Re: Clean Object Class Design -- Circle/Ellipse

mmeijeri_at_xs4all.nl (Martijn Meijering) wrote in message news:<90F3FDB73mmeijerixs4allnl_at_194.109.6.74>...
> Closure under operations is only part of the mathematical definition of
> type. A type is defined not only by an underlying set and a set of
> operations, but also by a set of axioms.
>
> Are the integers a subtype of the reals? It depends on which axioms you are
> considering. If you are looking at them as a plain set, monoid or group,
> the answer is yes. If you are looking at them as a field or a real vector
> space, the answer is no.
>
Do you mean that if we consider integers/reals as a plain set, monoid or group, then integer is a subclass of reals, and if view them as a field or a real vector space, then reals are a subclass of integers? Received on Mon Aug 06 2001 - 18:47:15 CEST