Re: JESS: Defrule ordering woes
Basically, the problem is that salience doesn't mean much in a multithreaded system. A rule may have very low salience, but if it is activated before other rules of higher salience are activated, then it may be fired (on the run thread, different from the thread where the rule was activated) before those other rules have a change to displace it from the top of the agenda. In this case, your low-salience delete-timer-events rule is firing as fast as the new facts appear, before the quarter-minute and minute rules have a chance to fire. delete-timer-facts matches every temporal-event fact as soon as it appears, and furthermore, the patterns are identical to those of the rule show-seconds, so both of those are being activated together, and salience makes show-seconds fire first. But the other two rules have slightly different patterns, so they're activated at a slightly different time (the order here is arbitrary and, as you've seen, depends on the order in which the rules are defined.) One more definite solution, rather than yours which depends on undefined behavior, is to modify delete-timer-facts so that it allows a few timer facts to stay around before deleting them -- i.e., something like (defrule delete-timer-events Delete any old temporal-event facts (declare (salience -100)) ?t - (temporal-event (ctm ?ctm)) (not (temporal-event (ctm ?ctm2:( (- ?ctm 1) ?ctm2 = ;;(printout t Retracting ?t crlf) (retract ?t)) Now, the underlying Jess behavior that causes this is something we've talked about on the list before. Basically, what Jess does now is allow rules to initiate firing on one thread during pattern matching occurring on another thread; if a single fact activates three rules, then the first activation can fire before the second rule is even placed on the agenda. This has very good liveness characteristics, but leads to inversions like what Mitch is seeing here. An alternative is for the agenda to be locked during pattern-matching, so that the run-until-halt thread would not be able to pop an activation from the agenda until after all the activations from a single assertion event were present. This would make Mitch's problem go away, but with a potential performance loss in densely multithreaded operation. Anyone want to comment? I think Mitch Christensen wrote: [Charset iso-8859-1 unsupported, filtering to ASCII...] Hey, I'm having trouble understanding why reordering 'defrule' statements in a Jess script changes how the program runs. Specifically, I've created a UserFunction timer that asserts a 'temporal-event' fact every second (source attached). Then I have a simple Jess script (also attached) that loads and executes the UserFunction, and then defines 3 debugging rules. These rules do a printout at each second, quarter-minute and minute (there is also a rule to retract old facts). My problem is that the seconds rule always fires, while quarter-minute and minute rules are sporadic (sometimes they fire sometimes not). If I simply re-order the rules, putting the minute rule first, the quarter-minute rule next and the second rule last, things seem to work fine. Now, if I understood why, I'd be in pretty good shape. ;) Any suggestions? -Mitch P.S. 'ctm' is for CurrentTimeMillis. It's the only way I could find to keep rules from firing more than once, i.e. only fire if this fact has the lowest ctm in working memory and to fire in the proper order should multiple temporal-event facts be asserted between (runs). [Attachment, skipping...] [Attachment, skipping...] - Ernest Friedman-Hill Distributed Systems ResearchPhone: (925) 294-2154 Sandia National LabsFAX: (925) 294-2234 PO Box 969, MS 9012 [EMAIL PROTECTED] Livermore, CA 94550 http://herzberg.ca.sandia.gov To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED]
Re: JESS: Strange behavior when using Jess modules
Hi, a few days ago I posted a question concerning the use of modules and so far I did not get any answer. Is there really no one who could help me to figure out what is wrong with the following example? Felix Here an interesting issue. (I hope) Assume the rules are structured into 3 modules (MAIN, A, and B) which contain statements to assert ordered facts as shown in this example: ; ; c:/jess/test/A.clp ; (defmodule A) (defrule forA (MAIN::initial-fact) = (assert (testfact A in A)) (assert (testfact B in A))) ; ; c:/jess/test/B.clp ; (defmodule B) (defrule forB (initial-fact) (MAIN::testfact B in MAIN) ; This causes the trouble = (assert (testfact A in B)) (assert (testfact B in B))) ; ; c:/jess/test/MAIN.clp ; (batch c:/jess/test/A.clp) (batch c:/jess/test/B.clp) (reset) (set-current-module MAIN) (assert (testfact A in MAIN)) (assert (testfact