منابع مشابه
Minimal extensions of Pi01 classes
A minimal extension of a Π1 class P is a Π 0 1 class Q such that P ⊂ Q, Q − P is infinite, and for any Π1 class R, if P ⊂ R ⊂ Q, then either R −P is finite or Q−R is finite; Q is a nontrivial minimal extension of P if in addition P and Q have the same Cantor-Bendixson derivative. We show that for any class P which has a single limit point A, and that point of degree ≤ 0′, P admits a nontrivial ...
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Let Ω be an algebraic closure of Qp and let F be a finite extension of Qp contained in Ω. Given positive integers f and e, the number of extensions K/F contained in Ω with residue degree f and ramification index e was computed by Krasner. This paper is concerned with the number I(F, f, e) of F -isomorphism classes of such extensions. We determine I(F, f, e) completely when p2 ∤ e and get partia...
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ژورنال
عنوان ژورنال: The Journal of Symbolic Logic
سال: 2020
ISSN: 0022-4812,1943-5886
DOI: 10.1017/jsl.2020.40