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Entailment versus implication

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Tue, 05 Feb 2002 10:49:54 +0200
To: RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B8856952.D373%patrick.stickler@nokia.com>
    
The recent discussions regarding reification and entailment
have made me suspect that I am not understanding (again) the
MT vocabulary.

My understanding of entailment (coming from a computational
linguistics background) is that a statement is entailed by a
set of statements if it is logically implied by the set
of statements (i.e. a triple is entailed by an RDF graph if
it is logically implied by that RDF graph).

To me, "entailment" means that adding to the graph does not
increase the information already there, even if it makes some
information explicit that was otherwise implicit. Everything is
already there. E.g.

  Club members get a discount.
  Jill is a club member.

entails

  Jill gets a discount.


So, when folks say that

_:B ex:father #Bob .
_:B ex:gender ex:Male .
_:G ex:father #Bob .
_:G ex:gender ex:Female .

entails

_:B ex:gender ex:Female .
_:G ex:gender ex:Male .

I start to wonder if we are all talking about the same thing.

Certainly the first set of triples do *not* imply the latter
pair of triples. How could they? Where is the basis for such
an implication? The existence of some bNode?

Where are we having the breakdown in communication? (or
are we ;-)

Patrick

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Tuesday, 5 February 2002 03:53:02 EST

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