Part of a rule-based system I am developing compares
data values to thresholds and outputs a warning if any
data value in a data set exceeds its threshold.
This is encapsulated in the notify-only rule below.
The requirements were then changed to include which
data values in a data set exceeded their thresholds.
This resulted in the notify-with-reason rule below.
Is this an appropriate use of the 'if' function?
I read in Giarratano & Riley that 'if' and 'while'
should be used judiciously.
One problem I see with notify-with-reason is data
values are compared to their thresholds twice.
Any suggestions on reworking this rule?
I should note that the deftemplate and defrule
commands are generated at runtime based on what
options a user selects, so data sets can vary
between runs of the system.
I am using Jess 6.0.
Thanks,
John
(deftemplate thresholds
(slot RPM)
(slot Temperature)
(slot Pressure))
(deftemplate data-set
(slot RPM)
(slot Temperature)
(slot Pressure))
(defrule notify-only
(thresholds (RPM ?RPM-threshold)
(Temperature ?Temperature-threshold)
(Pressure ?Pressure-threshold))
(data-set (RPM ?RPM-value)
(Temperature ?Temperature-value)
(Pressure ?Pressure-value))
(test (or (> ?RPM-value ?RPM-threshold)
(> ?Temperature-value ?Temperature-threshold)
(> ?Pressure-value ?Pressure-threshold)))
=>
(printout t "THRESHOLD EXCEEDED" crlf))
(defrule notify-with-reason
(thresholds (RPM ?RPM-threshold)
(Temperature ?Temperature-threshold)
(Pressure ?Pressure-threshold))
(data-set (RPM ?RPM-value)
(Temperature ?Temperature-value)
(Pressure ?Pressure-value))
(test (or (> ?RPM-value ?RPM-threshold)
(> ?Temperature-value ?Temperature-threshold)
(> ?Pressure-value ?Pressure-threshold)))
=>
(bind ?reason-code 0)
(if (> ?RPM-value ?RPM-threshold)
then (bind ?reason-code (bit-or ?reason-code 1)))
(if (> ?Temperature-value ?Temperature-threshold)
then (bind ?reason-code (bit-or ?reason-code 2)))
(if (> ?Pressure-value ?Pressure-threshold)
then (bind ?reason-code (bit-or ?reason-code 4)))
(printout t "THRESHOLD EXCEEDED, REASON CODE IS " ?reason-code crlf))
(reset)
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