<http://people.cs.uu.nl/jeroen/article/combinat/combinat.ps>
-Evaluation strategies and Normalization
+Evaluation Strategies and Normalization
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In the assignment we asked you to reduce various expressions until it wasn't possible to reduce them any further. For two of those expressions, this was impossible to do. One of them was this:
Indeed, it's provable that if there's *any* reduction path that delivers a value for a given expression, the normal-order evalutation strategy will terminate with that value.
-An expression is said to be in **normal form** when it's not possible to perform any more reductions. (EVEN INSIDE ABSTRACTS?) There's a sense in which you *can't get anything more out of* <code>ω ω</code>, but it's not in normal form because it still has the form of a redex.
+An expression is said to be in **normal form** when it's not possible to perform any more reductions (not even inside abstracts).
+There's a sense in which you *can't get anything more out of* <code>ω ω</code>, but it's not in normal form because it still has the form of a redex.
A computational system is said to be **confluent**, or to have the **Church-Rosser** or **diamond** property, if, whenever there are multiple possible evaluation paths, those that terminate always terminate in the same value. In such a system, the choice of which sub-expressions to evaluate first will only matter if some of them but not others might lead down a non-terminating path.
##[[Lists and Numbers]]##
-How to do with recursion with omega.
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-Next week: fixed point combinators