S4 and S5 are the beginning of what is now called normal modal logic.

The expansion rules depend on the particular modal logic used.

These possible worlds arise in the field of modal logic.

There are then at least three modal logics that we can develop.

This holds if a world may have more than one successor, which is true for most modal logic.

A good introduction to the varied interpretations of modal logic.

Lewis' own development of multiple modal logics is a case in point.

Van Benthem is known for his research in the area of modal logic.

This chapter and the subsequent ones are at the origin of modal logic.

He has worked also on modal logic, topology, and category theory.

In the most common semantics for modal logic, many "possible worlds" are considered.

These methods have also been extended to modal logic.

In any case, different answers to such questions yield different systems of modal logic.

These can be made precise using epistemic modal logic; see for details.

For a detailed explanation on modal logic, see here.

They may be viewed as a family of substructural or modal logics.

The semantics for modal logic are usually given like so:

Biannual international conference and book series in modal logic.

Some features of epistemic modal logic are in debate.

Some systems of modal logic meet this definition.

For example, Modal logic has undergone a major development that also modifies rhetoric.

Some of these types of logic have been called modal logics.

In modal logic, the lozenge expresses that there is "possibility."

This is necessarily true of all classical modal logics.

He also made significant contributions to modal logic.