* (gps '(son-at-home car-needs-battery have-money have-phone-book) '(son-at-school) *school-ops*) (EXECUTING LOOK-UP-NUMBER) (EXECUTING TELEPHONE-SHOP) (EXECUTING TELL-SHOP-PROBLEM) (EXECUTING GIVE-SHOP-MONEY) (EXECUTING SHOP-INSTALLS-BATTERY) (EXECUTING DRIVE-SON-TO-SCHOOL) SOLVED * (gps '(son-at-home car-needs-battery) '(son-at-school) *school-ops*) NIL * (gps '(son-at-home car-works) '(son-at-school) *school-ops*) (EXECUTING DRIVE-SON-TO-SCHOOL) SOLVED