Algebraically closed structures in positive logic

Pseudo Algebraically Closed Extensions

Deenability of Geometric Properties in Algebraically Closed Fields Deenability of Geometric Properties in Algebraically Closed Fields Deenability of Geometric Properties in Algebraically Closed Fields

We prove that there exists no sentence F of the language of rings with an extra binary predicat I satisfying the following property for every de nable set X C X is connected if and only if C X j F where I is interpreted by X We conjecture that the same result holds for the closed subsets of C We prove some results motivated by this conjecture

Imaginaries in algebraically closed valued fields

These notes are intended to accompany the tutorial series ‘Model theory of algebraically closed valued fields’ in the Workshop ‘An introduction to recent applications of model theory’, Cambridge March 29–April 8, 2005. They do not contain any new results, except for a slightly new method of exposition, due to Lippel, of parts of the proof of elimination of imaginaries, in Sections 8 and 9. They...

Grothendieck Homomorphisms in Algebraically Closed Valued Fields

We give a presentation of the construction of motivic integration, that is, a homomorphism between Grothendieck semigroups that are associated with a first-order theory of algebraically closed valued fields, in the fundamental work of Hrushovski and Kazhdan [12]. We limit our attention to a simple major subclass of V -minimal theories of the form ACVF S , that is, the theory of algebraically cl...

Imaginaries in pairs of algebraically closed fields

We consider the theory (ACFp)P of pairs F < K of algebraically closed fields of a given characteristic p. We exhibit a collection of additional sorts in which this theory has geometric elimination of imaginaries. The sorts are essentially of the form ∪a∈B(F )Va(K)/Ga(F ), where G, V,B are varieties over the prime field G a group scheme over B and V is a scheme over B (both with irreducible fibr...