منابع مشابه
Subgraphs and well-quasi-ordering
Let % be a class of graphs and let i be the subgraph or the induced subgraph relation. We call % an idea/ (with respect to I) if G I G' E % implies that G E %. In this paper, we study the ideals that are well-quasiordered by I. The following are our main results. If 5 is the subgraph relation, we characterize the well-quasi-ordered ideals in terms of excluding subgraphs. If I is the induced sub...
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In this note we prove the equivalence between the axiom of choice, the well ordering principle and Zorn’s lemma, and discuss to some extent how large fragment of ZF we need in order to prove the individual implications.
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This paper is about the bar recursion operator [9], in the context of classical realizability [6, 7]. It is a sequel to the three papers [1, 2, 10]. We use the definitions and notations of the theory of classical realizability as expounded in [5, 6, 7].1 In [1], S. Berardi, M. Bezem and T. Coquand have shown that a form of the bar recursion operator can be used, in a proof-program correspondenc...
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Assuming an inaccessible cardinal κ, there is a generic extension in which MA+ 20 = κ holds and the reals have a ∆1 well-ordering.
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Well-ordering of the Reals presents a major challenge in Set theory. Under the standard Zermelo Fraenkel Set theory (ZF) with the Axiom of Choice (ZFC), a well-ordering of the Reals is indeed possible. However the Axiom of Choice (AC) had to be introduced to the original ZF theory which is then shown equivalent to the well-ordering theorem. Despite the result however, no way has still been foun...
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ژورنال
عنوان ژورنال: Annals of Pure and Applied Logic
سال: 1987
ISSN: 0168-0072
DOI: 10.1016/0168-0072(87)90060-1