X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=blobdiff_plain;f=week4.mdwn;h=e2805fb3cfb02d93e8fe3409ba41201b5f3d41cf;hp=362ad66cc5574d308df3431fb7f74529388c9419;hb=5df8ee74df25b28ea841dc3a221c16c587d5b7fc;hpb=022db6707368120d959182a319f1a299c5732c1d diff --git a/week4.mdwn b/week4.mdwn index 362ad66c..e2805fb3 100644 --- a/week4.mdwn +++ b/week4.mdwn @@ -139,7 +139,7 @@ start with the `iszero` predicate, and only produce a fresh copy of `prefact` if we are forced to. -#Q. You claimed that the Ackerman function couldn't be implemented using our primitive recursion techniques (such as the techniques that allow us to define addition and multiplication). But you haven't shown that it is possible to define the Ackerman function using full recursion.# +#Q. You claimed that the Ackermann function couldn't be implemented using our primitive recursion techniques (such as the techniques that allow us to define addition and multiplication). But you haven't shown that it is possible to define the Ackermann function using full recursion.# A. OK: @@ -171,7 +171,7 @@ so `A 4 x` is to `A 3 x` as hyper-exponentiation is to exponentiation... * 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 +* How do you know that the Ackermann function can't be computed using primitive recursion techniques? * What *exactly* is primitive recursion?