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Seminar

DDC - Computability Theory: Effective ringed spaces and Turing degrees of isomorphism types September 18, 2020 (09:00 AM PDT - 10:00 AM PDT)
Parent Program:
Location: MSRI: Online/Virtual
Speaker(s) Wesley Calvert (Southern Illinois University)
Description

Hilbert’s Tenth Problem was the only decision problem among his twenty-three problems. Precise mathematical theory of (in)computability and its interaction with number theory led to the negative solution of the problem. The seminar will focus on modern topics on computability-theoretic phenomena in number-theoretic and other algebraic and model-theoretic structures.

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

 

Video

Effective Ringed Spaces And Turing Degrees Of Isomorphism Types

Abstract/Media

To participate in this seminar, please register here: https://www.msri.org/seminars/25206

 

The Turing degree spectrum of a countable structure A is the set of all Turing degrees of isomorphic copies of A.  The Turing degree of the isomorphism type of A is the least degree in this spectrum, if there is a least degree.  Frequently one can prove that, for a given class K of structures (e.g., the class of fields), for any Turing degree d there is an element of K whose isomorphism type has degree d.  Frequently this result is established by finding that K has certain combinatorial properties.  Here we show that this universality property holds for various classes of ringed spaces: unions of subvarieties of a fixed variety, unions of arbitrary ringed spaces, and schemes.

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Effective Ringed Spaces And Turing Degrees Of Isomorphism Types

H.264 Video 25183_28681_8507_Effective_Ringed_Spaces_and_Turing_Degrees_of_Isomorphism_Types.mp4