KomodoDragon brilliancy Ruy Lopez - Marshall! A marshall reborn?

[Nay Lin Tun]

Prabably 21. Bf3? was the blunder as suggested my droidfish running 10-15 seconds per position.

Maybe there are other alternatives but I think 21.Bf3 move doens't deserve a "?" tag because it is also a strong move.

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29/45  +0.21  Qe1 Bf5 Bf3 Rg8 Re5 Bh3 Nf1 Qg7 Ng3 fxg3 hxg3 Bxe5 Qxe5 Rae8 Qxg7+ Rxg7 Be3 Rg6 a4 Bg4 Bg2 Bf5 axb5 axb5 Ra7 Kg7 d5 cxd5 Bd4+ Kg8 Bxd5 Be6 
29/12   0.00  Bf3 Rg8 Qd1 Bh3 Re1 f5 c4 Qg5 Rg1 Qh4 Re1
29/51  -1.07  Qe2 Rg8 Re8 Bg4 Rxg8+ Rxg8 Qxg4 Rxg4 Bxg4 Qh4 Bf3 Qxf2 Bxc6 Qe1+ Kg2 Qe2+ Kh1 b4 Bf3 Qd3 Kg2 bxc3 bxc3 Qxc3 Rb1 a5 Kf1 Bb4 a3 Bxa3 Bxa3 

The error is most likely within the series of 5 moves from move 21. to 26. If you send this pgn to Bryan-Stockfish, he may do backward forward analysis and microscope the blunder in more detail.

SugaR.AI.ICCF.1 thinks Bf3 is not good and prefere Qe1!

3 best moves :

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FEN: r1b2r1k/5p1p/p1pb3q/1p6/3PRp2/2P5/PP1N1P1P/R1BB1Q1K w - - 4 21

SugaR.AI.ICCF.1.00.popcnt:

 33/63	27:20	6 960 592 068	4 242 038	-0,88	21.Bf3 Rg8 22.Bg2 Bf5 23.Re1 Qh4 24.b3 Rg7 25.d5 f6 26.Ba3 Bxa3 27.Qe2 Bc5 28.Nf3 Qg4 29.Rg1 cxd5 30.Nd4 Bxd4 31.Qxg4 Bxg4 32.cxd4 f3 33.Bf1 Bf5 34.h3 Be4 35.Rxg7 Kxg7 36.a4 bxa4 37.bxa4 a5 38.Kh2 Kg6 39.Kg3
 34/106	27:20	6 960 592 068	4 242 038	-0,22	21.Qe2 Rg8 22.Re8 Bg4 23.Rxg8+ Rxg8 24.Qxg4 Rxg4 25.Bxg4 Qh4 26.Bf3 Qxf2 27.Bxc6 h5 28.Nf3 Qf1+ 29.Ng1 h4 30.Bf3 h3 31.a4 bxa4 32.Rxa4 Qxc1 33.Rxa6 Be7 34.Rh6+ Kg8 35.Rxh3 Qxb2 36.Bg2 Ba3 37.Rf3 Qd2 38.Nh3 Bb2 39.Rf1 Bxc3 40.Rxf4 Qc1+ 41.Rf1 Qh6 42.Rf2 Bxd4 43.Rf3 Be5 44.Rf2
 34/62	27:20	6 960 592 068	4 242 038	+0,07	21.Qe1 Bf5 22.Re5 Bh3 23.Nf1 Qg6 24.Bf3 Bxe5 25.Qxe5+ f6 26.Qe4 Bxf1 27.Qxg6 hxg6 28.Bxf4 Bc4 29.Bxc6 Rad8 30.Be3 Bd5+ 31.Bxd5 Rxd5 32.a4 Kg7 33.Kg2 Rf5 34.axb5 axb5 35.Ra7+ Rf7 36.Bh6+ Kg8 37.Ra8+ Kh7 38.Bf8 Rg5+ 39.Kf3 Rf5+

Yes, I saw that 21.Bf3 was a possible inaccuracy/ mistake that start turning white into trouble. As backward analysis is about x10 more powerful than forward analysis, I started to suspect that within 10-15 seconds in my phone.

[Ajedrecista]

Hello:

[...]

I did not find games with 17.- ..., Nf4 in this exact position, but ..., Nf4; gxf4, gxf4 looks like a thematic sacrifice just like RxN (..., Rxc3) in the Sicilian Dragon. [...]

The Total Marshall by Harding, Vitomskis and Bennedik states some attacking ideas for black, which can be considered typical tactical themes:

Attacking Ideas for Black

a) The ...f5-f4 thrust. This usually occurs after White has been induced to play g2-g3 and generally White has to answer ...f7-f5 by f2-f4 in order to prevent ...f5-f4, although there are exceptions.

b) The ...g7-g5 thrust. This is typical of the Pawn Push lines and can occur elsewhere, usually (but not always) when the f-pawns are locked as in idea a) just mentioned. The thrust ...h5 can also occur, but more rarely.

c) Infiltration down the e-file. In many variations, Black threatens to infiltrate the white position down the e-file, either after a queen exchange or if the white queen has gone on an excursion to f3. Black has two rooks quickly in play whereas White's a1-rook is slow to help in the centre, so an exchange of rooks on e1 or e8 can lead to Black controlling the important e-file. White often must play Be3 to keep the file blocked.

