WKL$\mathsf{WKL}下实值连续函数的编码$

Pub Date : 2023-07-24 DOI:10.1002/malq.202200031
Tatsuji Kawai
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引用次数: 0

摘要

在构造逆数学的背景下,我们证明了弱König引理(WKL$\mathsf{WKL}$)暗示了每个逐点连续函数f:[0,1]→ R$f:[0,1]\rightarrow\mathbb{R}$是由逆向数学意义上的代码引起的。结合WKL$\mathsf{WKL}$隐含范定理的事实,表明WKL$\mathsf{WKL}$隐含一致连续性定理:每个逐点连续函数f:[0,1]→ R$f:[0,1]\rightarrow\mathbb{R}$具有一致连续模。我们的结果是在Heyting算法中得到的,在所有有限类型中都有无量词选择公理。
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Coding of real-valued continuous functions under WKL $\mathsf {WKL}$

In the context of constructive reverse mathematics, we show that weak Kőnig's lemma ( WKL $\mathsf {WKL}$ ) implies that every pointwise continuous function f : [ 0 , 1 ] R $f : [0,1]\rightarrow \mathbb {R}$ is induced by a code in the sense of reverse mathematics. This, combined with the fact that WKL $\mathsf {WKL}$ implies the Fan theorem, shows that WKL $\mathsf {WKL}$ implies the uniform continuity theorem: every pointwise continuous function f : [ 0 , 1 ] R $f : [0,1]\rightarrow \mathbb {R}$ has a modulus of uniform continuity. Our results are obtained in Heyting arithmetic in all finite types with quantifier-free axiom of choice.

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