A general notion of realizability. (English) Zbl 1031.03080

Birkedal, Lars

Bull. Symb. Log. 8, No. 2, 266-282 (2002).

Summary: We present a general notion of realizability encompassing both standard Kleene-style realizability over partial combinatory algebras and Kleene-style realizability over more general structures, including all partial cartesian closed categories. We show how the general notion of realizability can be used to get models of dependent predicate logic, thus obtaining as a corollary (the known result) that the category Equ of equilogical spaces models dependent predicate logic. Moreover, we characterize when the general notion of realizability gives rise to a topos, i.e., a model of impredicative intuitionistic higher-order logic.

MSC:

03G30	Categorical logic, topoi
03C90	Nonclassical models (Boolean-valued, sheaf, etc.)

Keywords:

realizability; category theory; topos; partial combinatory algebras; dependent predicate logic; equilogical spaces