First of all, I'm very new to Haskell (but very impressed). I remember having a lot of fun with Lisp as an undergrad, and recently started working with Scheme (and having a great time at it), and so I decided to look into Haskell. Like everyone else, I was totally impressed by the two line quicksort -- and hooked. Unfortunately(?), though, FP seems to pose a bit of a challenge from a semantic point of view. I remember being very impressed with "Dynamic Logic" (Harel et al.), and it really changed my way of thinking about programming languages. But are Kripke structures even of any relevance to Haskell and FP? Well, in order to think it through, I've been experimenting with the idea of reduction providing the basic accessibility relation. That's why I've been asking seemingly off-topic questions about lambda calculus and C-R (well- definedness). === Gregory Woodhouse gregory.woodhouse@sbcglobal.net "The whole of science is nothing more than a refinement of everyday thinking." -- Albert Einstein