Half the variations which are calculated in a tournament game turn out to be completely superfluous. Unfortunately, no one knows in advance which half.
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[Event "rated untimed match"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "Soultanbeieff"]
[Black "Borodin"]
[Result "*"]
[Annotator "David Hayes"]
[BlackElo "0"]
[FEN "q4r1k/5p1p/p2pp2Q/1p2b3/8/2P2R2/P1P4P/6RK w - - 0 1"]
[SetUp "1"]
[TimeControl "0"]
[WhiteElo "0"]
1. Rg2 b4 ( { Black can try: } 1... Qxf3 2. Qxf8# ) 2. Qxh7+ Kxh7 3. Rh3# *