George Duke wrote on Sat, Sep 1, 2012 10:43 PM UTC:
Karpov was world chess champion 1975-1985.
Http://www.chessvariants.org/index/displaycomment.php?commentid=29431,
there is a game, the first to consider, in the 1985 Karpov-Kasparov match,
but Karpov has better move sequence from Move 30 on, as noted where White goes wrong.
The spectacular finish requires that mistake '30 ...f3' actually done, but White can take the game in a different direction, not ending at Move 40, with 30 ...g4.
