The Rete algorithm used by Jess allows for multiple different indices
and filters at different points in the discrimination network. You can
read something about what Jess does in the manual itself, in the
chapter on the Rete algorithm.
But as far as indexing for joins like the below: Jess does neither of
your two alternatives. It indexes not on all the slots, nor just the
first slot; it indexes adaptively on one or more slots that are used
in a particular join. So in your rule below, the join between the
first two patterns indexes the "first" slot in "s", and the "second"
slot in "hyp". The next join indexes "first" in hyp, and "first" in "s".
On Oct 10, 2008, at 5:22 PM, Baxter Young wrote:
Dear Sir,
I am new to Jess and I am not sure how Jess indexes tuples.
It seems that it indexes on all arguments and not only the first
argument (like many prolog systems). I just want to check if this is
correct.
For instance, I have the program below that finds all hyponyms of all
words in english in WordNet.
The find_testAllHyponyms rule, uses the template
(hyp (first ?synset_id2) (second ?synset_id1))
where the second argument is bound, where the first one is bound.
I get the same time if I compute all the hyponyms (first argument
bound) or all the hypernyms (second argument bound), which brought me
to the conclusion that Jess indexes on both arguments.
Regards,
Paul Fodor
; define templates
(deftemplate s (slot first) (slot second))
(deftemplate hyp (slot first) (slot second))
(deftemplate testAllHyponyms (slot first) (slot second))
(defrule find_testAllHyponyms
(s (first ?synset_id1) (second ?word1))
(hyp (first ?synset_id2) (second ?synset_id1))
(s (first ?synset_id2) (second ?word2))
=>
(assert (testAllHyponyms (first ?word1) (second ?word2)))
)
(defquery query-testAllHyponyms
(testAllHyponyms (first ?first) (second ?second))
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(printout t crlf "wn_s.clp" crlf)
(reset)
(load-facts "wn_s.clp")
;(facts)
(printout t crlf "wn_hyp.clp" crlf)
(load-facts "wn_hyp.clp")
;(facts)
(bind ?tmx (call java.lang.management.ManagementFactory
getThreadMXBean))
(deffunction cputime () (return (* (?tmx getCurrentThreadCpuTime)
1E-9)))
; get times
(bind ?starttime_wall (time))
(bind ?starttime_cpu (cputime))
(run)
(bind ?testAllHyponyms_result (run-query* query-testAllHyponyms))
(bind ?count 0)
(while (?testAllHyponyms_result next)
(printout t "")
(++ ?count)
)
(printout t "the number of answers = " ?count crlf)
(bind ?endtime_cpu (cputime))
(bind ?endtime_wall (time))
(bind ?walltime (- ?endtime_wall ?starttime_wall))
(bind ?cputime (- ?endtime_cpu ?starttime_cpu))
(printout t "Cpu time = " ?cputime crlf)
(printout t "Wall time= " ?walltime crlf crlf)
;(facts)
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Ernest Friedman-Hill
Informatics & Decision Sciences, Sandia National Laboratories
PO Box 969, MS 9012, Livermore, CA 94550
http://www.jessrules.com
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