Re: Extending my question. Was: The relational model and relational

"Bernard Peek" <bap_at_shrdlu.com> wrote in message news:Mg9p99xYCBW+EwiW_at_diamond9.demon.co.uk...
> In message <7Ik5a.164$8e.17186852_at_mantis.golden.net>, Bob Badour
> <bbadour_at_golden.net> writes
>
> >> You and Date insist that cardinality can only be determined by
counting,
> >> which
> >> requires distinguishability. I have a scale that allows me to
determine
> >> the cardinality
> >> of a multiset of tuna cans by their collective weight.
> >
> >If you cannot identify the cans of tuna, how do you place them on the
scale?
>
> You pick one of them up (any one will do) and put it on the scale.

Exactly! And by picking one you have identified it.

>You
> don't need to identify which can you are choosing (given the assumption
> that all of the cans have the same weight).

Ah, but the very action of picking one can up identifies the can. It becomes the can in my hand and then the can on the scale. It becomes identified as separate and different from all other cans.

If the cans were not identifiable, you would not be able to knowingly pick one or to knowingly grasp one.

> >And before you can calculate a count from a weight, you must first count
> >identifiable cans then weigh them.
>
> No, you have to count cans. You do not have to count identifiable cans.

How do you know whether you are weighing cans if you cannot identify any? For the time the cans are on the scale, they are identifiable and are distinguishable from all other cans both on and off the scale.

If you cannot identify cans, how do you know which cans you have already counted and which cans remain to count?

By any chance, is english a second language for you? Received on Sun Feb 23 2003 - 04:30:43 CET