A Dual-Context Sequent Calculus for S4 Modal Lambda-Term Synthesis



Document title: A Dual-Context Sequent Calculus for S4 Modal Lambda-Term Synthesis
Journal: Computación y sistemas
Database:
System number: 000560694
ISSN: 1405-5546
Authors: 1
2
1
Institutions: 1Universidad Nacional Autónoma de México, Facultad de Ciencias, México
2Universidad Nacional Autónoma de México, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, México
Year:
Season: Abr-Jun
Volumen: 26
Number: 2
Pages: 787-799
Country: México
Language: Inglés
English abstract In type-based program synthesis, the search of inhabitants in typed calculi can be seen as a process where a specification, given by a type A, is considered to be fulfilled if we can construct a λ-term M such that M : A, or more precisely if Γ ⊢ M : A holds, that is, if under some suitable assumptions Γ the term M inhabits the type A. In this paper, we tackle this inhabitation/synthesis problem for the case of modal types in the necessity fragment of the constructive logic S 4. Our approach is human-driven in the sense of the usual reasoning procedures of modern theorem provers. To this purpose we employ a so-called dual-context sequent calculus, where the sequents have two contexts, originally proposed to capture the notions of global and local truths without resorting to any formal semantics. The use of dual-contexts allows us to define a sequent calculus which, in comparison to other related systems for the same modal logic, exhibits simpler typing inference rules for the □ operator. In several cases, the task of searching for a term having subterms with modal types is reduced to the quest for a term containing only subterms typed by non modal propositions.
Keyword: Dual-context sequent calculus,
Constructive necessity,
Type inhabitation,
Modal lambda calculus,
Program synthesis
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