## Journal of Symbolic Logic

### Constructive interpolation in hybrid logic

#### Abstract

Craig’s interpolation lemma (if $φ\rightarrowψ$ is valid, then $φ\rightarrowθ$ and $θ\rightarrowψ$ are valid, for θ a formula constructed using only primitive symbols which occur both in φ and ψ) fails for many propositional and first order modal logics. The interpolation property is often regarded as a sign of well-matched syntax and semantics. Hybrid logicians claim that modal logic is missing important syntactic machinery, namely tools for referring to worlds, and that adding such machinery solves many technical problems. The paper presents strong evidence for this claim by defining interpolation algorithms for both propositional and first order hybrid logic. These algorithms produce interpolants for the hybrid logic of every elementary class of frames satisfying the property that a frame is in the class if and only if all its point-generated subframes are in the class. In addition, on the class of all frames, the basic algorithm is conservative: on purely modal input it computes interpolants in which the hybrid syntactic machinery does not occur.

#### Article information

Source
J. Symbolic Logic, Volume 68, Issue 2 (2003), 463- 480.

Dates
First available in Project Euclid: 11 May 2003

https://projecteuclid.org/euclid.jsl/1052669059

Digital Object Identifier
doi:10.2178/jsl/1052669059

Mathematical Reviews number (MathSciNet)
MR1976586

Zentralblatt MATH identifier
1059.03020

#### Citation

Blackburn, Patrick; Marx, Maarten. Constructive interpolation in hybrid logic. J. Symbolic Logic 68 (2003), no. 2, 463-- 480. doi:10.2178/jsl/1052669059. https://projecteuclid.org/euclid.jsl/1052669059

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