GM Alexandra Kosteniuk (SUI, 2495) vs IM Deysi Cori T. (PER, 2316) · 1-0
Board 1, Switzerland vs Peru, women’s event · French Defence, Classical Variation, Shirov-Anand System (C11) · 90 minutes for 40 moves, then 30 minutes, plus 30 seconds per move
By Bogner AI Coach AI Coach . This analysis was written by a Bogner Chess AI coach.
Round eleven, the last round of the women’s event, board one, Switzerland against Peru. GM Alexandra Kosteniuk sits with White across from Peruvian IM Deysi Cori, a player who has belonged to Peru’s Olympiad squad for more than ten years. On the last day of an Olympiad, what stands on paper counts less and what is made on the board counts more. For the team the whole thing is the top-board point.
Out of a French Defence, Classical, Shirov-Anand Variation, the usual small white edge emerges. On move seventeen Cori is offered a clean equaliser and does not find it. From there White takes not the shortest road, but the right one, and on move thirty the bishop goes to h6, the second time in this Olympiad.
The knight’s road: 5.Nce2 to 16.Nb5
is the core of the Shirov-Anand Variation against the Classical French. The knight moves from c3 to e2 so that c3 and d4 can support the central pawn on e5, and later it returns to its old square. From there it aims either at d5 or, as here, at b5 with a tempo against the b4 bishop, who came out with as a checker and then stayed there.
Kosteniuk plays the book moves through cleanly. is a note quieter than but hands nothing essential away, and with the question is on the board that the whole game will turn on: what does the black bishop on b4 do? Leaving it there costs a tempo, taking it back costs the black pawn structure.
The rule in the French setup: a knight that voluntarily walks to the edge must keep the way back to the centre open. The detour c3-e2-c3-b5 earns its price only when it ends on a square that has something to say to an opposing piece.
IM Deysi Cori T. (PER, 2316)
GM Alexandra Kosteniuk (SUI, 2495)
The tactical error: 17...h6
has, together with and , put the question to the black bishop on b4 for a third time. The move that equalises is , with the white king exposed, the c6 knight entering via d4, everything fluid. Not a pretty equaliser, but a fully honest one for Black.
The game saw . This is a tactical error, not an inaccuracy in move order: the h6 pawn changes the king’s shell permanently without answering the question about the bishop, and it opens the c1-h6 diagonal for the white bishop on d2, which suddenly has a target. The evaluation jumps by roughly a pawn and a half to White, and from here Black stands clearly worse.
The rule: a weakening move around your own king is only fine when it stops a concrete enemy plan. When the question on the board is “trade bishops or not”, the answer is “trade”, before anything is touched near the king.
IM Deysi Cori T. (PER, 2316)
GM Alexandra Kosteniuk (SUI, 2495)
The long think: 18.Rc1
White has been given the mistake and now has to convert it. The objectively best move repeats twice: and . After two pawns are gone and the black king stands open; that is about half a pawn more than what the game gave.
Kosteniuk thinks here for fifteen minutes and thirty-three seconds. She has one hour and three minutes left afterwards, she is not in time trouble. The game saw . The move develops the last rook, keeps the pressure on the b4 bishop and holds the advantage, but it is not the combination. On the next move White again passed on Bxb4 and played ; then Black herself moved the bishop out of the line of fire with . The advantage dropped by roughly half a pawn and stayed clear anyway.
is a human choice. A player who has not carried the calculation to the end after fifteen minutes will rather play the move that spoils nothing. Objectively it is still the wrong one. The rule: when the same exchange is best two moves in a row, it is usually a real win, not a matter of taste. Calculate the forcing move first, the useful one waits.
IM Deysi Cori T. (PER, 2316)
GM Alexandra Kosteniuk (SUI, 2495)
The move that turned it: 30.Bxh6
Between move twenty and move thirty the clock ran away from Black. From sixteen minutes after move twenty, fifty-six seconds were left after move thirty; from move twenty-six on Cori was under five minutes, from move twenty-nine on under one minute. Kosteniuk went from one hour to forty-two minutes in the same span, her time was never in danger, and her two longest thinks were behind her, on and .
The attack stood ready on the board: rook h4, rook g3, knight e5, queen e2, bishop d2. On the black side only the g7 pawn defended the h6 pawn. takes the pawn and offers the bishop up. The point is the rook on g3: it pins the g7 pawn to its own king, gxh6 is not legal. Black has no other defenders of h6, the bishops on e8 and f8 do not reach the square, the rook on f6 has no path to the h file.
The game continued , and Black stood down the exchange and a pawn; Cori resigned here. The rule of the square: a pawn defends an attacked square only as long as it is allowed to move. Before a sacrifice near the king, count your own rook on the pin line.
IM Deysi Cori T. (PER, 2316)
GM Alexandra Kosteniuk (SUI, 2495)
Verdict
A full point on board one in the closing round, against an experienced Peruvian, on a seventeenth-move error by the opponent and a conversion that passed the short road twice and arrived in the end anyway. For the team it is the top-board point that a tight team match needs. For Kosteniuk it is the second full point of this Olympiad after round nine, and the lesson to check the forcing move before the useful one is the same one as in round six.
Moves
1-0
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