|g15713: White to move at 74
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According to FinalGen, a chess endgame tablebase generator for Windows, one now knows this is a win for White. Those with Lomonosov Endgame Tablebases for 7 pieces can verify this.
The following is an article on this endgame from ChessPublishing by Poghosyan - a great endgame specialist especially on rook endings!
Start with diagram D. 1 - the reading will make more sense
<"The structure a- and h-pawns versus h-pawn is generally favourable for the defender because losing the pawn does not lead automatically to a lost position. Liquidation to a drawn position without a pawn is often the only drawing strategy achieving a Vancura-type draw."> Poghosyan
<"This move throws away the win. White should have immediately activated his rook placing it behind his pawn.
74.Rd4+ Kf5 75.Ra4 Ra6. This position arose later in the game after 83…Kf5."> Poghosyan
White forgot Tarrasch's rule:
<"The original quote, from page 57 of his book The Game of Chess (1938) is:
In complicated Rook endings the most important rule is one laid down by the author: The Rook's place is behind the passed pawn; behind the enemy pawn in order to hold it up, behind one's own in order to support its advance.">