If you could retract 'a' as it is counted, a simpler solution that does not
require the use of defglobal would be:
(defrule combine-all-facts-1
?single <- (a ?X)
?combo <- (A $?all)
=>
(retract ?single ?combo)
(assert (A ?all ?X))
)
(reset)
(assert (A))
Now, each time an 'a' fact is asserted, it is added to the 'A' fact and
retracted.
This way, you don't have to wait until you run out of 'a's before you combine
them,
and you can keep the 'a's coming through out the program run cycle, knowing that
they will be added to the 'A' fact immediately after they are asserted.
Ernest Friedman-Hill wrote:
> You just need to store them somewhere while you add them up. You could
> use a fact, or, as I've done here, use a
> defglobal. combine-all-facts-1 will fire once for each 'a'
> fact. combine-all-facts-2 will fire after all combine-all-facts-1
> activations have fired.
>
> (defglobal ?*all-as* = (create$))
> (defrule combine-all-facts-1
> (a ?X)
> =>
> (bind ?*all-as (create$ ?X ?*all-as*)))
>
> (defrule combine-all-facts-2
> ;; don't run until the other rule is finished
> (declare (salience -1))
> =>
> (assert (A ?*all-as*)))
>
> You could avoid using salience if you could retract each 'a' as it was
> counted; then just make the second rule fire on (not (a)).
>
> I think S Yang wrote:
> >
> > Thanks for the prompt reply. However, the answer
> > works only if the number of facts to be combined
> > is known. The problem I am facing is that the
> > facts are all in the form of (a ...), but I don't
> > know how many in advance. I just need to combine
> > them all.
> >
> > Thanks again for the help.
> >
> > Sam Yang
> >
> > At 07:15 15/04/99 -0700, you wrote:
> > >(defrule combine-facts
> > > (a ?X)
> > > (a ?Y&~?X)
> > > (a ?Z&~Y&~X)
> > > =>
> > > (assert (A ?X ?Y ?Z)))
> > >
> > >Something like that?
> > >
> > >
> > >I think S Yang wrote:
> > >>
> > >> Dear All,
> > >>
> > >> I am trying to write some JESS programs. It is easy to
> > >> start but to write something useful, it is much more
> > >> difficult than other languages. One of the problwm I
> > >> often face can be simplified as the following:
> > >>
> > >> Given a list of facts:
> > >> (a 1)
> > >> (a 2)
> > >> (a 3)
> > >> ...
> > >>
> > >> How do you construct a fact?
> > >> (A 1 2 3 ...)
> > >>
> > >> Thanks in advance.
> > >>
> > >> Sam Yang
> > >>
> > >>
> > >> ---------------------------------------------------------------------
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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
> > >Livermore, CA 94550
> > >
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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
> Livermore, CA 94550
>
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--
--------------------------
Dr. Hisham Assal
CAD Research Center
Cal Poly State University
San Luis Obispo, CA 93407
Tel. (805) 541 3750
Fax. (805) 541 8296
email: [EMAIL PROTECTED]
http://www.calpoly.edu/~hassal
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