This paper is a follow-up on previous work by the author on subtyping with (set-theoretic) union, intersection and recursive types. Previously, it was shown how types may be encoded as regular tree expressions/set constraints. This gave rise to a sound and complete decision procedure for type inclusion. The result was, however, limited to a rather speci c type language. In the work reported on here, we generalize the result and develop a general technique for deriving subtyping algorithms for

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... pe languages with union, intersection and recursive types. We present separate requirements for obtaining a subtyping algorithm which is respectively sound and complete. In this way we obtain a generic strategy for implementing the subtype relation for a broad class of very expressive type languages.