Algorithmic problems concerning first-order definability of modal formulas on the class of all finite frames.

Alexander V. Chagrov L. A. Chagrova Algorithmic problems concerning first-order definability of modal formulas on the class of all finite frames. 421-448 1995 55 Studia Logica 3 db/journals/sLogica/sLogica55.html#ChagrovC95