This paper investigates the evaluation method of decision procedures for multi-modal logic proposed by Giunchiglia and Sebastiani as an adaptation from the evaluation method of Mitchell et al of decision procedures for propositional logic. We compare three dif ferent theorem proving approaches, namely the Davis-Putnam-based procedure KSAT, the tableaux-based system KTUS and a transla tion approach combined with first-order resolu tion. Our results do not support the claims of Giunchiglia and

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... astiani concerning the com putational superiority of KSAT over KRIS, and an easy-hard-easy pattern for randomly gener ated modal formulae.