On Sat, 19 Jul 2008 14:47:38 +0100, Jack <jj@[EMAIL PROTECTED]
>
wrote in <news:Zfmgk.7980$CE1.120@[EMAIL PROTECTED]
> in
alt.algebra.help:
[...]
> So how about |Z ---> |N?
What about it? Do you have a function f with both of the
following properties?
(1) For each integer n, f(n) is defined.
(2) For each integer n, f(n) is a non-negative integer.
If so, then it's correct to write f : Z --> N. (I can't be
bothered with the pseudo-boldface. When writing in ASCII I
try not to use 'N' and 'Z' for anything but these sets
anyway.)
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