B in MAIN)) (focus A B) Module B contains a rule that matches a fact from module MAIN (see the mark). After loading MAIN.clp and running this little program jess displays the following facts: -Result with the marked statement Jess (facts *) f-0 (MAIN::initial-fact) f-1 (MAIN::testfact A in MAIN) f-2 (MAIN::testfact B in MAIN) f-3 (A::testfact A in A) f-4 (A::testfact B in A) f-5 (MAIN::testfact A in B) f-6 (MAIN::testfact B in B) For a total of 7 facts. Jess f-5 and f-6 should not be facts in module MAIN but in module B. After removing that marked pattern from the rule ForB, facts are created as expected: -Result without the marked statement Jess (facts *) f-0 (MAIN::initial-fact) f-1 (MAIN::testfact A in MAIN) f-2 (MAIN::testfact B in MAIN) f-3 (A::testfact A in A) f-4 (A::testfact B in A) f-5 (B::testfact A in B) f-6 (B::testfact B in B) For a total of 7 facts. Jess Can anybody tell me what I am doing wrong here? Felix Felix Bachmann Carnegie Mellon Voice: +1 (412) 268 6194 Software Engineering Institute FAX: +1 (412) 268 5758 Pittsburgh, PA 15213 To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED]
Re: JESS: Strange behavior when using Jess modules
I think Felix H. Bachmann wrote: A few days ago I posted a question concerning the use of modules and so far I did not get any answer. Is there really no one who could help me to figure out what is wrong with the following example? Probably because many people didn't bother to read it the first time. A pet peeve of mine: as you can see below, your message is pretty much incomprehensible for those of us who use normal plaintext MUAs. If you're going to send HTML mail to a mailing list (or frankly, to anyone) you should either make sure ahead of time they're interested in receiving it, or check the send as both HTML and plaintext box in your MUA. But this time, I fired up Mozilla to read it, and so I can explain what you're seeing. There's nothing wrong at all; you may not understand the rules Jess uses for module lookup. They're explained in section 2.10.2 of the manual, or page 125 of JIA. Specifically, as applied to your example: when parsing a rule like this: (defrule A::forA (MAIN::initial-fact) = (assert (testfact A in A)) (assert (testfact B in A))) Jess has to decide what module testfact is in. The procedure is really simple: Jess looks in module A, and if the template is not there, Jess looks in MAIN. If it's not there, then it gets created in the current module. In your program, this is A, and there's no MAIN::testfact, so A::testfact is created and used on the rule's RHS. Now, when Jess parses this rule: (defrule B::forB (initial-fact) (MAIN::testfact B in MAIN) = (assert (testfact A in B)) (assert (testfact B in B))) when Jess sees the MAIN::testfact pattern, this implied deftemplate is created in MAIN. Now on the RHS, Jess follows the same search procedure as when parsing the rule A::forA, but now the deftemplate MAIN::testfact is found, so it is used, and no new testfact template is created in the current module. [ Original message below. ] I think Felix H. Bachmann wrote: ?xml version=1.0 ?html head title/title /head body div align=leftfont face=Times New Romanspan style=font-size:10ptHi,/span/font/div div align=leftfont face=Times New Romanspan style=font-size:10pta few days ago I posted a question concerning the use of modules and so far I did not get any answer.#160; Is there really no one who could help me to figure out what is wrong with the following example?/span/font/div div align=leftbr/ /div div align=leftfont face=Times New Romanspan style=font-size:10ptFelix/span/font/div div align=leftbr/ /div div align=leftfont face=Times New Romanspan style=font-size:10ptHere an interesting issue. (I hope)/span/font/div div align=leftbr/ font face=Times New Romanspan style=font-size:10ptAssume the rules are structured into 3 modules (MAIN, A, and B) which contain statements to assert ordered facts as shown in this example:/span/font/div div align=leftbr/ font face=Courier Newspan style=font-size:10pt;/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt; c:/jess/test/A.clp/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt;/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(defmodule A)/span/font/div div align=leftbr/ font face=Courier Newspan style=font-size:10pt(defrule forA/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(MAIN::initial-fact)/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt=gt;/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(assert (testfact A in A))/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(assert (testfact B in