Constructive decidability of classical continuity

نویسنده

  • Martín Hötzel Escardó
چکیده

We show that the following instance of the principle of excluded middle holds: any function on the one-point compactification of the natural numbers with values on the natural numbers is either classically continuous or classically discontinuous. The proof doesn’t require choice and can be understood in any of the usual varieties of constructive mathematics. Classical (dis)continuity is a weakening of the notion of (dis)continuity, where the existential quantifiers are replaced by negated universal quantifiers. We also show that the classical continuity of all functions is equivalent to the negation of WLPO. We use this to relate uniform continuity and searchability of the Cantor space.

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عنوان ژورنال:
  • Mathematical Structures in Computer Science

دوره 25  شماره 

صفحات  -

تاریخ انتشار 2015