Consider first what it gains. It inflicts an isolated c5 pawn on Black and the capture 17...Nxe4 concedes a tempo to White's Queen.

Now consider all the things which this capture concedes to Black. 17 dxc5 loses a tempo for development. It opens the b file for Black's Rook. Black gains by far the more powerful minor piece. The White Queen will have to move again after ...Bb7, and that makes a second tempo lost.

The conclusion is that on balance the capture 17 dxc5? concedes almost the value of a pawn to Black.

Topalov's play which follows this offers a lesson in what happens when a player wants more than a draw from a position where he has little or no advantage, and attempts to start unsound attacks from it, attacks which are based upon positional advantage that is insufficient or non existent.

21 f3? disturbs the King side pawns without necessity. On 21 Nc4 Qg5 22 e4 makes way for Rg3. However that may allow Black to equalize and possibly for this reason Topalov avoids it.

23 g3? disturbs again the King side pawns without necessity. 23 Nf1 may be perfectly safe, but Topalov does not want perfect safety. He wants to play for a win.

After 25...Ba6 it is probably Black who stands better and White who should think of how to equalize, perhaps by 26 Nc4. Topalov does not want it. He plays to win by 26 Ra3. This is an absurd attempt to win from what is fact a disadvantageous position. It is getting serious now because he is playing to attack when he has not only no advantage but perhaps a slight disadvantage. This could easily increase Black's advantage first to a strong degree and then to a winning degree.

27 Nb3? may be the last mistake, persisting in attempting to win from a disadvantageous position. This may increase Black's advantage from a substantial one to a winning one. Topalov has finally gone too far attempting to extract a win from an equal position.

After 27 Nb3 is the move 27...Rc7 necessary?

Suppose that instead of defending the c5 pawn by 27...Rc7 Black offers White the c5 pawn by 27...e5.

This move begins an attack based upon positional advantage. Providing that the attack is not disproportionate to Black's degree of advantage, such an attack is sound and will probably succeed against any defence. In that case it will be therefore too then to save White's game.

On 27...e5 28 Nxc5 Rc7 29 b4 e4 White is in some trouble.

On 28 Qxc5 Qe6 29 e4 g5 30 g4 Bxe4! 31 fxe4 Qxg4+ 32 Kf1 Rd1 is mate.

The advance 30..f5! also begins an attack based upon positional advantage, but as White has been given time to play the moves 29 Nc4 and 30 e4, Black's advantage has become reduced. The attack is still sound providing it is not disproportionate, and in that case it will probably succeed against any defence. However it may now take Black greater trouble to win, if he can do it at all.

32.fxe4 was a blunder where 32.Re3 was probably best with some advantage to black (e.g., 32...exf3+ 33.Kg1 Qg5 34.Qc2 Rcd7 35.Re1 Rd3 36.Ne5 Re3 37.Rxe3 Qxe3 38.Qb3+ Qxb3 39.axb3 Rd1+ Rf1) but seemingly a draw.

It seems 36.Nc2 was slightly better than 36.Kh4 but white's position was already lost. Perhaps 36...Qd8+ was better than 36...g5+ and 40...Kh7 was better than 40...Kg7 with maybe a few other nits.

Not quite, the draw is not assured.

40...f2+ 41. Kf2 Rd2+ is quite a poser for White.

i) 42. Kg1 Rg2+ is an immediate disaster with discovered checks.

Assuming this line with 40.Rf1 (I left off the number), I disagree about 40...f2+ it is not a good move as it exchanges black's attacking f-pawn for one of white's poorly doubled b-pawns, helping white. After 41.Kxf2 Rd2+ the correct move for white is 42.Kd3 activating its king. From here the best black can do is 42...Rxb2 and the position is double-edged with equal chances. Instead of giving my own line here, the following is from Rybka 4.1 after finishing depth d=26 with a dead draw:

[+0.00] d=26 43.f6 Rxb3+ 44.Kd2 gxf6 45.Rxf6 Rb2+ 46.Ke3 Rxh2 47.Rg6+ Kh8 48.Ra6 Rb2 49.Rxh6+ Kg7 50.Rg6+ Kh7 51.Ra6 Rb7 52.g4 Rc7 53.g5 Bg2 54.Rh6+ Kg7 55.Rg6+ Kh7 56.Rh6+ Kg7 57.Rg6+ Kh7 58.Rh6+ (0:15:27) 97676kN

Personally, I like black's position better before 31.exf5 because of bishop versus knight in an open position. I think 31.exf5 was a dubious move as I stated before, where I would have seen and played 31.Nd2 instead. Rybka 4.1 agrees with this.

Your points about squandering the attacking 'f' pawn and d3 being the better square for the K to move to are well taken.

My motivation in pawn barter was that it would facilitate the promotion of the 'c' pawn. I attempted this but it is tough for Black to deny a draw as White is in good position to commandeer the 'perpetual' adjunct.

Yes. At the time I had my misgivings about Sofia, but among World Champions he is 'The Gentleman', to date.

The way he tolerated GK's poor conduct and gamesmanship in the New York Match without showing any cracks in etiquette was proof beyond all doubt that Vishy is a man of breeding first and WC later.

The worst thing i've read on Vishy is when Van Wely acused him of ... clicking his pen during the game .

And , according to the same source , he even cleared his throat while NOT on the move . SHOCKING !!! (the story is true , the dutchman actually gave such an interview , acusing everyone and their mother for everything , namely http://www.chessedelic.com/2008/09/... IMO such things speak much more about the author than his targets ...).

Few quotes : <I indicated in an interview with the Volkskrant last year that Anand commits all kinds of dirty tricks to get you off balance: he makes clicking sounds with his pen when it is your move, and strange sounds with his throat > , and

< Q : But are you influenced by it ? I mean, the idea that you consider Anand a dirty dog could have a negative influence on your game. Or a positive one instead ?