Normal modal logic
From Wikipedia, the free encyclopedia
In logic, normal modal logic is a set L of modal formulas such that L contains:
- All propositional tautologies;
- All instances of the Kripke schema:
and it is closed under:
- Detachment rule (Modus Ponens): from A and A→B infer B;
- Necessitation rule: from A infer
.
The modal logic satisfying exactly the above conditions is the most minimal normal modal logic called K. Most modal logics commonly used nowadays (in terms of having philosophical motivations), e.g. C. I. Lewis's S4 and S5, are extensions of K.
 |
This mathematical logic-related article is a stub. You can help Wikipedia by expanding it. |
