Re: Clean Object Class Design -- Circle/Ellipse

mikharakiri_at_yahoo.com (Mikito Harakiri) wrote in <bdf69bdf.0108060847.180f6d7c_at_posting.google.com>:
>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?

Not quite: as a plain set, monoid or group the integers are indeed a subtype of the reals, as a field or vector space they are not, nor are the reals a subtype of the integers. Going from plain subset to real vector space, the subtype definitions get stronger. For example, if A is a *subfield* of B, that implies that A is a *subgroup* of B which implies that A is a *subset* of B. Therefore if the reals were a subfield of the integers they would have to be a subset as well and they're not.

Regards,

Martijn Received on Mon Aug 06 2001 - 19:12:28 CEST