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[lambda.git]
/
week4.mdwn
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[[!toc]]
[[!toc]]
-#These notes return to the topic of fixed point combiantors for one more return to the topic of fixed point combinators#
-
-#Q: How do you know that every term in the untyped lambda calculus has
-a fixed point?#
+#Q: How do you know that every term in the untyped lambda calculus has a fixed point?#
A: That's easy: let `T` be an arbitrary term in the lambda calculus. If
`T` has a fixed point, then there exists some `X` such that `X <~~>
A: That's easy: let `T` be an arbitrary term in the lambda calculus. If
`T` has a fixed point, then there exists some `X` such that `X <~~>
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-171,3
+168,8
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so A 4 x is to A 3 x as hyper-exponentiation is to exponentiation...
* What *exactly* is primitive recursion?
* What *exactly* is primitive recursion?
+* I hear that `Y` delivers the *least* fixed point. Least
+ according to what ordering? How do you know it's least?
+ Is leastness important?
+
+