More reverse mathematics of the Heine-Borel Theorem

被引:0
|
作者
Hirst, Jeffry L. [1 ]
Miller, Jessica [2 ]
机构
[1] Appalachian State Univ, Dept Math Sci, Boong, NC 28608 USA
[2] Catawba Valley Community Coll, Dept Math, 2550 US Highway 70 SE, Hickory, NC 28602 USA
来源
关键词
reverse mathematics; Heine-Borel; compact; countable closed; derived sequence; rca; wkl; aca; atr;
D O I
10.4115/jla.2012.4.6
中图分类号
B81 [逻辑学(论理学)];
学科分类号
010104 ; 010105 ;
摘要
Using the techniques of reverse mathematics, we characterize subsets X subset of [0,1] in terms of the strength of HB(X), the Heine-Borel Theorem for the subset. We introduce W(X), formalizing the notion that the Heine-Borel Theorem for X is weak, and S(X), formalizing the notion that the theorem is strong. Using these, we can prove the following three results: RCA(0) proves W(X) -> HB(X), RCA(0) proves S(X) -> (HB(X) -> WKL0), and ATR(0) proves (X) over bar exists -> (W(X) V S(X)).
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页数:10
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