Re: database: prolog and relational

Hi

I want to suggest you an old book by J.D.Ullman Principles of Database & Knowledge-Base Systems.

Besides, have you heard of Datalog?
It's a simpler (function-free but not constant-free) version of Prolog wihch was intended for the treatment of DB or KB by means of clausal logic. There are some good papers by Ceri and/or Gottlob about that available around (e.g. on Citeseer).
Similar multi-relational representations are being employed in AI especially in KR&R and ML dealing with deductive and inductive databases.

Hope it helps the discussion.

N.

mAsterdam ha scritto:
> Warning: crosspost
>
> (I apologize if am crossposting wrongly, I've never done that before).
>
> This seems like an appropriate time to call in help from another newsgroup.
>
> To the people of comp.lang.prolog:
> Could you please give some comment on this thread?
> There don't seem to be many people
> who know prolog in comp.database.theory
> Maybe there are some people at c.l.prolog
> who do know RDBMS.
>
> Paul wrote:
>
> > x wrote:
> >
> >> There are other differences. For example there are no candidate
> >> or foreign keys in Prolog.
> >
> >
> > Well candidate and foreign keys are really just special cases of
> > constraints which have been given an elevated status. Can't you say in
> > Prolog something like: "values in this column are unique" or
> > "values in this column must also be in this other column
> > in this other table"? (I'm not even sure if Prolog has
> > tables or columns but I guess it must have
> > something analogous)
> >
> >>> OK, I'm not that familiar with Prolog.
> >>
> >> If you are interested, you can start at:
> >> http://www.lim.univ-mrs.fr/~colmer/
> >> http://www-lp.doc.ic.ac.uk/UserPages/staff/rak/rak.html
> >
> > thanks, I'll check them out.
> >
> >>>> And first order logic is "incomplete" also
> >>>> because of the "in all models" stuff.
> >>>
> >>> I don't really understand what your problem is with this.
> >>>
> >>> Here's another statement of Godel's Completeness Theorem:
> >>> "If T is a set of axioms in a first-order language, and a
> >>> statement p holds for any structure M satisfying T, then
> >>> p can be formally deduced from T in some appropriately
> >>> defined fashion."
> >>>
> >>> They're using the word "structure" for "model" but the
> >>> same concept. Now surely this is just what you'd
> >>> intuitively expect?
> >>>
> >>> For example consider our theory T is group theory.
> >>> One structure that satisfies the group theory axioms
> >>> is that of abelian (commutative) groups. In this
> >>> structure every element commutes with
> >>> every other element. But this is not the case
> >>> for the general theory of groups. For something to be
> >>> a universal property of groups, it must be true for
> >>> *every* possible structure that satisfies the group
> >>> axioms. And the theorem says that then you can
> >>> *always* prove the property in the theory T
> >>> alone (i.e. without reference to any of the
> >>> structures based on the theory T).
> >>
> >>
> >> But I'm interested in properties of a particular structure S,
> >> not in the properties of some theory T that happen to describe
> >> some aspects of S.
> >
> > But first-order logic is "special" in some sense because
> > it is the very foundation of everything you do.
> > It's the theory T above, we're not interested in any
> > specific structure S, we just want to know that for
> > any S, first-order logic does enable us to talk
> > about S completely (in the sense defined above).
> > This is the very definition of what it means for
> > first-order logic to be complete. What the properties
> > of any particular structure S are is a totally different
> > question.
> >
> >>> I'm acutally wondering as well whether all this talk of
> >>> Godel is irrelevant anyway because in databases we are
> >>> only dealing with finite sets of axioms.
> >>> Possibly second order logic is complete
> >>> when you have a finite number of axioms?
> >>> I'll have to do a bit more Googling.
> >>
> >> In databases we deal with facts, not with finite sets of axioms.
> >
> > I'm saying these are the same thing. Each tuple is a
> > logical proposition, a fact, which is an axiom in our
> > database (our "theory").
> >
> >> Metamathematics deal with sets of axioms and theorems.
> >
> > Surely metamathematics is the language you use to talk
> > about and manipulate your axioms and
> > theorems: i.e. logic. Your axioms and theorems are the
> > mathematics itself.
> >
> >> Have you seen :
> >> http://www-csli.stanford.edu/hp/CVandNR.pdf
> >> http://www-csli.stanford.edu/hp/Reflections.pdf
> >
> > Yep, I've had a brief look. Seems quite philosophical rather
> > than mathematical, I'll hopefully get time to look at them in
> > more depth soon.
>
>
> TIA
Received on Thu Jun 10 2004 - 13:46:18 CEST