(defdomain freecell  (  ; The problem has three degrees of freedom: How many freecells are available,  ; how many cards are there, and how many columns of cards we have.  ;  ; State of the world is determined by these atoms:  ; (on ?s1 ?n1 ?s2 ?n2) : Card (?s1 ?n1) is on top of card (?s2 ?n2).  ; (in-cell ?s ?n) : Card (?s ?n) is in a freecell.  ; (empty-cols ?c) : ?c columns are empty.  ; (empty-cells ?c) : ?c freecells are available.  ; (done ?s ?n) : The last card in suit ?s we are done with is card (?s ?n).  ; ---------------------- Operators ----------------------    ; A bookkeeping operator, just to initialize the (done ?s ?n) predicate.    (:operator (!!done)               ()               ()               ((done s 0) (done h 0) (done d 0) (done c 0)) 0)    ; Move (?s1 ?n1) which is on top of (?s2 ?n2) onto top of (?s3 ?n3).    ; ?s2 or ?s3 can be nil exclusively.    (:operator (!move ?s1 ?n1 ?s3 ?n3)               ; Precondition               ((on ?s1 ?n1 ?s2 ?n2) (empty-cols ?c1))               ; Delete list               ((on ?s1 ?n1 ?s2 ?n2) (empty-cols ?c1)                (forall (?s4 ?n4) (forbidden ?s4 ?n4 ?s1 ?n1)                  ((forbidden ?s4 ?n4 ?s1 ?n1))))               ; Add list               ((on ?s1 ?n1 ?s3 ?n3) (forbidden ?s1 ?n1 ?s2 ?n2)                (empty-cols (call + ?c1                                    (call CheckNull ?s2 1)                                    (call CheckNull ?s3 -1)))))    ; Free (?s1 ?n1) which is on top of (?s2 ?n2).    ; ?s2 can be nil.    (:operator (!free ?s1 ?n1)               ; Precondition               ((empty-cells ?cell1) (on ?s1 ?n1 ?s2 ?n2) (empty-cols ?col1))               ; Delete list               ((on ?s1 ?n1 ?s2 ?n2) (empty-cells ?cell1) (empty-cols ?col1)                (forall (?s3 ?n3) (forbidden ?s3 ?n3 ?s1 ?n1)                  ((forbidden ?s3 ?n3 ?s1 ?n1))))               ; Add list               ((in-cell ?s1 ?n1) (forbidden ?s1 ?n1 ?s2 ?n2)                (empty-cells (call - ?cell1 1))                (empty-cols (call + ?col1 (call CheckNull ?s2 1)))))    ; Move (?s1 ?n1) from a cell onto top of (?s2 ?n2).    ; ?s2 can be nil.    (:operator (!unfree ?s1 ?n1 ?s2 ?n2)               ; Precondition               ((empty-cells ?cell1) (empty-cols ?col1))               ; Delete list               ((in-cell ?s1 ?n1) (empty-cells ?cell1) (empty-cols ?col1))               ; Add list               ((on ?s1 ?n1 ?s2 ?n2) (forbidden dummy dummy ?s1 ?n1)                (empty-cells (call + ?cell1 1))                (empty-cols (call + ?col1 (call CheckNull ?s2 -1)))))    ; Finish (?s1 ?n1) which is on top of (?s2 ?n2).    ; ?s2 can be nil.    (:operator (!finish ?s1 ?n1)               ; Precondition               ((on ?s1 ?n1 ?s2 ?n2) (empty-cols ?col1))               ; Delete list               ((on ?s1 ?n1 ?s2 ?n2) (done ?s1 (call - ?n1 1))                (empty-cols ?col1)                (forall (?x ?y ?z ?t) (forbidden ?x ?y ?z ?t)                  ((forbidden ?x ?y ?z ?t))))               ; Add list               ((done ?s1 ?n1) (empty-cols (call + ?col1                                                   (call CheckNull ?s2 1)))))    ; Finish (?s1 ?n1) from a freecell.    (:operator (!finish-from-cell ?s1 ?n1)               ; Precondition               ((empty-cells ?c1))               ; Delete list               ((in-cell ?s1 ?n1) (done ?s1 (call - ?n1 1)) (empty-cells ?c1)                (forall (?x ?y ?z ?t) (forbidden ?x ?y ?z ?t)                  ((forbidden ?x ?y ?z ?t))))               ; Add list               ((done ?s1 ?n1) (empty-cells (call + ?c1 1))))  ; ----------------------- Methods -----------------------    ; Get (?s1 ?n1) out of the way by finishing it.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-finish             ((done ?s1 ?n2) (call = (call + ?n2 1) ?n1))             ((!finish ?s1 ?n1)))    ; Get (?s1 ?n1) out of the way by moving it to another column.