Debasish,
If you want to create an explicit template, it should look like this:
(deftemplate MAIN::opposite-of
(slot entity-A)
(slot entity-B))
Then the facts would be declared as:
(opposite-of (entity-A shore-1) (entity-B shore-2))
However, you'd also have to assert
(opposite-of (entity-A shore-2) (entity-B shore-1))
This will lead to problems with rules firing twice, once on each opposite-of
assertion. To handle that, you can adopt a convention that all commutative
relations, such as opposite-of, are expressed with arguments in canonical
order (e.g., sorted alphabetically):
(deftemplate MAIN::canonical-opposite-of
(multislot entities))
This will result in facts of the form
(canonical-opposite-of (entities shore-1 shore-2))
you will have to make sure that facts of the form
(canonical-opposite-of (entities shore-2 shore-1)) ;;NOT CANONICAL
are never asserted. Also, when you assert a fact you'll to make sure that
the arguments are sorted in the right order (e.g., by applying a
deffunction).
Hope this helps.
-John
From: debasish.da...@cognizant.com [mailto:debasish.da...@cognizant.com]
Sent: Monday, November 22, 2010 3:38 AM
To: jess-users@sandia.gov
Subject: JESS: representation of deftemplate from deffacts
Hi Jess-users,
Just trying to understand, how the following deffacts can represent in
deftemplate?
(deffacts MAIN::opposites
(opposite-of shore-1 shore-2)
(opposite-of shore-2 shore-1))
Jess is creating a *implied* template for this as below.
(deftemplate MAIN::opposite-of
"(Implied)"
(multislot __data))
Here the term *__data* is not very much clear, since if I keep this as
template explicitly as follows -
(deftemplate MAIN::opposite-of
(multislot __data))
The ruleset is running fine as expected, and JESS is not creating again the
*implied* template in this case. But, if I change it to some other name, say
*data* instead of *__data*, JESS engine throwing a exception (Jess reported
an error in routine Jesp.parseFact.)while parsing the above fact.
Also, if I create the template as follows using *slot*.
(deftemplate MAIN::opposite-of
(slot shore-1)
(slot shore-2))
But in this case, the deffacts needs to be defined as follows, which seems
not same as mentioned above, and the rule is not working as expected.
(deffacts MAIN::opposites
(opposite-of (shore-1 shore-2))
(opposite-of (shore-2 shore-1)))
OR
(deffacts MAIN::initial-opposite-of
(opposite-of (shore-1 shore-2)
(shore-2 shore-1)))
So, if anyone can clarify this.
Regards
DEBASISH DALUI (122816)
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