Rybakov, V.V.Terziler, M.Gencer, C.2024-07-182024-07-1820001166-3081https://doi.org/10.1080/11663081.2000.10511004https://hdl.handle.net/11411/6339We 1 study unification of formulas in modal logics and consider logics which are equivolent w.r.t. unification of formulas. A criteria is given for equivalence w.r.t. uniilcation via existence or persistent formulas. A complete syntactic description cf all formulas which are non-unifiable in wide classes of modal logics is given. Passive inference rules are considered, it is shown that in any modal logic over D4 there is a finite basis for passive rules.eninfo:eu-repo/semantics/closedAccessInference RulesModal LogicsSuperintuitionistic LogicsUnificationUnifierArticle2-s2.0-8488709105910.1080/11663081.2000.105110043773-4Q136910