An html version of kozirev2.cql
; kozirev2.cql can be downloaded here.
; This CQL file illustrates another way to search for echoes (shifted or flipped) in which there is some "give"
; that is, it is not a perfect echo.
; The motivation for this example was to search for
; studies similar to the beautiful 1995 study by Kozirev in which a stalemate configuration with
; Kd1, Bd2, kd3, bd4 and Qe5
; recurs rotated 90 degrees but without a pawn elsewhere on the board
;
; To do this we limit the search to non-pawn pieces
; Find games in which there are two
; positions P1 and P2, such that P2 is reached by a flip or transform from P1
; with the same side to move, such that P1 is a stalemate,
; at most 1 non-empty square is the same
; among the non-pawn pieces of P1 and P2
(match
; :pgn kozirev.pgn
:pgn heijden.pgn
:output out.pgn
(position
:stalemate
:markall
:piececount [KkRrQqNnBb] 4 100 ; Make sure the position is reasonably interesting
[KkRrQqNnBb] ; the pattern
:relation (:shift ; allow shifts
:pattern ; ignore pawns
:samesidetomove ; same side to move in P1 and P2
:originalsamecount 0 1 ; P1 and P2 cannot coincide in more than 2 nonempty squares
:flip) ; allow flips
:variations ; search in variations
)
)