On the persistent difficulty of disjunction

Veldman Wim

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(2003) Philosophical dimensions of logic and science, Dordrecht, Springer.

On the persistent difficulty of disjunction

Wim Veldman

pp. 77-90

We want to show, in this paper, that, in intuitionistic analysis, the union of two closed subsets of Baire space N is not always closed, and that, more generally, the union of a closed set and a II _n⁰-set is not always II _n+1⁰. In the proof of this fact we make use of the intuitionistic Borel Hierarchy Theorem, established in (Veldman, 1981) and (Veldman, 2001a).

Publication details

DOI: 10.1007/978-94-017-2612-2_7

Full citation:

Veldman, W. (2003)., On the persistent difficulty of disjunction, in A. Rojszczak, J. Cachro & G. Kurczewski (eds.), Philosophical dimensions of logic and science, Dordrecht, Springer, pp. 77-90.

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