G'day all. Quoting Rik van Ginneken <[EMAIL PROTECTED]>:
> It is more even subtle if one considers the rotation group. > The unit is keeping an object on its place. > The multiplication is doing rotations sequently. > Allright, one has an inverse here, but > the rule (a*b)*c = a*(b*c) doesn't occur; try it with a > banana or an apple! Wrong. Rotations do indeed form a group. In three dimensions, it's isomorphic to the unit quaternion group. I think you're thinking of unit octonions, which don't form a group because octonion multiplication is not associative in general. > Please make a distinction betwixt "monoids" and "monads". > The first is a group without an invertion. ...or a semigroup with an identity. > The latter is a construction in category theory (=abstract nonsense), Them's fighting words! Cheers, Andrew Bromage _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
