Re: [TED] Action-188, ISSUE: production rule systems have "difficulty" with recursive rules in RIF Core

Sandro Hawke wrote:
[...]
> We'll need some normative Conformance text at some point, something a
> bit like:
>    http://www.w3.org/TR/owl-test/#consistencyChecker

True.

> We could say something like (as a rought first cut):
>
>   A "RIF Core Rule Engine" is a rule engine which can perform sound
>   and complete reasoning on any rule set which can encoded in one or
                                                    ^ be 
>   more RIF Core documents.  It must be able to answer all queries
>   against the deductive closure of the ruleset, where a query is
>   equivalent to a RIF Core anticedent, and to answer a query means to
                                ^e 
>   provide every matching set of bindings to the variables in the
>   anticedent.
       ^e 

I agree.

> At the moment, unless some new information comes along, I'm inclined to
> agree that we need to leave recursive Horn rules out of the core.

All of the rule sets that I use for my practical work have
some rules that are recursive, even some of them also have
mutual predicate dependency like
  pred3(X,Z):- pred1(X,Y), pred2(Y,Z).
  pred2(X,Z):- pred3(X,Y), pred4(Y,Z).
 

-- 
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/