convex != intersection

[Roy Williams]

A convex set is one where for every pair of points in the set, the
shortest path between them is completely contained in the set.

The intersection of two convex sets is also convex by this definition.

Perhaps the question is what is meant by a "rectangle" on the
celestial sphere?

Roy

--------
Caltech Center for Advanced Computing Research
roy at cacr.caltech.edu
626 395 3670
----- Original Message ----- 
From: "Ed Shaya" <Edward.J.Shaya.1 at gsfc.nasa.gov>
To: <registry at ivoa.net>
Sent: Thursday, January 29, 2004 10:12 AM
Subject: convex != intersection


>
> Why is an intersection of coverage constraints called "convex"?
>
> The intersection of two rectangles may be another rectangle.  What
is
> convex about that?
>
> Ed
>
>