Re: Representing Student Activity Score

From: Alan <not.me_at_uhuh.rcn.com>
Date: Sat, 24 Jul 2004 01:26:28 GMT
Message-ID: <8ViMc.368$NV3.301_at_trndny01>

"Neo" <neo55592_at_hotmail.com> wrote in message news:4b45d3ad.0407231054.327a5a41_at_posting.google.com...
> > > > > Could you show how to explicity represent the following info in
RM:
> > > > > john take test.
> > > > > john get 95.
> > > > > (john get 95) for (john take test).
> > > >
> > > > PERSON SCORE
> > > > John 50
> > > > Mary 75
> > >
> > > A program could derive each tuple's relationship to a person and score
> > > (ie tuple1's person is john, tuple1's score is 50. It doesn't encode
> > > the original info explicitly.
> >
> > Because it is not necessary (or proper) to refer to the tuple by its (row)

> > number. Sets are not ordered, so tuple numbers are meaningless.
> > They can change.
>
> The expression "tuple1" is a short method of identifying one of the
> two tuples as listed above instead of saying "the tuple whose
> attribute person has the value john and whose attribute score has the
> value 50". The expression "tuple1" is not meant to imply its position
> among tuples in the db or that its position couldn't change.
>
> By the way, your response to "[above table] doesn't encode the
> original info explicitly" being "Because it is not necessary (or
> proper) to refer to the tuple by its number" is illogical as the short
> method of referring to tuple by its position as listed above does not
> counter that the above table doesn't enode the original info
> explicitly.
>
> > Besides, why refer to a tuple by its number rather than by the Primary

Key?

>
> Because no one has defined a primary key on the relation and neither
> is it a requirement. The "1" in "tuple1" is meant to identify tuple's
> position as listed above, not its ID or its position in the db.
>


> > > > SELECT person||' scored '||score||' in the exam.' FROM =test_scores;

> > > > John scored 50 in the exam.
> > > > Mary scored 75 in the exam.
> > >
> > > SQL statement is providing relationship between the data, not data in
db
> >
> > Ummm, dude, somewhere along the line, some bit of code is going to provide

> > the relationship, unless you've invented a psychic computer interface.
>
> Why would you want to encode the relationship between things in code
> (or SQL statements) when it can be done with data in the db, as does
> XDb2/TM, as shown at www.xdb2.com/Example/StudentActivityScore.asp ?
>
> > the programmer must know all possible questions that will be asked,
> > and all possible relationships among the data- all before entering any

data.

>
> A long-term goal of mine is for the "programmer" to be
> computer/software and for it to know relationships among the data, the
> relationships should be entered into the db.
>
> > .. system works well with known sample data under controlled conditions.
>
> A long-term goal of mine is for a system to work well with unknown
> data under uncontrolled conditions, somewhat like a human being.
>
> > I suspect you have an interest in AI, and it looks like you are trying

to
> > connect an inference engine to an rdb, but you tripped over the db theory.

>
> XDb2/TM stores the following things explicitly including
> relationships, in a NULL-less and normalized manner. Could you untrip
> me and show how to represent the following explicitly using RM theory?
>
>  john take test.
>  john get 95.
>  (john get 95) for (john take test).

I've tried to untrip you before. So have many others, but your shoelaces are tied in a Gordian knot.

Best wishes for the future... Received on Sat Jul 24 2004 - 03:26:28 CEST