We introduce a notion of bisimulation for contingency logic interpreted on neighbourhood structures, characterise this logic as bisimulation-invariant fragment of modal logic and of first-order logic, and compare it with existing notions in the literature.

Lecture Notes in Computer Science/Lecture Notes in Artificial Intelligence
Indian Conference on Logic and Its Applications
Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands

Bakhtiari, Z., van Ditmarsch, H., & Hansen, H. (2017). Neighbourhood contingency bisimulation. In Indian Conference on Logic and its Applications (pp. 48–63). doi:10.1007/978-3-662-54069-5_5