@article{oai:kyutech.repo.nii.ac.jp:00000125,
 author = {Sakamoto, Hiroshi and 坂本, 比呂志 and Hirata, Kouichi and 平田, 耕一 and Arimura, Hiroki},
 issue = {1},
 journal = {Theoretical Computer Science},
 month = {Apr},
 note = {The elementary formal system (EFS) is a kind of logic programs which directlymanipulates strings, and the learnability of the subclass called hereditary EFSs(HEFSs) has been investigated in the frameworks of the PAC-learning, query-learning, and inductive inference models. The hierarchy of HEFS is expressed byHEFS(m; k; t; r), where m, k, t and r denote the number of clauses, the occurrencesof variables in the head, the number of atoms in the body, and the arity of predi-cate symbols. The present paper deals with the learnability of HEFS in the querylearning model using equivalence queries and additional queries such as membership,predicate membership, entailment membership, and dependency queries. We showthat the class HEFS( ; k; t; r) is polynomial-time learnable with the equivalence andpredicate membership queries and the class HEFS( ; k;  ; r) with termination prop-erty is polynomial-time learnable with the equivalence, entailment membership, anddependency queries for the unbounded parameter  . A lowerbound on the numberof queries is presented. We also show that the class HEFS( ; k; t; r) is hard to learnwith the equivalence and membership queries under the cryptographic assumptions.Furthermore, the learnability of the class of unions of regular pattern languages,which is a subclass of HEFSs, is investigated. The bounded unions of regular pat-tern languages are polynomial-time predictable with membership query. However, allunbounded unions of regular pattern languages are not polynomial-time predictablewith membership queries if neither are the DNF formulas.},
 pages = {21--50},
 title = {Learning Elementary Formal Systems with Queries},
 volume = {298},
 year = {2003},
 yomi = {サカモト, ヒロシ and ヒラタ, コウイチ}
}