Re: Objects and Relations

> This so wrong it hurts my head.
OK let's try this again...
Does it hurt your head to admit that 2 spheres having the same location (same center) should be discerned and that such discernability is impossible if location XYZ is chosen as a primary key for Sphere relation.

Imagine Sphere1 and imagine Sphere2 with the same center. Consider a Sphere relation.
If you choose Location XYZ as a pk then Sphere1 PK = Sphere2 PK therefore Sphere1 and Sphere2 are not discerned when they should be.

I hope you are putting a honest effort into this. If not let me know, so that I stop doing these efforts explaining.

> If two spheres are in different locations then they /are/ discernable
> as being unique. That's the whole point. Good grief.
Agreed. But you obviously miss the point. 2 different spheres CAN be in the same location XYZ if they have the same center. As they would have a common identity, they can not be discerned. Do you understand that XYZ can not be considered selected as pk because it would break principle of discernability? What part don't you understand? Received on Thu Feb 15 2007 - 16:35:18 CET