(def world3
  '#{(connects A1 A2)
     (connects A2 A1)
     (connects A2 A3)
     (connects A3 A2)
     (connects B1 B2)
     (connects B2 B3)
     (connects B3 B2)
     (connects B2 B1)
     (above B1 A3)
     (above C1 B3)
     (on ball C1)
     (on ball2 B2)
     (platform B1)
     (platform B2)
     (platform B3)
     (platform C1)
     (climbable B1)
     (climbable C1)
     (manipulable ball)
     (manipulable ball2)
     (agent R)
     })

(def state3
  '#{(at R A1)
     (holds R nil) ;Would just return nil without this
     })

(def ops3
  '{climb-on {:pre ((agent ?agent)      ; FIRST VERSION OF CLIMB ON
                     (at ?agent ?place)
                     (above ?platform ?place)
                     (climbable ?platform)
                     (holds ?agent nil)) ;This came later when we thought about the platform problem

              :del ((at ?agent ?place))
              :add ((at ?agent ?platform))
              :txt (climb on ?platform)
              :cmd [on ?agent ?platform]
              }

    pick-off {:pre ((agent ?agent)
                     (manipulable ?obj)
                     (platform ?platform)
                     (at ?agent ?platform)
                     (on ?obj ?platform)
                     (holds ?agent nil))

              :add ((holds ?agent ?obj))
              :del ((on ?obj ?platform)
                     (holds ?agent nil))
              :txt ((Pick off ?obj from ?platform))
              :cmd [Pick-off ?obj from ?platform]
              }


    move     {:pre ((agent ?agent)
                     (at ?agent ?p1)
                     (connects ?p1 ?p2))

              :add ((at ?agent ?p2))
              :del ((at ?agent ?p1))
              :txt ((move from ?p1 to ?p2))
              :cmd [move ?p1 to ?p2]
              }

    climb-off {:pre ((agent ?agent)
                      (at ?agent ?platform)
                      (above ?platform ?place)
                      (holds ?agent nil))
               :del ((at ?agent ?platform))
               :add ((at ?agent ?place))
               :txt (climb-off from ?platform)
               :cmd [climb-off from ?platform]
               }

    drop-on {:pre  ((agent ?agent)
                     (platform ?platform)
                     (at ?agent ?platform)
                     (:not (holds ?agent nil))
                     (holds ?agent ?obj))

             :add ((holds ?agent nil)
                    (on ?obj ?platform))
             :del ((holds ?agent ?obj))
             :txt ((drop-on ?obj on ?platform))
             :cmd [drop-on ?obj ?platform]
             }

    drop-from-platform {:pre  ((agent ?agent)
                                (platform ?platform)
                                (at ?agent ?platform)
                                (above ?platform ?place)
                                (:not (holds ?agent nil))
                                (holds ?agent ?obj))
                        :add ((holds ?agent nil)
                               (on ?obj ?place))
                        :del ((holds ?agent ?obj))
                        :txt ((Drop-from ?obj to ?place))
                        :cmd [drop-from ?obj to ?place]
                        }


    drop     {:pre ((agent ?agent)
                     (at ?agent ?place)
                     (:not (holds ?agent nil)) ;Agent would drop object "?obj" when holding nil so this line works around that
                     (holds ?agent ?obj))

              :add ((holds ?agent nil)
                     (on ?obj ?place))
              :del ((holds ?agent ?obj))
              :txt ((Drop ?obj at ?place))
              :cmd [drop ?obj at ?place]
              }

    pickup   {:pre ((agent ?agent)
                     (manipulable ?obj)
                     (at ?agent ?place)
                     (on ?obj ?place)
                     (holds ?agent nil))

              :add ((holds ?agent ?obj))
              :del ((on ?obj ?place)
                     (holds ?agent nil))
              :txt ((pickup ?obj at ?place))
              :cmd [pickup ?obj from ?place]
              }
    })


; (ops-search state3 '((at R A1)(holds R ball)) ops3 :world world3)
; (ops-search state3 '((at R A2) (on ball B2) (holds R nil)) ops3 :world world3)
; (ops-search state3 '((at R A2) (on ball B2) (on ball2 A3) (holds R nil)) ops3 :world world3)