Hi everybody,
I am a new user of JESS and I am coming from Prolog's world, so I have some
misunderstanding using Jess. First of all, I am trying to create a plan that
I will have 3 actions: travel, hotel and rentalCar. As I have some
preconditions that must be valid in order to execute an action, I want to
estabilish a first order. I have only 3 actions because I am trying to
understand Jess, so I need to know what exactly they are doing. How can I do
the prolog's trace in Jess? Because he shows me only the steps and the
result, but if I want to do step by step. I tried to create a batch file,
here it is:
(reset)
(assert (in paris) (passportValid paris salvador))
(defrule travel "Travel"
(in paris)
(passportValid paris salvador)
=>
(printout t "Travel service" crlf)
(assert (in salvador) (travel ok) (airportArea salvador
laurofreitas))
)
(defrule hotel "Hotel"
(in salvador)
(travel ok)
=>
(printout t "Hotel service" crlf)
(assert (hotel ok))
)
(defrule rentalcar "Rental a car"
(in salvador)
(travel ok)
(hotel ok)
(airportArea salvador laurofreitas)
=>
(printout t "Rental Car service" crlf)
(assert (car ok))
)
(defrule goal "Aim the goal"
(travel ok)
(hotel ok)
(car ok)
=>
(printout t "End of the plan" crlf)
)
(run)
When I run it, I receive this answer:
Jess> (batch Z:/Implementacao/planning/travel.clp)
==> f-0 (MAIN::initial-fact)
==> f-1 (MAIN::in paris)
==> f-2 (MAIN::passportValid paris salvador)
Travel service
==> f-3 (MAIN::in salvador)
==> f-4 (MAIN::travel ok)
==> f-5 (MAIN::airportArea salvador laurofreitas)
==> f-6 (MAIN::hotel ok)
Rental Car service
==> f-7 (MAIN::car ok)
End of the plan
Hotel service
5
The first thing that I do not understand was why it writes "Hotel service"
at the end if it was executed in the middle as we can see f-6
The next question, I have read about Jess but actually I do not understand
what is exactly the best use for deftemplates? I know it is like
classes/objects in Java, but in an inference motor where should I use it? In
my example here, I thought that I could use, but actually I did not find
where I can put it.
Thanks in advance for all your help.
Daniela
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