more from M Fitting/R Mendelsohn

Single Idea 13145

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

Full Idea

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

Gist of Idea

D serial: 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