Logic for Computer Science/Temporal Logic

Modal Logic
Modal logic expands propositional logic by operators for the modalities possibility and necessity. These basic modal operators are usually written $$\Box$$ (or L) for necessarily and $$\Diamond$$ (or M) for possibly. Each can be defined from the other in the following way:


 * $$\Diamond P \leftrightarrow \lnot\, \Box\, \lnot\, P.$$