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Main Authors: Köpp, Nils, Petrakis, Iosif
Format: Preprint
Published: 2022
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Online Access:https://arxiv.org/abs/2210.05491
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author Köpp, Nils
Petrakis, Iosif
author_facet Köpp, Nils
Petrakis, Iosif
contents We incorporate strong negation in the theory of computable functionals TCF, a common extension of Plotkin's PCF and Gödel's system $\mathbf{T}$, by defining simultaneously strong negation $A^{\mathbf{N}}$ of a formula $A$ and strong negation $P^{\mathbf{N}}$ of a predicate $P$ in TCF. As a special case of the latter, we get strong negation of an inductive and a coinductive predicate of TCF. We prove appropriate versions of the Ex falso quodlibet and of double negation elimination for strong negation in TCF. We introduce the so-called tight formulas of TCF i.e., formulas implied by the weak negation of their strong negation, and the relative tight formulas. We present various case-studies and examples, which reveal the naturality of our definition of strong negation in TCF and justify the use of TCF as a formal system for a large part of Bishop-style constructive mathematics.
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publishDate 2022
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spellingShingle Strong negation in the theory of computable functionals TCF
Köpp, Nils
Petrakis, Iosif
Logic
Logic in Computer Science
We incorporate strong negation in the theory of computable functionals TCF, a common extension of Plotkin's PCF and Gödel's system $\mathbf{T}$, by defining simultaneously strong negation $A^{\mathbf{N}}$ of a formula $A$ and strong negation $P^{\mathbf{N}}$ of a predicate $P$ in TCF. As a special case of the latter, we get strong negation of an inductive and a coinductive predicate of TCF. We prove appropriate versions of the Ex falso quodlibet and of double negation elimination for strong negation in TCF. We introduce the so-called tight formulas of TCF i.e., formulas implied by the weak negation of their strong negation, and the relative tight formulas. We present various case-studies and examples, which reveal the naturality of our definition of strong negation in TCF and justify the use of TCF as a formal system for a large part of Bishop-style constructive mathematics.
title Strong negation in the theory of computable functionals TCF
topic Logic
Logic in Computer Science
url https://arxiv.org/abs/2210.05491