Re: Clean Object Class Design -- Circle/Ellipse

From: (wrong string) é Deppierraz <adz_at_acm.org>
Date: Sun, 05 Aug 2001 12:00:40 +0200
Message-ID: <3B6D1948.484AD896_at_acm.org>

Martijn Meijering a écrit :
>
> A nonempty set G combined with a binary operation + is called a commutative
> group if the following axioms hold:
>
> associativity: (a+b)+c=a+(b+c) for all a,b,c in G
> neutral element: there exists an element (denoted 0) such that a+0=0+a=0
> for all a in G

Is'nt it a+0=0+a= a ?

                 ---

> inverse: for every element a there exists an element b such that a+b=0
> commutativity: a+b=b+a for all a,b in G
 

HTH
A. Deppierraz Received on Sun Aug 05 2001 - 12:00:40 CEST