The unification problem in a propositional logic is to determine, given formula φ, whether there exists substitution σ such that σ(φ) logic. In case, unifier of φ. When unifiable has minimal complete sets unifiers, it either infinitary, finitary, or unitary, depending on the cardinality its unifiers. Otherwise, nullary. this paper, we prove modal $\mathbf {K}+\square \square \bot $ , formulas a...