Normal modal logic

In logic, normal modal logic is a set L of modal formulas such that L contains

• all propositional tautologies,
• Kripke's schema: ,

and L is closed under

• substitution,
• detachment rule: from A and A→B infer B,
• necessitation rule: from A infer .

The minimal normal modal logic is known as K.

This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia article. Browse Wikipedia for more information.