rookleapcorners.cql

// Download rookleapcorners.cql
// PGN output when run on sample.pgn

/* a white rook, starting on a corner square,
   visits the three other corners in exactly
   three moves. Moves by pieces other than this
   rook are ignored.
*/

cql(input hhdbvi.pgn)
T∊♖
 ✵⊢◎T
    a1――h1
      ――h8
      ――a8