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Re: Inference in daml

From: Sean B. Palmer <sean@mysterylights.com>
Date: Mon, 18 Jun 2001 01:59:58 +0100
Message-ID: <09c101c0f793$37745d40$66da93c3@z5n9x1>
To: "Geoff Chappell" <geoff@sover.net>
Cc: <www-archive@w3.org>
Taking this off-list (actually, to www-archive) because my
understanding is a bit murky from here on in...

> But can't you make use of logical equivalents? i.e. "p->q" has
> the same truth table as "q or not p" -- which can be expressed
> in daml.

But I think that once you go from "p->q" to "q or not p" which in DAML
is more like "union of q and the compliment of p" as you have
demonstrated, you can only rely on the semantics (i.e. rules,
inferences) of DAML to provide the implications, because it lacks the
terms required to become a full FOL language. DAML is there to provide
a simple ontology framework, not to state the full range of inferences
up front. It does howver provide you with enough terms to create
simple statements from which many inference rules can be derived.

> The question is, if you express the rule in that form (by defining
> a class of things that are q or not p and say that all things are
> members of that class) will a processor that correctly interprets
> the semantics of the daml language necessarily interpret the rule
> as an implication?

It should do, but in general RDF inference engines, you'll probably
have to feed the rules in yourself, which is useful because
practically you only want to come to one particular conclusion,
although you could quite easily generate hundreds of others. The
complication arises when you want one particular bit of information,
but have to go through several different inferences to get there,
which you don't care about (i.e. don't want on the output).

Once again, TimBL's log namespace, DAML, and RDF Schema make a
powerful mix.

--
Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
:Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Sunday, 17 June 2001 21:07:17 GMT

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