University of Washington • CSE583 • D. Notkin © 2000
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Fixed-points (or fixpoints)
lThe idea of defining the semantics of lambda calculus by reducing first every expression to normal form (for which a simple mathematical denotation exists) by a sequence of contractions is attractive but, unfortunately, does not work as simply as suggested…  The problem is that, since every contraction step … removes a l, we have deduced a bit hastily that it decreases the overall number of ls.  We have neglected the possibility for a contraction step actually to add one l, or even more, while it removes another. – Meyer