d) Sacrifices on f4: many situations arise when Black can play ...Bd6-f4 (or sometimes ... Nd5-f4) even though there is a white pawn on g3. This can happen whether or not there is a white pawn on f4. If the pawn is still on f2, it usually means a pseudo-sacrifice (gxf4 would open the g-file for a fatal check by a black queen or rook) whereas if the white pawn is on f4, then the motif is often a pin on the e-file.

e) The rook lift ...Re8-e6-g6/h6. The move ...Re6 occurs in a lot of games but sometimes the idea is just to double rooks - sometimes pinning a white bishop on e3.

f) Exchange sacrifices on e3 or e4. These tend to be associated with the Pawn Push variation but, except in certain circumstances, they are usually incorrect.

g) The Minority Attack. This only occurs in a few cases but can be effective when Black has restricted White's development, has a strong position and he is looking for a way to make progress. Generally in the Marshall, Black has the initiative on the kingside and e-file while trying to hold fast on the queenside, with his three queenside pawns restraining White's four. However, the advance ...b5-b4 can sometimes expose weaknesses in the white queenside. Also the move ...c6-c5, challenging the white d-pawn, sometimes has merit.

h) The long white diagonal. Except in the variation 11...Bb7, the diagonal a8-h1 is usually partially closed, but there are some cases where Black can make use of this diagonal to bring pressure on g2 which is a sensitive square in White's castled position. The diagonal can also be important in cases where White's Bxd5 can be met by ...Bxd5 (rare, but bad
news for White if it happens) or by ...Qxd5 (in the Spassky Variation).

The ..., g5 push is mentioned in idea b) whereas Bf4 and Nf4 are mentioned in idea d). The Marshall Attack is far from busted despite being analysed to death.

Regards from Spain.

Ajedrecista.

[MikeGL]

.
Thanks a lot for the mentioned references on Marshall and also for posting the attacking ideas for black.
The games you mentioned was probably swallowed by the engine during training, hence it got the
attacking idea Nf4 unlike other engines which have difficulty finding it as early as 17th move.

Hello:

[...]

I did not find games with 17.- ..., Nf4 in this exact position, but ..., Nf4; gxf4, gxf4 looks like a thematic sacrifice just like RxN (..., Rxc3) in the Sicilian Dragon. [...]

The Total Marshall by Harding, Vitomskis and Bennedik states some attacking ideas for black, which can be considered typical tactical themes:

Attacking Ideas for Black

a) The ...f5-f4 thrust. This usually occurs after White has been induced to play g2-g3 and generally White has to answer ...f7-f5 by f2-f4 in order to prevent ...f5-f4, although there are exceptions.

b) The ...g7-g5 thrust. This is typical of the Pawn Push lines and can occur elsewhere, usually (but not always) when the f-pawns are locked as in idea a) just mentioned. The thrust ...h5 can also occur, but more rarely.

c) Infiltration down the e-file. In many variations, Black threatens to infiltrate the white position down the e-file, either after a queen exchange or if the white queen has gone on an excursion to f3. Black has two rooks quickly in play whereas White's a1-rook is slow to help in the centre, so an exchange of rooks on e1 or e8 can lead to Black controlling the important e-file. White often must play Be3 to keep the file blocked.

d) Sacrifices on f4: many situations arise when Black can play ...Bd6-f4 (or sometimes ... Nd5-f4) even though there is a white pawn on g3. This can happen whether or not there is a white pawn on f4. If the pawn is still on f2, it usually means a pseudo-sacrifice (gxf4 would open the g-file for a fatal check by a black queen or rook) whereas if the white pawn is on f4, then the motif is often a pin on the e-file.

e) The rook lift ...Re8-e6-g6/h6. The move ...Re6 occurs in a lot of games but sometimes the idea is just to double rooks - sometimes pinning a white bishop on e3.

f) Exchange sacrifices on e3 or e4. These tend to be associated with the Pawn Push variation but, except in certain circumstances, they are usually incorrect.

g) The Minority Attack. This only occurs in a few cases but can be effective when Black has restricted White's development, has a strong position and he is looking for a way to make progress. Generally in the Marshall, Black has the initiative on the kingside and e-file while trying to hold fast on the queenside, with his three queenside pawns restraining White's four. However, the advance ...b5-b4 can sometimes expose weaknesses in the white queenside. Also the move ...c6-c5, challenging the white d-pawn, sometimes has merit.

h) The long white diagonal. Except in the variation 11...Bb7, the diagonal a8-h1 is usually partially closed, but there are some cases where Black can make use of this diagonal to bring pressure on g2 which is a sensitive square in White's castled position. The diagonal can also be important in cases where White's Bxd5 can be met by ...Bxd5 (rare, but bad
news for White if it happens) or by ...Qxd5 (in the Spassky Variation).

The ..., g5 push is mentioned in idea b) whereas Bf4 and Nf4 are mentioned in idea d). The Marshall Attack is far from busted despite being analysed to death.

Regards from Spain.

Ajedrecista.