[[!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 3 x is to A 2 x as exponentiation is to multiplication---
so A 4 x is to A 3 x as hyper-exponentiation is to exponentiation...
+#Q. What other questions should I be asking?#
+
+* What is it about the variant fixed-point combinators that makes
+ them compatible with a call-by-value evaluation strategy?
+
+* How do you know that the Ackerman function can't be computed
+ using primitive recursion techniques?
+
+* 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?
+
+