staircase.cql

; staircase.cql can be downloaded here.

; Queen staircase of length at least 
; To understand this, first note that "Q"
; is the square a Q is on. So e.g. in the chess initial position,
; "Q" means "d1".
; Now, "up 1 Q" is one square up from that square, so it would be
; "d2" in the chess initial position.
; Thus, "move from Q to up 1 Q" means: move the Q up one square.
; The "move from Q to right 1 Q" means: move the Q right one square.
; So the basic next just looks for a length four staircase starting in the
; up direction, then going right, then up.
; The flip makes this look for any directions, and the flipcolor for any color.

cql(input heijden.pgn)

flipcolor flip 
 next (
        move from Q to up 1 Q
        btm
	move from Q to right 1 Q
	btm
	move from Q to up 1 Q
	btm
	move from Q to right 1 Q
      )