W3C home > Mailing lists > Public > www-rdf-rules@w3.org > October 2001

Self-Correction

From: Sandro Hawke <sandro@w3.org>
Date: Thu, 04 Oct 2001 19:15:47 -0400
Message-Id: <200110042315.f94NFl413194@wadimousa.hawke.org>
cc: Drew McDermott <drew.mcdermott@yale.edu>, www-rdf-rules@w3.org

Arg.  The formal-logic part of my knowledge base was still swapped out
(making room for C++ and techniques to keep reduce sibling rivalry),
and the page fault went undetected.

I really didn't mean to say this:

> I don't exactly understand the difference, myself.  I appreciated
> Gerd's comment above, because it validated by own confusion over which
> way to understand a logic program.  I think n3 logic [1] [2] shows the
> same confusion.  The syntax and terminology ("log:implies") suggest
> implication, but its usage in forward chaining by the implementation
> (cwm) sounds like inference rules.  (cwm actually will infer new rules
> and use them.  What does that sound like?)

because while I do see how a logic program (or n3 logic RDF graph)
could be treated as expressing a set of inference methods, it seems
clear to me that both a pure logic program and an n3 logic graph are
intended to be treated as logical formulas, and processed via
generalized modus ponens.   The goal of the cwm processing is to
enumerate the entailment of the logic graph.

And cwm looking in its deductions for more "rules" it should follow
is, I think, just an odd way to handle a certain structure formula.
That is: 
    a --> (b --> c)
could just be rewritten:
    ~a | (~b | c)
    ~a | ~b | c
    ~(a & b) | c
    (a & b) --> c
which is nice and simple.

    -- sandro
Received on Thursday, 4 October 2001 19:17:36 GMT

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