Dear Alex, (01)
> It seems relationship "DL versus Prolog" is more complicated than
> I thought ( http://arxiv.org/ftp/arxiv/papers/0711/0711.3419.pdf ) (02)
Mitre is one of the companies that I was thinking of when I said that
many large groups translate RDF and OWL to Prolog. Following is an
excerpt from the abstract of that paper: (03)
... we are developing the SWORIER system, which enables efficient
automated reasoning on ontologies and rules, by translating all
of them into Prolog and adding a set of general rules that properly
capture the semantics of OWL. We have also enabled the user to make
dynamic changes on the fly, at run time. This work addresses several
of the concerns expressed in previous work, such as negation,
complementary classes, disjunctive heads, and cardinality, and it
discusses alternative approaches for dealing with inconsistencies
in the knowledge base. (04)
The Mitre approach has many interesting features, and I recommend that
paper as an important survey. At VivoMind, we also use Prolog, but
we have a different approach that involves multiple agents that use
a variety of reasoning methods, both logical and analogical. (05)
> May be there is a direct comparison of reasoning "power" in different
> systems? Something like reasoners competition;) (06)
Following is a paper I wrote about some of the issues: (07)
http://www.jfsowa.com/pubs/fflogic.pdf
Fads and fallacies about logic (08)
If you are interested in competitions among theorem provers, you might
look at the Thousands of Problems for Theorem Provers (TPTP): (09)
http://www.tptp.org/ (010)
> In our project we have just two goals:
> - transform RDB to KB. (Because knowledge is better than data;)
> - rebuild our application system on top of KB reasoning engine.
> (and here OWL-DL right now is mandatory;) (011)
Whenever anybody throws around words like "knowledge" and "data",
that is a sign of a smoke screen designed to confuse the pointy
haired bosses who know nothing about either one. Nearly *every*
large knowledge base (such as Cyc, which is the largest one
ever implemented) is designed to use a relational database to
store the low-level facts. (012)
Whenever OWL-DL is declared "mandatory", that is a sign that some
pointy-haired boss was sufficiently confused to drink the Kool-Aid.
There are horror stories about large RDB systems in the US that
were "mandated" to be translated to RDF with disastrous results. (013)
The basic issue is that RDBs use indexes to find the relevant
data in logarithmic time. When the index cannot be used because
it is necessary to process an entire column, the RDB pages the
data in an orderly fashion. (014)
The problem with SPARQL is that RDF is not designed to support
indexing. The people who built so-called "triple stores" say
that they're efficient because they run in RAM. But any DB that
fits in RAM is a toy. If you take a non-toy DB and map it to
RDF, it doesn't fit in RAM. Furthermore, those triples aren't
indexed, and they're not designed to be paged in an orderly
fashion. The result is endless disk thrashing. (015)
If I had a pointy-haired boss who mandated the translation
of an RDB to RDF, I would immediately send my resume to every
reasonable employer -- because you can be certain that this
system is going to be a disaster. And the PHB is going to save
himself by blaming the failure on the people who work for him. (016)
John (017)
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