{"id":"https://openalex.org/W2067699663","doi":"https://doi.org/10.1016/0168-0072(91)90053-o","title":"A decidable Ehrenfeucht theory with exactly two hyperarithmetic models","display_name":"A decidable Ehrenfeucht theory with exactly two hyperarithmetic models","publication_year":1991,"publication_date":"1991-07-01","ids":{"openalex":"https://openalex.org/W2067699663","doi":"https://doi.org/10.1016/0168-0072(91)90053-o","mag":"2067699663"},"language":"en","primary_location":{"id":"doi:10.1016/0168-0072(91)90053-o","is_oa":false,"landing_page_url":"https://doi.org/10.1016/0168-0072(91)90053-o","pdf_url":null,"source":{"id":"https://openalex.org/S172477885","display_name":"Annals of Pure and Applied Logic","issn_l":"0168-0072","issn":["0168-0072","1873-2461"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310320990","host_organization_name":"Elsevier BV","host_organization_lineage":["https://openalex.org/P4310320990"],"host_organization_lineage_names":["Elsevier BV"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Annals of Pure and Applied Logic","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/A5111373809","display_name":"Robert C. Reed","orcid":null},"institutions":[{"id":"https://openalex.org/I4210127048","display_name":"Summit School","ror":"https://ror.org/0327ybn08","country_code":"US","type":"education","lineage":["https://openalex.org/I4210127048"]}],"countries":["US"],"is_corresponding":true,"raw_author_name":"Robert C. Reed","raw_affiliation_strings":["9 Summit Avenue, Apt. 6, Brookline, MA 02146, United States"],"affiliations":[{"raw_affiliation_string":"9 Summit Avenue, Apt. 6, Brookline, MA 02146, United States","institution_ids":["https://openalex.org/I4210127048"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":1,"corresponding_author_ids":["https://openalex.org/A5111373809"],"corresponding_institution_ids":["https://openalex.org/I4210127048"],"apc_list":{"value":3390,"currency":"USD","value_usd":3390},"apc_paid":null,"fwci":0.0,"has_fulltext":false,"cited_by_count":18,"citation_normalized_percentile":{"value":0.20825373,"is_in_top_1_percent":false,"is_in_top_10_percent":false},"cited_by_percentile_year":{"min":89,"max":94},"biblio":{"volume":"53","issue":"2","first_page":"135","last_page":"168"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T12002","display_name":"Computability, Logic, AI Algorithms","score":0.996999979019165,"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/T12002","display_name":"Computability, Logic, AI Algorithms","score":0.996999979019165,"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/T11151","display_name":"Advanced Topology and Set Theory","score":0.967199981212616,"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/T11010","display_name":"Logic, Reasoning, and Knowledge","score":0.9528999924659729,"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"}}],"keywords":[{"id":"https://openalex.org/keywords/decidability","display_name":"Decidability","score":0.949859619140625},{"id":"https://openalex.org/keywords/countable-set","display_name":"Countable set","score":0.8855421543121338},{"id":"https://openalex.org/keywords/mathematics","display_name":"Mathematics","score":0.7801380157470703},{"id":"https://openalex.org/keywords/undecidable-problem","display_name":"Undecidable problem","score":0.649827778339386},{"id":"https://openalex.org/keywords/discrete-mathematics","display_name":"Discrete mathematics","score":0.5756951570510864},{"id":"https://openalex.org/keywords/model-theory","display_name":"Model theory","score":0.5299262404441833},{"id":"https://openalex.org/keywords/combinatorics","display_name":"Combinatorics","score":0.44966426491737366},{"id":"https://openalex.org/keywords/set","display_name":"Set (abstract data type)","score":0.43745219707489014},{"id":"https://openalex.org/keywords/computer-science","display_name":"Computer science","score":0.1346769630908966}],"concepts":[{"id":"https://openalex.org/C153269930","wikidata":"https://www.wikidata.org/wiki/Q430001","display_name":"Decidability","level":2,"score":0.949859619140625},{"id":"https://openalex.org/C110729354","wikidata":"https://www.wikidata.org/wiki/Q185478","display_name":"Countable set","level":2,"score":0.8855421543121338},{"id":"https://openalex.org/C33923547","wikidata":"https://www.wikidata.org/wiki/Q395","display_name":"Mathematics","level":0,"score":0.7801380157470703},{"id":"https://openalex.org/C192034797","wikidata":"https://www.wikidata.org/wiki/Q3502995","display_name":"Undecidable problem","level":3,"score":0.649827778339386},{"id":"https://openalex.org/C118615104","wikidata":"https://www.wikidata.org/wiki/Q121416","display_name":"Discrete mathematics","level":1,"score":0.5756951570510864},{"id":"https://openalex.org/C47030870","wikidata":"https://www.wikidata.org/wiki/Q467606","display_name":"Model theory","level":2,"score":0.5299262404441833},{"id":"https://openalex.org/C114614502","wikidata":"https://www.wikidata.org/wiki/Q76592","display_name":"Combinatorics","level":1,"score":0.44966426491737366},{"id":"https://openalex.org/C177264268","wikidata":"https://www.wikidata.org/wiki/Q1514741","display_name":"Set (abstract data type)","level":2,"score":0.43745219707489014},{"id":"https://openalex.org/C41008148","wikidata":"https://www.wikidata.org/wiki/Q21198","display_name":"Computer science","level":0,"score":0.1346769630908966},{"id":"https://openalex.org/C199360897","wikidata":"https://www.wikidata.org/wiki/Q9143","display_name":"Programming language","level":1,"score":0.0}],"mesh":[],"locations_count":1,"locations":[{"id":"doi:10.1016/0168-0072(91)90053-o","is_oa":false,"landing_page_url":"https://doi.org/10.1016/0168-0072(91)90053-o","pdf_url":null,"source":{"id":"https://openalex.org/S172477885","display_name":"Annals of Pure and Applied Logic","issn_l":"0168-0072","issn":["0168-0072","1873-2461"],"is_oa":false,"is_in_doaj":false,"is_core":true,"host_organization":"https://openalex.org/P4310320990","host_organization_name":"Elsevier BV","host_organization_lineage":["https://openalex.org/P4310320990"],"host_organization_lineage_names":["Elsevier BV"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Annals of Pure and Applied Logic","raw_type":"journal-article"}],"best_oa_location":null,"sustainable_development_goals":[{"display_name":"Reduced inequalities","score":0.4099999964237213,"id":"https://metadata.un.org/sdg/10"}],"awards":[],"funders":[],"has_content":{"pdf":false,"grobid_xml":false},"content_urls":null,"referenced_works_count":8,"referenced_works":["https://openalex.org/W1987148015","https://openalex.org/W1994483064","https://openalex.org/W2040037595","https://openalex.org/W2799061192","https://openalex.org/W3152223825","https://openalex.org/W4244805536","https://openalex.org/W6750047965","https://openalex.org/W6826663959"],"related_works":["https://openalex.org/W2140392112","https://openalex.org/W2021891065","https://openalex.org/W2049591942","https://openalex.org/W2101752691","https://openalex.org/W2125305054","https://openalex.org/W762790","https://openalex.org/W2067699663","https://openalex.org/W2919828861","https://openalex.org/W4288482050","https://openalex.org/W3119991094"],"abstract_inverted_index":null,"counts_by_year":[{"year":2024,"cited_by_count":1},{"year":2023,"cited_by_count":1},{"year":2022,"cited_by_count":1}],"updated_date":"2026-03-10T14:07:55.174380","created_date":"2025-10-10T00:00:00"}