;;;======================================================
;;;   Weather Prediction Expert System for London
;;;
;;;     
;;;
;;;     FuzzyCLIPS Version 6.0 Example
;;; 
;;;     To execute, merely load, reset, and run.
;;;======================================================

(defrule rainrainrule 
	"if it is raining it is likely to continue raining" 
	(declare (cf .5))   ; certainty factor for rule is .5
	(today rain) 
	=>
	(assert (tomorrow rain))
)

(defrule drydryrule 
	"if it is dry it is likely to continue being dry" 
	(declare (cf .5))   ; certainty factor for rule is .5
	(today dry) 
	=>
	(assert (tomorrow dry))
)


(defrule rainclearingrule 
	"if it is raining but not much, maybe it is clearing " 
	(declare (cf .6))    
	(today rain) 
	(rain low)
	=>
	(assert (tomorrow dry))
)

(defrule raincoldclearingrule 
	"if it is raining but not much, and it is cold out, maybe it is clearing " 
	(declare (cf .7))    
	(today rain) 
	(rain low)
	(temp cold)
	=>
	(assert (tomorrow dry))
)


(defrule dryrainrule 
	"if it is dry but temperature is warm - maybe we'll get rain" 
	(declare (cf .65))    
	(today dry) 
	(temp warm)
	=>
	(assert (tomorrow rain))
)


(defrule dryovercastrainrule 
	"if it is dry but temperature is warm and sky is overcast - maybe we'll get rain" 
	(declare (cf .55))    ;; not sure why this is less certain than previous
	(today dry) 
	(temp warm)
	(sky overcast)
	=>
	(assert (tomorrow rain))
)


(defrule combineEvidenceRule
	" combine evidence reaching the same conclusion"
	?f1 <- (tomorrow ?answ)
	?f2 <- (tomorrow ?answ)   ;;; same answer
	(test (not (eq ?f1 ?f2)))
	=>
	;;(if (not (eq ?f1 f2))
	;;then 
	(printout t "facts " ?f1 " " ?f2 t)
	(bind ?cf1 (get-cf ?f1))
	(bind ?cf2 (get-cf ?f2))
	(printout t "one minus " (- 1 ?cf1) t)
	(printout t "times " (* ?cf2 (- 1 ?cf1)) t)
	(printout t "revised " (+ ?cf1 (* ?cf2 (- 1 ?cf1))) t)
	(bind ?newcf (+ ?cf1 (* ?cf2 (- 1 ?cf1))))
	(retract ?f1)
	(retract ?f2)
   (disable-rule-cf-calculation) ;; turn off rule cf calculations
	(assert (tomorrow ?answ) cf ?newcf)
   (enable-rule-cf-calculation) ;; turn back on again

	;;) ;; end if
)

(defrule answerrule
	" specify the answer with certainty factor"
	?f <- (tomorrow ?answ)
	=>
	(printout t t " The prediction is " ?answ " with certainty factor " (get-cf ?f) t )
)