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