I think you didn't appreciate what Wolfgang is saying. A list -- and a
multislot is indeed a list -- is intrinsically ordered. The order in
which the items appear matters. If you have a collection in which the
order does not matter, then a list isn't appropriate to store it; it's
a set, not a list. To implement a set in Jess, you can use a
java.util.Set implementation in a regular slot. By doing this, all the
difficulties you describe just go away.
On Feb 24, 2009, at 8:40 AM, Joao Antunes Mourao wrote:
Thanks Wolfgang,
but i had solve already my problem.
My question was only about the duplication of /"nots/", that one has
to
write in order to not duplicate facts. I handle the situation
creating a
function that check if a list contains a specific element or set of
elements, without mind to the sequence.
Like for example you have a fact:
/(black-cars (id A B))/
and somewhere you have a rule that takes two cars, but then you
enforce
that the cars cannot be black, like:
/(defrule ...
(car (id ?id1))
(car (id ?id2))
(not (black-black-cars (id ?id1 ?id2))/
..
now, if the matching variables get: ?id1=B, and ?id2=A, then the rule
will be fired, and the only way to avoid this is having another "/
not/"
swaping the ids. This kind of solution becomes really confuse, if you
have a list of 3 or more elements. So, i implement a function that
check
if a list contains a set of elements. My question in the mailing list
was only wondering if there was a more clean way to make this. It
seems not.
Regards,
Joao
----------
unclassified
On 24-02-2009 09:39, Wolfgang Laun wrote:
Perhaps the discussion in
http://www.jessrules.com/jesswiki/view?PropertySet is useful for you.
-W
On Mon, Feb 23, 2009 at 6:11 PM, Wolfgang Laun
<[email protected] <mailto:[email protected]>> wrote:
On Mon, Feb 23, 2009 at 5:22 PM, Joao Antunes Mourao
<[email protected]
<mailto:[email protected]>> wrote:
Hello,
/(defrule get-black-cars
(car (id ?id1) (color "black"))
(car (id ?id2 &:(~= ?id1 ?id2)) (color "black"))
(and (not (black-cars (car-id ?id1 ?id2)) (not (black-cars
(car-id ?id2 ?id1)))
=>
(assert (black-cars (car-id ?id1 ?id2)))/
The second CE is better written as
(car (id ?id2 & ~?id1)) (color "black"))
My question is: There is a matching way of avoid this
comparison? The only thing i want to know is which are the
black cars, not the order.
You are talking of sets (in the mathematical sense). For the
general case you might consider using a java.util.Set as a
(non-multi-)slot value.
-W
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