Re: Fraud Number 3: U-Gene
Date: 19 Jun 2006 05:34:58 -0700
Looking closer at your thread, I have realized I missed some of your comments...
> Sorry. R-tables are one possible representation of RELATION VALUES.
> Variables simply do not *need* "being represented". They have a name,
> a declared type, and they contain a value. Date models variables as a
> triple of exactly these three components.
First, I am aware of Date's definition and I do not quite feel confortable with it because it focuses too much on structural definition and not enough on the characteristics values extraction from domains. Neverthless, Date's is logically correct: it's a matter of perspective.
I also believe some of Date's definition can also lead to confusion..For instance, Date's definition relvar could lead to confusion with the definition of an attribute. (both have a name, a data type and may hold a value in time). If we define, attribute and relvar alike, one take the risk of confusing them...
For establishing etymological meaning, I advocate Pascal approach which rather makes a more direct binding between values, domains and operations possibles on the values. As you probably guessed, it is a matter of perpective...I consider relation on an ensemblist perspective rather than algebric perspective....
For instance, Pascal defines a data type as the combination of:
--> a name
--> set of constraints regulating *extraction* of values from a specific domain
--> set of operators applyable in specifc context Received on Mon Jun 19 2006 - 14:34:58 CEST
--> a name