YAP (was Re: Proposal: Remove Show and Eq superclasses of Num)
twhitehead at gmail.com
Wed Nov 2 23:34:30 CET 2011
On November 2, 2011 18:00:05 Paterson, Ross wrote:
> The two concepts are similar for Int and Integer, except that signum 0 = 0
> while unit 0 = 1, but the meanings of abs and signum on other types
> generalize in a different way.
> These functions are pretty common in computer algebra systems.
> The Euclidean function is the measure function into a well-ordered set
> (the naturals) used in the proof that gcd terminates. You don't actually
> use it in the code. On the other hand you do need to be able to get a
> canonical associate.
Am I correct in understanding then that there could actually be euclidean
domains that don't have good definitions unit and associate?
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