degree of definability

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• Turing degree — Post s problem redirects here. For the other Post s problem , see Post s correspondence problem. In computer science and mathematical logic the Turing degree or degree of unsolvability of a set of natural numbers measures the level of algorithmic …   Wikipedia

• Computability theory — For the concept of computability, see Computability. Computability theory, also called recursion theory, is a branch of mathematical logic that originated in the 1930s with the study of computable functions and Turing degrees. The field has grown …   Wikipedia

• Recursion theory — Recursion theory, also called computability theory, is a branch of mathematical logic that originated in the 1930s with the study of computable functions and Turing degrees. The field has grown to include the study of generalized computability… …   Wikipedia

• Structure (mathematical logic) — In universal algebra and in model theory, a structure consists of a set along with a collection of finitary operations and relations which are defined on it. Universal algebra studies structures that generalize the algebraic structures such as… …   Wikipedia

• Pointclass — In the mathematical field of descriptive set theory, a pointclass is a collection of sets of points, where a point is ordinarily understood to be an element of some perfect Polish space. In practice, a pointclass is usually characterized by some… …   Wikipedia

• Julia Robinson — Infobox Scientist name = Julia Hall Bowman Robinson box width = imagesize = 200px caption = Julia Robinson in 1975 birth date = December 8, 1919 birth place = St. Louis, Missouri, United States death date = July 30, 1985 death place = Oakland,… …   Wikipedia

• Hyperarithmetical theory — In recursion theory, hyperarithmetic theory is a generalization of Turing computability. It has close connections with definability in second order arithmetic and with weak systems of set theory such as Kripke–Platek set theory. It is an… …   Wikipedia

• Mathematical logic — (also known as symbolic logic) is a subfield of mathematics with close connections to foundations of mathematics, theoretical computer science and philosophical logic.[1] The field includes both the mathematical study of logic and the… …   Wikipedia

• Post's theorem — In computability theory Post s theorem, named after Emil Post, describes the connection between the arithmetical hierarchy and the Turing degrees. Background The statement of Post s theorem requires several concepts relating to definability and… …   Wikipedia

• mathematics, foundations of — Scientific inquiry into the nature of mathematical theories and the scope of mathematical methods. It began with Euclid s Elements as an inquiry into the logical and philosophical basis of mathematics in essence, whether the axioms of any system… …   Universalium

• Wadge hierarchy — In descriptive set theory, Wadge degrees are levels of complexity for sets of reals and more comprehensively, subsets of any given topological space. Sets are compared by continuous reductions. The Wadge hierarchy is the structure of Wadge… …   Wikipedia