Qq-rotations.cql

; Qq-rotations.cql can be downloaded here.

; Find games where a black and white Queen are separated by a single piece,
; and where all eight possible orientations of this configuration of queens occurs.
; Actually we games where at least 5 of the orientations occur, sorted by the number
; of orientations.
; 
; To understand this, suppose there is a Q on d4. Then right 1 Q is
; the square e4, and [Aa] on right 1 Q will match a position with the Q on d4, and a piece on e4.
; 
; Then right 1 [Aa] on right 1 Q will be the square f4, and so
; q on right 1 [Aa] on right 1 Q
; will match a position with the Q on d4, a piece on e4 and a q on f4. Since this works no matter
; where the Q is, this matches one of the eight orientations of the Q and q. Now when we put a rotate45
; in front of this, the "right" is replaced successively by northeast, north, southwest, and so on over all
; the directions. This gives us all the orientations.

cql(input heijden.pgn variations)
initial
 sort "Number of theme occurrences" rotate45 5 8
  next* q on right 1 [Aa] on right 1 Q