From: jim Date: Fri, 20 Feb 2015 18:26:17 +0000 (-0500) Subject: unfortunately, the infinite arithmetic question's arguments need to be flipped X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=f18d270f9c73466e1ec28afb184a0fdb3fc343af unfortunately, the infinite arithmetic question's arguments need to be flipped --- diff --git a/exercises/_assignment4.mdwn b/exercises/_assignment4.mdwn index 33c7e779..226741e1 100644 --- a/exercises/_assignment4.mdwn +++ b/exercises/_assignment4.mdwn @@ -107,10 +107,10 @@ satisfies the following constraints, for any finite natural number `n`: n ^ inf == inf leq n inf == true - (Note, though, that with some notions of infinite numbers, operations like `+` and `*` are defined in such a way that `inf + n` is different from `n + inf`, and does exceed `inf`.) + (Note, though, that with *some* notions of infinite numbers, like [[!wiki ordinal numers]], operations like `+` and `*` are defined in such a way that `inf + n` is different from `n + inf`, and does exceed `inf`.) -9. Prove that `add 1 Î¾ <~~> Î¾`, where `Î¾` is the fixed -point you found in (1). What about `add 2 Î¾ <~~> Î¾`? +9. Prove that `add Î¾ 1 <~~> Î¾`, where `Î¾` is the fixed +point you found in (1). What about `add Î¾ 2 <~~> Î¾`? Comment: a fixed point for the successor function is an object such that it is unchanged after adding 1 to it. It makes a certain amount of sense