Many rules programmers prefer splitting an OR rule into multiple rules, in
order to minimize the complexity of the rules, standardize the format, and
make rules understandable and maintainable long-term. Splitting a rule
provides an implicit OR mechanism because of how rules are activated anyway.
So, you don't lose expressive power by not being able to OR explicitly on
the LHS.
> -----Original Message-----
> From: Ernest Friedman-Hill [mailto:[EMAIL PROTECTED]]
> Sent: Monday, July 19, 1999 6:30 AM
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]
> Subject: Re: JESS: OR and AND in rules
>
>
> The "or" conditional element is something I'm promised to add for a
> while. It requires some structural changes that are trickier than
> you'd think (at least, so far, trickier than I've been able to clearly
> lay out.) Until then, as a user suggested, multiple rules are the only
> way to alternate patterns; alternatives within a single slot can use
> the "or" function or the '|' predicate constraint (see 5.0a6 Manual
> section 2.8.1).
>
> I think Message UK wrote:
> >
> > Hi all. I would like to be able to use an OR in a rule,
> like "if this is the
> > case" OR "this is the case" then fire rule X.
> >
> > In some rules I have listed several conditions, which I
> have assumed works
> > as an AND:
> >
> > (defrule worried_AIDS
> > >> ?u <- (user(hiv_status "pos"))
> > >> ?e <- (enquiry (type G3)(value "done"))
> > =>
> >
> > ...etc...
> >
> > is that right? is it ANDed? How do I do an OR? (if it's
> possible)? And if
> > the above is in fact an OR, how do I do an AND??!!
> >
> > Tres thanks. Debbie Lampon
> >
> >
> > ______________________________________________________
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> >
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>
>
> ---------------------------------------------------------
> Ernest Friedman-Hill
> Distributed Systems Research Phone: (925) 294-2154
> Sandia National Labs FAX: (925) 294-2234
> Org. 8920, MS 9214 [EMAIL PROTECTED]
> PO Box 969 http://herzberg.ca.sandia.gov
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>
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