modefilosofi
Modefilosofi, also known as modal logic, is a branch of formal logic that extends classical propositional and predicate logic by including modal operators. These operators express modalities, which are ways of modifying the truth values of propositions. The most common modal operators are the possibility operator (diamond) and the necessity operator (box). The diamond operator, denoted by <> or □, is used to express that a proposition is possible, while the box operator, denoted by [] or □, is used to express that a proposition is necessary.
Modal logic was first developed in the early 20th century by philosophers and logicians such as C.I.
There are many different systems of modal logic, each with its own set of axioms and rules