Multimodal logic

A multimodal logic is a modal logic that has more than one primitive modal operator. An early example of a multimodal logic was dynamic logic, introduced in 1976 and having a separate modal operator for every regular expression. A version of temporal logic introduced in 1977 and intended for program verification has two modalities, corresponding to dynamic logic's [A] and [A*] modalities for a single program A, understood as the whole universe taking one step forwards in time. The term "multimodal logic" itself was not introduced until 1980.