2014/08/18 by Eric Faber, Faber, Eric, Jaap van Oosten +1
Engineering · #Advanced Numerical Analysis Techniques #FOS: Mathematics #Logic (math.LO)
paper · pdf · doi:10.48550/arxiv.1408.3984
openalex publication_date 2014/08/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Geometric morphisms between realizability toposes are studied in terms of morphisms between partial combinatory algebras (pcas). The morphisms inducing geometric morphisms (the \em computationally dense\/ ones) are seen to be the ones whose `lifts' to a kind of completion have right adjoints. We characterize topos inclusions corresponding to a general form of relative computability. We characterize pcas whose realizability topos admits a geometric morphism to the effective topos.