A)))/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt;/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt; c:/jess/test/B.clp/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt;/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(defmodule B)/span/font/div div align=leftbr/ font face=Courier Newspan style=font-size:10pt(defrule forB/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(initial-fact)/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(MAIN::testfact B in MAIN) ; lt; This causes the trouble/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt=gt;/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(assert (testfact A in B))/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt(assert (testfact B in B)))/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt;/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt; c:/jess/test/MAIN.clp/span/font/div div align=leftfont face=Courier Newspan style=font-size:10pt;/span/font/div div align=leftbr/ font face=Courier Newspan style=font-size:10pt(batch
RE: JESS: Subrules
I'm thinking that this isn't declarative programming but more of a procedural approach to problem solving. In declarative programming, theoretically anyway, each rule should be incrementally independent as much as possible. By putting the rules in a situation like that shown below usually shows that the solution is not declarative but procedural. If ruleA is true then check ruleB means that ruleB is dependent on ruleA. Rather the data of ruleB might have some data that is modified by ruleA, then that would be declarative. Maybe what you really want here is rule sets where a rule set is activated only during the firing of certain rules. Yes, I know: That isn't much different in practice but the thinking behind it is significantly different. SDG jco -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Judson, Ross Sent: Tuesday, August 26, 2003 10:10 AM To: [EMAIL PROTECTED] Subject: JESS: Subrules From the wish-list department: I'd sure like it if, in the action portion of a rule definition, I could define new rules. Sort of like this: (defrule i-am-a-rule (condition 1) (condition 2) = (defrule subrule-1 (condition) = (action)) (action) ) or (defrule subrule-2 extends i-am-a-rule (condition) = (action)) When you're dealing with a lot of rules, this kind of thing can really help set up more complex nested if-then-if-then type stuff. In addition, it would be cool (don't you love hearing that ;) if you could do this, instead of using salience: (defrule rule-3 (declare (overrides i-am-a-rule)) (condition) = (action)) The effect of that would be that for any given set of facts, if both rule-3 and i-am-a-rule are activated, rule-3 fires, eliminating the activation of i-am-a-rule. For a general and somewhat more specific rule that can match on the same set of facts, there is no way to avoid using salience to perform the discrimination, unless you break the matching up and use signaling facts. This is somewhat undesirable. RJ To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED] To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED]
Re: JESS: Subrules
I think Judson, Ross wrote: From the wish-list department: I'd sure like it if, in the action portion of a rule definition, I could define new rules. Sort of like this: (defrule i-am-a-rule (condition 1) (condition 2) = (defrule subrule-1 (condition) = (action)) (action) ) You can achieve a quite similar effect using modules, optionally including the auto-focus declaration. (defmodule A) (defrule A::i-am-a-rule (declare (auto-focus TRUE)) (condition 1) (condition 2) = (action)) (defrule A::subrule-1 (condition 3) = (action)) The rule subrule-1 won't fire unless the rule i-am-a-rule is satsfied and grabs the module focus for module A. When any rules in A that apply are through firing, focus returns to the previous module (or you can use return to return earlier.) Module A is thus very much like a complex, multi-rule daemon that runs whenever a set of conditions are met. I use a technique like this in JIA for the user-input module in the Tax-forms Advisor in Part 3, and the Hardware Diagnostic Assistant in Part 4. In addition, it would be cool (don't you love hearing that ;) if you could do this, instead of using salience: (defrule rule-3 (declare (overrides i-am-a-rule)) (condition) = (action)) Interesting. This could certainly solve some common difficulties, and you're right that it's less messy than the traditional alternatives. Thanks for writing. You're usually a source of very good ideas! - Ernest Friedman-Hill Distributed Systems ResearchPhone: (925) 294-2154 Sandia National LabsFAX: (925) 294-2234 PO Box 969, MS 9012 [EMAIL PROTECTED] Livermore, CA 94550 http://herzberg.ca.sandia.gov To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED]
