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Re: [Core][PRD] Definition of safeness

From: Sandro Hawke <sandro@w3.org>
Date: Tue, 16 Jun 2009 06:44:08 -0700
To: Christian De Sainte Marie <csma@fr.ibm.com>
cc: RIF <public-rif-wg@w3.org>
Message-ID: <2831.1245159848@waldron>

I have an naive question about our effort to define of safeness.

We say, "Intuitively, safeness of rules guarantees that when performing
reasoning in a forward-chaining manner, it is possible to find bindings
for all the variables in the rule so that the condition can be
evaluated. "

Is there any variation among PR systems, where there are rules for which
some systems can find such bindings and others cannot?  If not, is it
likely PR systems will emerge which will differ from the crowd about
which rules are safe?  Since I haven't heard anyone argue about our
definition of safeness in these terms (eg "this is safe for clips but
not jess"), I'm guessing the answer to both is No.

In that case, can't our single, normative definition one sentence, like:
"A rule is safe if it is possible to find bindings for all the variables
in the rule such that the condition can be evaluated."  That should
probably be expanded a little (including explaining binding patterns for
externals), but I'm not seeing why we need to standardize what amount to
an algorithm for determining this case.  By all means, we could provide
one or more helpful, non-normative guides to how to determine if
bindings are findable, but if there's no actual disagreement likely
among implementors, I don't see why we're trying to standardize it.

   -- Sandro
Received on Tuesday, 16 June 2009 13:44:15 GMT

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