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-move             ((movable ?s1 ?n1 ?s2 ?n2))             ((!move ?s1 ?n1 ?s2 ?n2)))    ; Get (?s1 ?n1) out of the way by moving it to an empty column.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-col             ((not (forbidden ?s1 ?n1 nil nil)) (empty-cols ?c) (call > ?c 0))             ((!move ?s1 ?n1 nil nil)))    ; Get (?s1 ?n1) out of the way by moving it to a freecell.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-cell             ((not (forbidden dummy dummy ?s1 ?n1)) (empty-cells ?c)              (call > ?c 0))             ((!free ?s1 ?n1)))    ; Try to get (?s1 ?n1) out of the way by finishing another card.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-other-finish             ((done ?s2 ?n3) (call = (call + ?n3 1) ?n2)              (not (on ?s4 ?n4 ?s2 ?n2)))             ((!finish ?s2 ?n2)              (:immediate bottom-out-of-the-way ?s1 ?n1)))    ; Try to get (?s1 ?n1) out of the way by finishing another card in a    ; freecell.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-other-finish-cell             ((in-cell ?s2 ?n2) (done ?s2 ?n3) (call = (call + ?n3 1) ?n2))             ((!finish-from-cell ?s2 ?n2)              (:immediate bottom-out-of-the-way ?s1 ?n1)))    ; Try to get (?s1 ?n1) out of the way by moving another card in a freecell    ; onto top of a column.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-other-unfree             ((in-cell ?s2 ?n2) (movable ?s2 ?n2 ?s3 ?n3)              (call != (?s3 ?n3) (?s1 ?n1)))             ((!unfree ?s2 ?n2 ?s3 ?n3)              (:immediate bottom-out-of-the-way ?s1 ?n1)))    ; Try to get (?s1 ?n1) out of the way by moving another crad in a freecell    ; to an empty column.    (:method (bottom-out-of-the-way ?s1 ?n1)             bottom-out-of-the-way-other-unfree-col             ((in-cell ?s2 ?n2) (not (forbidden ?s2 ?n2 nil nil))              (empty-cols ?c) (call > ?c 0))             ((!unfree ?s2 ?n2 nil nil)              (:immediate bottom-out-of-the-way ?s1 ?n1)))    ; Get (?s1 ?n1) out of the way of (?s2 ?n2).    (:method (out-of-the-way ?s1 ?n1 ?s2 ?n2)             ; If it is already got out of the way, do nothing.             (not (on-top ?s1 ?n1 ?s2 ?n2))             nil             ; First get rid of the other cards in the way.             (on ?s3 ?n3 ?s1 ?n1)             ((out-of-the-way ?s3 ?n3 ?s1 ?n1)              (:immediate out-of-the-way ?s1 ?n1 ?s2 ?n2))             ; If it is the bottom card, get it out of the way directly.             nil             ((bottom-out-of-the-way ?s1 ?n1)))    ; Top-layer task: Finish (?s1 ?n1).    (:method (do-card ?s1 ?n1)             ; Do nothing if it is already finished.             ((done ?s1 ?n2) (call <= ?n1 ?n2))             nil             ; Finish it if it is in a freecell.             (in-cell ?s1 ?n1)             ((!finish-from-cell ?s1 ?n1))             ; If there are other cards in the way, get rid of them.             (on ?s2 ?n2 ?s1 ?n1)             ((out-of-the-way ?s2 ?n2 ?s1 ?n1) (:immediate !finish ?s1 ?n1))             ; If it is in the bottom of a column, finish it.             nil             ((!finish ?s1 ?n1)))  ; ------------------------ Axioms -----------------------    ; Different colors    (:- (diff-clr s h) nil)    (:- (diff-clr s d) nil)    (:- (diff-clr h s) nil)    (:- (diff-clr h c) nil)    (:- (diff-clr d s) nil)    (:- (diff-clr d c) nil)    (:- (diff-clr c h) nil)    (:- (diff-clr c d) nil)    ; Can (?s1 ?n1) be moved onto top of (?s2 ?n2)?    (:- (movable ?s1 ?n1 ?s2 ?n2)        ((assign ?n2 (call + ?n1 1)) (diff-clr ?s1 ?s2) (on ?s2 ?n2 ?s3 ?n3)         (not (on ?s4 ?n4 ?s2 ?n2)) (not (forbidden ?s1 ?n1 ?s2 ?n2))))    ; Is (?s1 ?n1), directly or indirectly, on top of (?s2 ?n2)?    (:- (on-top ?s1 ?n1 ?s2 ?n2)        (on ?s1 ?n1 ?s2 ?n2)        ((on ?s1 ?n1 ?s3 ?n3) (on-top ?s3 ?n3 ?s2 ?n2)))))