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The Σ21 theory of axioms of symmetry

Published online by Cambridge University Press:  12 March 2014

Galen Weitkamp*
Affiliation:
Department of Mathematics, Western Illinois University, Macomb, Illinois 61455

Abstract

The axiom of symmetry (A0) asserts that for every function F: ω2 → ω2 there is a pair of reals x and y in ω2 so that y is not in the countable set {(F(x))n: n< ω} coded by F(x) and x is not in the set coded by F(y). A(Γ) denotes axiom A0 with the restriction that graph(F) belongs to the pointclass Γ. In §2 we prove A(). In §3 we show A(), A() and ω2 ⊈ L are equivalent. In §4 several effective versions of A(REC) are examined.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1989

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