Modular Sequent Systems for Modal Logic
نویسندگان
چکیده
We see cut-free sequent systems for the basic normal modal logics formed by any combination the axioms d, t,b, 4, 5. These systems are modular in the sense that each axiom has a corresponding rule and each combination of these rules is complete for the corresponding frame conditions. The systems are based on nested sequents, a natural generalisation of hypersequents. Nested sequents stay inside the modal language, as opposed to both the display calculus and labelled sequents. The completeness proof is via syntactic cut elimination.
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