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Re: Example of expression bias?

From: paul c <toledobythesea_at_oohay.ac>
Date: Wed, 21 Jun 2006 00:56:09 GMT
Message-ID: <JO0mg.68558$Mn5.64421@pd7tw3no>


Tony D wrote:
> ...

>> A data type in RM = (a domain1 to draw values from) + (restrictions
>> implemented on domain1 --> domain constraint) + (operators that can be
>> defined using that data type)
>> ...

>
> This may be one definition of a data type (not quite one I'd accept, as
> we've thrashed over elsewhere), but there is nothing particular to RM
> about this.
> ...

"domain constraint" seems an uncommon term to me because we usually talk of constraints on relations. but I often puzzle over constraints, thinking that they could be as fundamental as any other notion, e.g., once one arrives at a similar conception of relations to Codd's, one could view everything that one does with them as either adding or subtracting constraints.

p Received on Tue Jun 20 2006 - 19:56:09 CDT

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