|Covariant-Contravariant Refinement Modal Logic|
Huili Xing, Zhaohui Zhu and Jinjin Zhang
The notion of covariant-contravariant refinement (CC-refinement, for short)
is a generalization of the notions of bisimulation and refinement. This paper
introduces CC-refinement modal logic (CCRML) obtained from the modal system
K by adding CC-refinement quantifiers, and provides a sound and complete
axiom system for CCRML.