyo Institute of Technology)","issn_l":null,"issn":null,"is_oa":false,"is_in_doaj":false,"is_core":false,"host_organization":"https://openalex.org/I114531698","host_organization_name":"Tokyo Institute of Technology","host_organization_lineage":["https://openalex.org/I114531698"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":"","raw_type":"Conference Paper"}],"best_oa_location":null,"sustainable_development_goals":[{"score":0.800000011920929,"display_name":"Peace, Justice and strong institutions","id":"https://metadata.un.org/sdg/16"}],"awards":[],"funders":[],"has_content":{"pdf":false,"grobid_xml":false},"content_urls":null,"referenced_works_count":14,"referenced_works":["https://openalex.org/W214738142","https://openalex.org/W1535429997","https://openalex.org/W1964186004","https://openalex.org/W1970089350","https://openalex.org/W1981282181","https://openalex.org/W1998915384","https://openalex.org/W2005097301","https://openalex.org/W2069348040","https://openalex.org/W2080325829","https://openalex.org/W2082894772","https://openalex.org/W2092583861","https://openalex.org/W2095229434","https://openalex.org/W2128322939","https://openalex.org/W2159841662"],"related_works":["https://openalex.org/W2948670949","https://openalex.org/W4288047943","https://openalex.org/W80762624","https://openalex.org/W1554599886","https://openalex.org/W1594368577","https://openalex.org/W1797990060","https://openalex.org/W4232484699","https://openalex.org/W2473636215","https://openalex.org/W961142965","https://openalex.org/W2327776271"],"abstract_inverted_index":null,"counts_by_year":[{"year":2025,"cited_by_count":1},{"year":2020,"cited_by_count":2},{"year":2019,"cited_by_count":1},{"year":2018,"cited_by_count":1},{"year":2012,"cited_by_count":1}],"updated_date":"2026-08-01T09:00:35.917206","created_date":"2025-10-10T00:00:00"}
