Re: On Formal IS-A definition
Date: Wed, 5 May 2010 12:41:58 -0700 (PDT)
Message-ID: <7f2a7da8-4986-4deb-ad1d-ca0431f76b8c_at_l28g2000yqd.googlegroups.com>
On 4 mei, 22:13, Tegiri Nenashi <tegirinena..._at_gmail.com> wrote:
> On May 3, 5:04 pm, paul c <toledobythe..._at_oohay.ac> wrote:
>
> > ... and never bring up,
> > say, just what the Information Principle really means.
>
> ..."the entire information content of the database is represented in
> one and only one way. Namely as explicit values in column positions
> (attributes) and rows in relations (tuples)."?
>
> It is obsolete.
How can it be ? It precisely the IP that allows the Relational Algebra to be a sufficient foundation for relational data manipulation. If other structures besides relations were admitted, relation algebra would no longer suffice.
> Presumably arithmetic principle would prevent some
> from reinventing roman numerals:-)
Roman numerals are just another possible representation for numbers. They don't prevent the numbers, represented that way, from being used in arithmetic. Not in the same sense that relation algebra prevents graph databases because relation algebra does not understand graphs. Received on Wed May 05 2010 - 21:41:58 CEST