Syntax and Semantics
Syntax
- Propositional logic
- Modality
- □ - necessarily, e.g., □ logic_is_good
- ◊ - possibly, e.g., ◊ i_am_confused
Semantics
- Semantics of propositional logic as usual
- Reachability relation between propositional interpretations
- □ X iff X in all reachable interpretations
- ◊ X iff X in some reachable interpretation