Multimethods have attracted a lot of attention in the literature over the last several years. Much of the focus has been on such questions as, how to choose the &auot;correct method" to dispatch to if no single method is most specialized for the given set of arguments; or, alternately, how to impose sufficient conditions that will prevent the problem from occurring in the first place.
The focus of this paper is different. We are interested in extending the notion of behavioral subtyping to the context of multimethods. We show that behavioral subtyping can indeed be naturally extended to deal with multiple dispatch; as an added bonus, we show that the problem of ambiguous methods disappears. We also investigate how, when reasoning about code that invokes multimethods, we can appeal to the enriched behavior provided by the specialized methods.'