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[BLD] equality use cases + implementation announcement

From: Alexandre Riazanov <alexandre.riazanov@gmail.com>
Date: Thu, 30 Jul 2009 17:52:33 -0400
Message-ID: <a7f786b70907301452m385f4f02p706b1f1952f78ad@mail.gmail.com>
To: public-rif-comments@w3.org
Hi everybody,

I am working on prototype for semantic querying of relational databases
(http://www.freewebs.com/riazanov/query_answering.pdf),
and RIF BLD is envisaged as one of the input languages (TPTP, OWL 2, SWRL
and Derivational RuleML are the others).
Since (a branch of) the Vampire prover is currently the core of the system,
it will essentially become a rule engine for BLD, supporting query
answering.

The first implementation will simply convert BLD to TPTP, so it will be
useable with all TPTP reasoners.
Since it's basically just a Java API, the toolkit may be useful for purposes
other than TPTP conversion:
it will have a factory for the abstract syntax + JAXB-based parser/renderer.

All the software will be open source. I am expecting to publish an alpha in
September.



Since the positive equality in BLD is still in danger, I would like to
mention a couple of
examples I came across recently, working on the RDB stuff.

Use case 1. Semantic querying requires semantic mapping of RDB schemas,
e.g.,
by linking the tables to application domain concepts and relations.
Typically,
a part of a schema is just a declaration of functional dependencies between
attributes
of tables. These can be easily expressed if our language allows equality,
e.g.
the following rule states that the table_person.name functionally depends on
table_person.sin :

?NAME1 = ?NAME2
   :-
And
  (
      table_person(sin -> ?SIN, name -> ?NAME1),
      table_person(sin -> ?SIN, name -> ?NAME2)
   )


Such rules can be used by the reasoner for search space reduction, e.g, by
contextual rewriting.


Use case 2. Suppose we use several RDBs designed by different people for
different purposes.
The same entities can be represented differently in different DBs. For
example, the same
person can be identified with his SIN in one DB, and with a surrogate
integer key in another DB:

person_for_sin(?SIN) # Person
    :-
db1.table_person(sin -> ?SIN, name -> ?NAME)



person_for_key(?KEY) # Person
    :-
db2.table_person(key -> ?KEY, sin -> ?SIN, name -> ?NAME)


hasSIN(person_for_key(?KEY),?SIN)
    :-
db2.table_person(key -> ?KEY, sin -> ?SIN, name -> ?NAME)




So, for cross-querying we absolutely need something like this:

person_for_sin(?SIN) = ?P
   :-
And(
        ?P # Person,
        hasSIN(?P,?SIN)
      )


Please note that these are just recent examples that are fresh in my mind.
I have seen others.



Cheers,
======================================
Dr. Alexandre Riazanov (Alexander Ryazanov)
Montreal, Canada
cell: +1 - 514 - 961 86 89
http://www.freewebs.com/riazanov/
http://www.linkedin.com/in/riazanov
======================================
Received on Thursday, 30 July 2009 21:53:13 GMT

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