An html version of Prokes.cql which is not in the file.

Created by Gady Costeff.

CQL 5.1
; adjacent rank-2 black pawns attack a white rook, ; which sacrifices itself next to the black King, allowing ; the white king to take one of the pawns cql(input heijden.pgn result 1-0) piece $pawn1 in pa-h2 piece $pawn2 in pa-h2 on not $pawn1 attacks (K $pawn1) piece $rook in Ra-h1 attacks($pawn2 $rook) next( move from $rook {check move from k to $rook} move from K to $pawn1 )

CQL 3.2
; The Prokes manoeuvre is a square-vacating anti-promotion combination
 :pgn heijden.pgn
 :output Prokes.pgn
(position Kd2 pc2 pb2 Ra1 k[a-h4] :moveto .a4 :movefrom Ra1 :attackcount a .a4 1 10
:flipcolor :shifthorizontal :flipvertical)
After executing this with "> cql Prokes.cql" there are 9 studies found in the Harold van der Heijden Database 2015.
NB. When you see {MATCH} in the text, it means that cql has found the position asked for.

Below only 4 studies presented: