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The Set of Better Quasi Orderings is ∏ 2 1
Author(s) -
Marcone Alberto
Publication year - 1995
Publication title -
mathematical logic quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.473
H-Index - 28
eISSN - 1521-3870
pISSN - 0942-5616
DOI - 10.1002/malq.19950410309
Subject(s) - mathematics , countable set , completeness (order theory) , cantor set , set (abstract data type) , continuum hypothesis , space (punctuation) , discrete mathematics , combinatorics , pure mathematics , mathematical analysis , computer science , programming language , operating system
In this paper we give a proof of the II 1 2 ‐completeness of the set of countable better quasi orderings (viewed as a subset of the Cantor space). This result was conjectured by Clote in [2] and proved by the author in his Ph.d. thesis [6] (see also [7]). Here we prove it using Simpson's definition of better quasi ordering ([15]) and as little bqo theory as possible.