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

From: --CELKO-- <>
Date: 23 Feb 2003 08:33:28 -0800
Message-ID: <>

>> 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. <<

It is not identified; it is distinquished. If you mark it so that when you toss it back in the pile, your can find the same can again, then it is identified. If it is not marked and thrown on the pile, you might or might not pick the same can again. To be able to identify something, it must be given an identifier as one of its attribute.

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

Unh? This is like saying that I cannot buy a box of cookies, reach in and eat one unless every cookie has a serial number stamped on it and I know those serial numbers.

>> 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. <<

Again, no. The bag -- as a collection -- is distinguishable from the things in the rest of the universe by virtue of the boundary around it. I do not have to know the specific contents of the bag, only that it is a bag of cans instead of a bag of sand, or a bag of fish.

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

That is the whole point! I have not counted them! By virtue of the boundary that distinquished them from the rest of the universe, I have found the cardinality of the bag as a whole unit. Cardinality is not counting. There is no sequential process in the "weighting-and-dividing" operation that moved the cans, one at a time, from the "not-yet-counted" set to the "counted" set and assigned them an ordinal number in the process.

By any chance, is math not your best subject <G>?

As an aside, Steve Kass posted a short piece a few months back that is still driving me nuts. It had to do with computing cardinality in SQL; I got a column and a headache out of it (thank you for both, Steve). Received on Sun Feb 23 2003 - 17:33:28 CET

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