Projective Unification in Bi-Intuitionistic Logic
Résumé
The bi-intuitionistic propositional calculus bi-IPC is the natural symmetric extension of the intuitionistic logic IPC. We provide both an axiomatic and semantic characterization of the consistent axiomatic extensions of bi-IPC which admit projective unification. They are exactly those which contain a theorem of the form (¬ ∼)n p → (¬ ∼)^{n+1} p, for some n ∈ N -or, equivalently, which are valid on Kripke frames of n-bounded zigzag depth, a simple order-theoretic condition. We also prove that bi-IPC does not have a unitary unification type by showing that while the formula ¬ ∼p → (¬ ∼) p is a unifiable formula in bi-IPC, it cannot have a most general unifier.
Domaines
Informatique [cs]Origine | Fichiers produits par l'(les) auteur(s) |
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