Algebras for definable families of theories
نویسندگان
چکیده
منابع مشابه
Positivstellensätze for Families of Definable Functions
We present a canonical proof of both the strict and weak Positivstellensatz for rings of differentiable and smooth functions. The construction preserves definability in expansions of the real field, and it works in definably complete expansions of real closed fields as well as for real-valued functions on Banach spaces.
متن کاملDefinable subgroups of measure algebras
We show that type-definable subgroups of measure algebras are definable.
متن کاملDefinable choice for a class of weakly o-minimal theories
Given an o-minimal structure M with a group operation, we show that for a properly convex subset U , the theory of the expanded structure M′ = (M, U) has definable Skolem functions precisely when M′ is valuational. As a corollary, we get an elementary proof that the theory of any such M′ does not satisfy definable choice. §
متن کاملInfinitely Definable Structures in Small Theories
We observe simple links between preorders, semi-groups, rings and categories (and between equivalence relations, groups, elds and groupoids), which are in nitely de nable in an arbitrary structure, and apply these observations to small structures. Recall that a structure is small if it has countably many pure n-types for each integer n. A category de ned by a pure n-type in a small structure is...
متن کاملOn Pairs of Definable Orthogonal Families
We introduce the notion of an M-family of infinite subsets of N which is implicitly contained in the work of A. R. D. Mathias. We study the structure of a pair of orthogonal hereditary families A and B, where A is analytic and B is C-measurable and an M-family.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Sibirskie Elektronnye Matematicheskie Izvestiya
سال: 2019
ISSN: 1813-3304
DOI: 10.33048/semi.2019.16.038