New Modification of the Subformula Property for a Modal Logic
DOI:
https://doi.org/10.18778/0138-0680.2020.15Keywords:
subformula property, modal logic, sequent calculus, scope of □Abstract
A modified subformula property for the modal logic KD with the additional
axiom □ ◊(A ∨ B) ⊃ □ ◊ A ∨ □ ◊B is shown. A new modification of the notion of subformula is proposed for this purpose. This modification forms a natural extension of our former one on which modified subformula property for the modal logics K5, K5D and S4.2 has been shown ([2] and [4]). The finite model property as well as decidability for the logic follows from this.
References
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DOI: https://doi.org/10.18778/0138-0680.48.1.02
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