PP-2017-03:
Bezhanishvili, Nick and Marra, Vincenzo and McNeill, Daniel and Pedrini, Andrea
(2017)
*Tarski's theorem on intuitionistic logic, for polyhedra.*
[Pre-print]

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## Abstract

In 1938, Tarski proved that a formula is not intuitionistically valid

if, and only if, it has a counter-model in the Heyting algebra of open sets of

some topological space. In fact, Tarski showed that any Euclidean space R^n

with n > 1 suffices, as does e.g. the Cantor space. In particular, intuitionistic

logic cannot detect topological dimension in the frame of all open sets of a

Euclidean space. By contrast, we consider the lattice of open subpolyhedra

of a given compact polyhedron P of R^n, prove that it is a locally finite Heyting

subalgebra of the (non-locally-finite) algebra of all open sets of R^n, and

show that intuitionistic logic is able to capture the topological dimension of

P through the bounded-depth axiom schemata. Further, we show that intuitionistic logic is precisely the logic of formulas valid in all Heyting algebras

arising from polyhedra in this manner. Thus, our main theorem reconciles

through polyhedral geometry two classical results: topological completeness

in the style of Tarski, and Jaskowski's theorem that intuitionistic logic enjoys

the finite model property. Several questions of interest remain open. E.g.,

what is the intermediate logic of all closed triangulable manifolds?

Item Type: | Pre-print |
---|---|

Report Nr: | PP-2017-03 |

Series Name: | Prepublication (PP) Series |

Year: | 2017 |

Subjects: | Logic |

Depositing User: | Nick Bezhanishvili |

Date Deposited: | 18 Jan 2017 21:28 |

Last Modified: | 18 Jan 2017 21:31 |

URI: | https://eprints.illc.uva.nl/id/eprint/1520 |

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