Hi,
I'm new to JESS and I have a few question in the pump example (pump.clp) .
My questions might be too easy, but I'm learning JESS now. So..... :-)
1. (deftemplate machine (slot name) (slot class) (slot OBJECT))
I guess (slot OBJECT) is related to using JavaBeans, but it is not clear
when and how I can use it because some JavaBean object (Pump) used it, but
some others (Tank) did not use it.
2. From the rais-rate-if-low rule in the pump.clp
(defrule raise-rate-if-low
?warning <- (warning low ?name)
(pump (name ?name) (flow ?flow-rate) (OBJECT ?pump))
(test (< ?flow-rate 25))
(idle ?n)
?a <- (adjust-time ?t&:(< ?t (- ?n 20)))
=>
...)
Why do we need (OBJECT ?pump) in the second condition of LHS?
Why do we need (OBJECT ?*) only in the pump instance, not in the tank
instance?
For example, in the warn-if-low rule definition, tank instance did not have
this thing.
(defrule warn-if-low
(tank (name ?name) (low TRUE) (intact TRUE)) // did not use OBJECT
stuff here
...)
3. In the same raise-rate-if-low rule definition, if idle is '0', then what
is the value of '?a'?
Since (adjust-time ?t&:(< ?t (- ?n 20))) cannot be satisfied (?n = 0 in this
case), I think '?a' should not be a valid fact id. Therefore, this rule does
not fire and '?' is not important.
Is it correct?
4. In the notify-if-ok rule definition...
(defrule notify-if-ok
?warning <- (warning ? ?name)
--
....)
What is the first '?'? I guess it is a wildcard variable which can be
matched to anything, but I'm not sure.
Thanks in advance.
YJ
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