We define an interpretation of modal languages with polyadic operators in modal languages that use monadic operators (diamonds) only. We also define a simulation operator which associates a logic $\simL$ in the diamond language with each logic $\La$ in the language with polyadic modal connectives. We prove that this simulation operator transfers several useful properties of modal logics, such as finite/recursive axiomatizability, frame completeness and the finite model property, canonicity and first-order definability.
"Simulating polyadic modal logics by monadic ones." J. Symbolic Logic 68 (2) 419 - 462, June 2003. https://doi.org/10.2178/jsl/1052669058