HTab: a Terminating Tableaux System for Hybrid Logic

Hybrid logic is a formalism that is closely related to both modal logic and description logic. A variety of proof mechanisms for hybrid logic exist, but the only widely available implemented proof system, HyLoRes, is based on the resolution method. An alternative to resolution is the tableaux method, already widely used for both modal and description logics. Tableaux algorithms have also been developed for a number of hybrid logics, and the goal of the present work is to implement one of them. In this article we present the implementation of a terminating tableaux algorithm for the basic hybrid logic. The performance of the tableaux algorithm is compared with the performances of HyLoRes and HyLoTab (a system based on a different tableaux algorithm). HTab is implemented in the functional language Haskell, using the Glasgow Haskell Compiler (GHC). The code is released under the GNU GPL and can be downloaded from http://trac.loria.fr/projects/htab.