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Quantified intuitionistic logic over metrizable spaces. (English) Zbl 1445.03007

A predicate topological space is a pair \(\langle X,D\rangle\), where \(X\) is a topological space, \(D\) is a system of domains, i.e., a function assigning a non-empty domain \(D_x\) to each point \(x\in X\) in such a way that for any \(d\in D_X=\bigcup\limits_{x\in X}D_x\), the set \(\{x\in X:d\in D_x\}\) is open in \(X\). If \(D_x\) does not depend on \(x\), then \(\langle X,D\rangle\) is a predicate topological space with a constant domain. A predicate topological model based on a predicate topological space \(\langle X,D\rangle\) is a triple \(\mathbf M=\langle X,D,V\rangle\), where \(V\) is an evaluation, i.e., a function assigning an open set \(\mathrm{Val}_{\mathbf M}(A)\) to each atomic sentence \(A\) with constants in \(D_X\). Then \(\mathrm{Val}_{\mathbf M}(A)\) is defined for each sentence \(A\) according to the interpretation of logical operations and quantifiers in the Heyting algebra of the open subsets of \(X\). A pair \(\langle\Gamma,\Delta\rangle\) of non-empty sets of sentences is called consistent iff the formula \(\bigwedge\Gamma'\to\bigvee\Delta'\) is not a theorem of the intuitionistic predicate logic QH for any finite subsets \(\Gamma'\subseteq\Gamma\), \(\Delta'\subseteq\Delta\). One says that QH is strongly complete for a predicate topological space \(\langle X,D\rangle\) iff for any consistent pair \(\langle\Gamma,\Delta\rangle\), there exists a predicate topological model \(\mathbf M\) based on \(\langle X,D\rangle\) such that \(\bigcap_{A\in\Gamma}\mathrm{Val}_{\mathbf M}(A)\setminus\bigcup_{A\in\Delta} \mathrm{Val}_{\mathbf M}(A)\not=\emptyset\). QH is strongly complete for a topological space \(X\) iff there exists a system of domains \(D\) such that QH is strongly complete for \(\langle X,D\rangle\). It is known that QH is strongly complete for the irrational line \(\mathbb P\) and the rational line \(\mathbb Q\). Each of \(\mathbb P\) and \(\mathbb Q\) is a separable zero-dimensional dense-in-itself metrizable space. The main result of the paper is Theorem 3.1: QH is strongly complete for any zero-dimensional dense-in-itself metrizable space with a constant domain of cardinality \(\le\) the space’s weight, i.e., the minimal cardinality of a basis for the space. If varying domains are allowed, then the requirement of zero-dimensionality can be removed and only countable domains can be considered. Namely, Theorem 3.3 states that for any dense-in-itself metrizable space \(X\), there is a system of countable domains \(D\) such that QH is strongly complete for \(\langle X,D\rangle\). It follows that QH is strongly complete for \(\mathbb R\) in topological semantics with varying domains although this is not the case with a constant domain.

MSC:

03B20 Subsystems of classical logic (including intuitionistic logic)
Full Text: DOI

References:

[1] AwodeyS. & KishidaK. (2008). Topology and modality: The topological intepretation of first-order modal logic. Review of Symbolic Logic, 1, 146-166. · Zbl 1204.03023
[2] DragalinA. G. (1988). Mathematical Intuitionism: Introduction to Proof Theory, trans. MendelsonE., Translations of Mathematical Monographs, Vol. 67. Providence, RI: American Mathematical Society. (Russian original: 1979.) · Zbl 0439.03041
[3] DugundjiJ. (1966). Topology. Boston: Allyn and Bacon. · Zbl 0144.21501
[4] EngelkingR. (1978). Dimension Theory. Amsterdam: North-Holland. · Zbl 0401.54029
[5] EngelkingR. (1989). General Topology. Berlin: Heldermann Verlag. · Zbl 0684.54001
[6] FourmanM. P. & ScottD. S. (1979). Sheaves and logic. In FourmanM. P., MulveyC. J., and ScottD. S., editors. Applications of Sheaves, Lecture Notes in Mathematics, Vol. 753. Berlin: Springer-Verlag, pp. 302-401. · Zbl 0415.03053
[7] GabbayD. M., ShehtmanV. B., & SkvortsovD. (2009). Quantification in Nonclassical Logic, Vol. 1. Amsterdam: Elsevier. · Zbl 1211.03002
[8] GierzG., HoffmannK. H., KeimelK., LawsonJ. D., MisloveM., & ScottD. S. (2003). Continuous Lattices and Domains. Cambridge: Cambridge University Press. · Zbl 1088.06001
[9] KremerP. (2013). Strong completeness of S4 for any dense-in-itself metric space. Review of Symbolic Logic, 6, 545-570. · Zbl 1326.03025
[10] KremerP. (2014). Quantified modal logic on the rational line. Review of Symbolic Logic, 7, 439-454. · Zbl 1329.03058
[11] KremerP. (2014). Quantified S4 in the Lebesgue measure algebra with a constant countable domain, unpublished manuscript.
[12] LandoT.First order S4 and its measure-theoretic semantics. Annals of Pure and Applied Logic, 166, 187-218. · Zbl 1369.03104
[13] McKinseyJ. C. C. (1941). A solution of the decision problem for the Lewis systems S2 and S4, with an application to topology. The Journal of Symbolic Logic, 6, 117-134. · JFM 67.0974.01
[14] McKinseyJ. C. C. & TarskiA. (1944). The algebra of topology. Annals of Mathematics, 45, 141-191. · Zbl 0060.06206
[15] MediniA. & MilovichD. (2012). The topology of ultrafilters as subspaces of 2^ω. Topology and its Applications, 159, 1318-1333. · Zbl 1241.03058
[16] MoerdijkI. (1982). Some topological spaces which are universal for intuitionistic predicate logic. Indagationes Mathematicae (Proceedings), 85, 227-235. · Zbl 0487.03033
[17] MoschovakisJ. (2018). Intuitionistic logic. In ZaltaE. N., editor. The Stanford Encyclopedia of Philosophy (Winter 2018 edition). Available at: https://plato.stanford.edu/entries/logic-intuitionistic/.
[18] MostowskiA. (1948). Proofs of nondeducibility in intuitionistic functional calculus. Journal of Symbolic Logic, 13, 204-207. · Zbl 0031.19304
[19] RasiowaH. (1951). Algebraic treatment of the functional calculi of Heyting and Lewis. Fundamenta Mathematicae, 38, 99-126. · Zbl 0044.24902
[20] RasiowaH. & SikorskiR. (1963). The Mathematics of Metamathematics. Warsaw: Państowowe Wydawnictwo Naukowe. · Zbl 0122.24311
[21] SørensenM. H. & UrzyczynP. (2006). Lectures on the Curry-Howard Isomorphism, Studies in Logic and the Foundations of Mathematics, Vol. 149. Amsterdam: Elsevier. · Zbl 1183.03004
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