- From: Gerd Wagner <wagnerg@tu-cottbus.de>
- Date: Sat, 28 Jan 2006 13:51:20 +0100
- To: "'Peter F. Patel-Schneider'" <pfps@inf.unibz.it>, <jos.deroo@agfa.com>
- Cc: <public-rif-wg@w3.org>
>> I would have thought that
[my rewriting:]
{ p v q => r. }
and
{ p => r. q => r. }
>> are equivalent rulesets, no?
> Well obviously not at least in some readings, as they produce
> different answers.
Their equivalence (according to the principle called
"disjunction in the premise") is generally valid in all
kinds of standard logics if "=>" is read as the implication
connective. And it also holds in disjunctive logic programs.
However, they may not be equivalent, if "=>" is read as a
rule operator (not an object language symbol) having the
epistemic flavor of requiring the condition to be "known"
(it's not the same to know just p v q or to know p or q).
Since we are assuming standard classical logic (do we?),
reading rules as plain Horn formulas, Jos is right.
-Gerd
--------------------------------------------
Gerd Wagner
http://www.informatik.tu-cottbus.de/~gwagner
Brandenburg University of Technology
at Cottbus, Germany
Received on Saturday, 28 January 2006 12:54:20 UTC