3 papers
math.LO2023
Elementary equivalence in positive logic via prime products
T. Moraschini, J. J. Wannenburg, K. Yamamoto
We introduce prime products as a generalization of ultraproducts for positive logic. Prime products are shown to satisfy a version of Łoś's Theorem restricted to positive formulas,…
math.LO2022
The small index property of the Fraïssé limit of finite Heyting algebras
Kentaro Yamamoto
We show that if a subgroup of the automorphism group of the Fraisse limit of finite Heyting algebras has a countable index, then it lies between the pointwise and setwise stabilize…
math.LO2021
The automorphism group of the Fraïssé limit of finite Heyting algebras
Kentaro Yamamoto
Roelcke non-precompactness, non-simplicity, and non-amenability of the automorphism group of the Fraïssé limit of finite Heyting algebras are examined among others.