An html version of Grimshaw.cql. Created by Peter Boll.

;search for Grimshaw interferences:
;; Grimshaw. An interference with two black pieces arriving on a particular square mutually interfere with each other.
; we look for 4 kind of postions. With two rooks interfering each other; With two queens interfering each other
; with two bishops interfering each other and with a queen and a bishop interfering each other.
(match :pgn heijden.pgn :output Grimshaw.pgn (position :moveto .b2 :wtm :and ((position :sequence ((position :moveto .b2) (position :movefrom r :moveto Ab2))) (position :sequence ((position :moveto .b2) (position :movefrom r :moveto Ab2))) ) :shift :markall :variations ) (position :moveto .b2 :wtm :and ((position :sequence ((position :moveto .b2) (position :movefrom q :moveto Ab2))) (position :sequence ((position :moveto .b2) (position :movefrom q :moveto Ab2))) ) :shift :markall :variations ) (position :moveto .b2 :wtm :and ((position :sequence ((position :moveto .b2) (position :movefrom b :moveto Ab2))) (position :sequence ((position :moveto .b2) (position :movefrom b :moveto Ab2))) ) :shift :markall :variations ) (position :moveto .b2 :wtm :and ((position :sequence ((position :moveto .b2) (position :movefrom b :moveto Ab2))) (position :sequence ((position :moveto .b2) (position :movefrom q :moveto Ab2))) ) :shift :markall :variations ) )

After executing this with "> cql Grimshaw.cql" there are 53 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 5 studies are presented: