On 2/3/13 9:28 AM, John F Sowa wrote:
> Folks,
>
> This discussion raises some of the same points as Ed Barkmeyer's
> note in the thread "FW: Big Data Logic Stack?"
>
> I sent a slightly edited version of Ed's note and my response to the
> conceptual graph email list. Jack Park responded with some pointers
> to the Cascalog web site. (Copy below with my response to Jack.)
>
> Datalog is essentially a subset of Prolog that is designed for
> processing a database. It has a much cleaner notation for logic
> than the SQL WHERE clause or SPARQL. It also avoids the nonlogical
> features of NULL values in SQL or the filters of SPARQL. (01)
I don't understand your reference to FILTERS in SPARQL. Please remember,
SPARQL query patterns are basically triples patterns expressed in Turtle
notation. The existence of FILTERS is very peripheral, certainly not
playing the same role as a WHERE CLAUSE in SQL . (02)
SELECT ?s WHERE {?s a ?o} (03)
For instance, I don't need a filter in the above to retrieve instances
of ?o . (04)
>
> If the DAML project had adopted Datalog as their primary notation
> back in 2005, they would have a foundation that could support both
> relational and graph databases with equal facility. (05)
You can achieve that today with SPARQL combined with SQL, as implemented
in Virtuoso. Likewise, with SPARQL 1.1 which includes Insert, Update,
and Delete functionality, you can pretty much match and exceed SQL using
SPARQL when the underlying relational data is sets of 3-tuples.
>
> People who don't know logic never liked Prolog. They keep designing
> rule-based languages with an English-like front end. Back in the
> 1990s, Norbert Fuchs and his students developed ACE as an English-like
> front end to Prolog (or Datalog).
>
> Fuchs and his students also adapted ACE as a front end to OWL, and
> all the software is available for a free download. For more info,
> see the Wikipedia article on ACE:
>
> http://en.wikipedia.org/wiki/Attempto_Controlled_English
>
> Recommendation: Adopt Datalog as the interface to both relational and
> graph DBs. (06)
This isn't about a specific language per se. You can use Turtle to
implement a rules language as demonstrated by SPIN [1]. The problem in
the past is that RDF/XML mucked up the entire Semantic Web realm. (07)
Links: (08)
[1]
http://www.w3.org/Submission/2011/SUBM-spin-modeling-20110222/#spin-rules-construct (09)
-- SPIN example (010)
Kingsley
> Use ACE as a foundation for an English-like interface to
> the Semantic Web, RDBs, and rule-based languages.
>
> John
> _______________________________________________________________________
>
> On 2/3/2013 1:13 AM, Jack Park wrote:
>>> Two interesting links which appear to be related are these:
>>>
>http://nathanmarz.com/blog/introducing-cascalog-a-clojure-based-query-language-for-hado.html
>>> and
>>> https://github.com/nathanmarz/cascalog
> Thanks for those pointers.
>
> Cascalog looks like a good adaptation of Datalog to Hadoop.
>
> In the early 1980s, Ted Codd came across Prolog, and his immediate
> reaction was "I wish I had invented that."
>
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> (011)
-- (012)
Regards, (013)
Kingsley Idehen
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