Re: Interpretation of Relations
Date: Mon, 22 Jan 2007 21:34:42 GMT
Message-ID: <2007012307342377923-usenet_at_thurboncom>
On 2007-01-22 23:39:14 +1000, Bob Badour <bbadour_at_pei.sympatico.ca> said:
>>
>
> The RM includes the operations on relations by which one does the
> inferencing. Does it not?
Depending on how you interpret relations into predicates, I would say that JOIN and PROJECT are kinds of inferencing rules. But they seem quite different to modus ponens.
>
>> >> Anyway, I've rambled on quite a bit. The ideas are pretty new to me, >> still in development, and really, I'm getting ahead of myself because I >> still don't fully understand the RM.
>
> Would the observation that the relational calculus is basically 1st
> order predicate logic help you understand it better?
Not really. Well, I guess its validation that I'm not completely crazy.
I was actually starting from the assumption that the relational
calculus could be embedded in 1st order logic.
I will feel like I understand the RM when I can answer the question:
for a relational theory (by theory I think I mean a set of relvars - a
set of 'instantiated' relations), what is the corresponding logical
theory (set of grounded wffs).
I have other questions, too, of course. What does it mean to close a set of relations under consequence? (Is is the repeated application of JOIN and PROJECT?) What is the analog of, say, material implication? What is a valid implication? What parts of logical consequence do I lose when I represent my knowledge in a relational form.
I appreciate that these are probably basic things, but I'm really having trouble finding any information on it, so I'm just working my way through it. I'll probably understand it better this way anyway, although references would be appreciated.
Cheers,
Joe
Received on Mon Jan 22 2007 - 22:34:42 CET