**Previous message:**nna@snd.edu.gr: "WSEAS ECE NEWSLETTER"**Maybe in reply to:**Ernst Murnleitner: "truth values if one variable is undefined?"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

Hello Ernst,

In our software, XmlMiner and XMLRule, which you can look at on

http://www.metarule.com we use a sort of tristate logic, although that

doesn't really sum it up. Degrees of truth are represented as values between

0 and 1 inclusive, and a "don't know" condition is coded as -1. All our

operators handle the -1 case through a truth table, and propogate the don't

know through the rule to the result. For example an "and" function

returns -1 if either input is unknown, an "or" function returns the other

input value if one of the inputs is unknown etc. For a "not" function if the

input is -1, so is the output. Any aggregation has to take care of don't

knows propogating through and respond accordingly. You can get more

information on our web site. I'd be interested to know who else uses this

system, we've used it for some time.

Best wishes,

Andy Edmonds, Scientio, Inc.

"Ernst Murnleitner" <mur@awite.de> wrote in message

news:a7mv5s$m63j7$1@ID-130107.news.dfncis.de...

*> Dear readers,
*

*>
*

*> I want to handle undefined variables, i.e. if a measurement ist not
*

*> available and thus the input value is invalid:
*

*>
*

*> In our software, we set a flag "invalid" to true, if the measurement is
*

not

*> available.
*

*> But there comes up the following question: How should the term with the
*

*> undefined variable be handled?
*

*> One possibility would be, to let the truth always be "0" of that sub-term,
*

*> e.g.:
*

*> IF A = a THEN ...
*

*> ####
*

*> Here, (A=a) = 0
*

*>
*

*> But how should NOT be handled then?
*

*>
*

*> IF (NOT(A=a)) THEN
*

*> #########
*

*> Here, (NOT(A=a)) would be "1"!
*

*>
*

*> Or should the complete subterm with the undefined variable be "0"? Hence,
*

*> NOT(A=a) would be "0".
*

*>
*

*> (To Invalidate the whole rule, Is not a good idea: because: IF A=a OR B=b
*

*> THEN ...)
*

*>
*

*> Greetings
*

*> Ernst Murnleitner
*

*>
*

*>
*

*>
*

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**Next message:**Simon Garrett: "CFP ICARIS-2002"**Previous message:**nna@snd.edu.gr: "WSEAS ECE NEWSLETTER"**Maybe in reply to:**Ernst Murnleitner: "truth values if one variable is undefined?"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]

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