Goldblatt-Thomason Theorem for Probability Logic

Probability logic (PL) extends propositional logic with countably many probability operators, one for each rational number between 0 and 1.The formulas of this logic are interpreted over the class of Markov processes, i.e., structures of the form ⟨Ω,Σ,T ⟩, where ⟨Ω,Σ⟩ is a measurable space and T is a Markov kernel.The main contribution of this paper is the establishment of the Goldblatt-Thomason theorem for probability logic.As an application, we show that the class of Harsanyi type spaces is definable in PL.Moreover, we obtain some variants of the Goldblatt-Thomason theorem for specific subclasses of Markov processes.