如何在存在条件下正确使用加法？剪辑

Question

我正在检查车前是否有任何障碍物。假设汽车位于位置“2”。我的目标是检查位置“3”是否有障碍物。可能没有明确的障碍物事实，这意味着在那个特定位置没有任何障碍物。我检查使用 exists 条件。但是我在规则 r6 中的这部分 (+ ?location_car 1) 得到 CLIPS 语法错误 [PRNTUTIL2] 。如果我放弃添加，它会起作用。我可以使用什么替代方法，或者我只是缺少一些语法？

  (deftemplate car
  (slot location)
)
(deftemplate obstacles
  (slot location) ; location of road segment
  (slot tlights) ; number of red traffic lights
  (slot cars) ; number of cars which have priority drive through
  (slot pedestrians) ; number of pedestrians crossing the road
  (slot spec_service) ; number of spec service vehicles passing by
)

(deffacts faktu-inicializavimas
 (car (location 0))
 (obstacles (location 9) (tlights 1) (cars 2) (pedestrians 5) (spec_service 2))
)

(defrule r6 "Drive to location"
  ?fact-id1 <- (car (location ?location_car))
  (or
    (exists (obstacles (location (+ ?location_car 1)) (tlights 0) (cars 0) (pedestrians 0) (spec_service 0)))
    (not
      (exists (obstacles (location (+ ?location_car 1)) ))
    )
  )
=>
 (printout t "Drive to location")
 (modify ?fact-id1 (location (+ ?location_car 2)))
)

Answer 1

使用 return 值约束（等号 =）将字段约束为函数调用的 return 值。

(defrule r6 "Drive to location"
  ?fact-id1 <- (car (location ?location_car))
  (or
    (exists (obstacles (location =(+ ?location_car 1)) 
                       (tlights 0) 
                       (cars 0) 
                       (pedestrians 0) 
                       (spec_service 0)))
    (not
      (exists (obstacles (location =(+ ?location_car 1)) ))
    )
  )
=>
 (printout t "Drive to location")
 (modify ?fact-id1 (location (+ ?location_car 2)))
)

如何在存在条件下正确使用加法？剪辑

How to use addition correctly within exists conditional? CLIPS

exists

syntax-error

addition

clips