Hi,
I'm actually evaluating Jess and have a problem with backward chaining.
Here is what I want to solve: I want to "calculate" in a backward chaining
manner the ancestors of an individual.
My facts are something like
(Parent P P1)
(Parent P1 P11)
(Parent P11 P111)
and so, I would like to get the ancestors of P11. Thus, after executing my
rules, I would like to get those new facts :
(Ancestor P P11)
(Ancestor P1 P11)
Thanks for your help.
Claude.
Here is my complete code :
; =====================================
; file name : testbw.txt
; =====================================
(do-backward-chaining Ancestor)
(defrule print-ancestor-P11
(Ancestor ?x P11)
=>
(printout t "Done." crlf)
)
(defrule create-ancestor1
(need-Ancestor $?)
(Parent ?x ?y)
=>
(printout t "1-Calculating ancestor of " ?y crlf)
(assert(Ancestor ?x ?y))
)
(defrule create-ancestor2
(need-Ancestor $?)
(Ancestor ?x ?y)
(Parent ?y ?z)
=>
(printout t "2-Calculating ancestor of " ?z crlf)
(assert(Ancestor ?x ?z))
)
(reset)
(assert (Parent P P1))
(assert (Parent P1 P11))
(assert (Parent P11 P111))
(run)
; =====================================
Here is the trace of the execution :
Jess> (batch mydata/testbw.txt)
1-Calculating ancestor of P111
1 Jess> (facts)
f-0 (initial-fact)
f-1 (need-Ancestor nil P11)
f-2 (need-Ancestor nil nil)
f-3 (Parent P P1)
f-4 (Parent P1 P11)
f-5 (Parent P11 P111)
f-6 (Ancestor P11 P111)
For a total of 7 facts.
Jess>
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