Single Idea 13144

[catalogued under 4. Formal Logic / D. Modal Logic ML / 2. Tools of Modal Logic / c. Derivation rules of ML]

Full Idea

System T reflexive rules (also for B, S4, S5): a) if σ □X then σ X b) if σ ¬◊X then σ ¬X

Gist of Idea

T reflexive: a) if σ □X then σ X b) if σ ¬◊X then σ ¬X

Source

M Fitting/R Mendelsohn (First-Order Modal Logic [1998], 2.3)

Book Reference

Fitting,M/Mendelsohn,R: 'First-Order Modal Logic' [Synthese 1998], p.52

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