A Note on Bisimulation Quantifiers and Fixed Points over Transitive Frames
Giovanna D’Agostino, Giacomo Lenzi · Journal of Logic and Computation · 2007
We consider three basic questions regarding the extension of modal logic with a special kind of propositional quantifiers, known as bisimulation quantifiers, over arbitrary classes of frames: bisimulation invariance, uniform interpolation, and expressive power. In particular: – we discuss the relation between bisimulation invariance of bisimulation quantifiers and the semantical notion of amalgamation of the class of frames; – we consider a strong form of interpolation, uniform interpolation, and its relation with the closure under bisimulation quantifiers; – we compare bisimulation quantifiers logic with the better known extension of modal logic with extremal fixed points.