Friday, November 24, 2017

Jerome Gambit Declined: Long But Not Winding Road

The following is one of two recent Jerome Gambit Declined games played between Petasluk (408 games in The Database, scoring 65%) and ROYBY. The other was a win on time by ROYBY, after the game had reached a drawn Bishops-of-opposite-colors endgame.

The JGD can lead to quiter play than the main lines, but White is in less of a hurry, as he has the advantage in material. 

Petasluk - ROYBY
5 0 blitz, FICS, 2017

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ 


The Jerome Gambit Declined. Even though White has scored only 55% against it in the games in The Database, I cannot recommend it for Black. The defender gives up the opportunity of being two pieces up (with an insecure King) to be one pawn down (with an insecure King).


Of course, White could also have withdrawn the Bishop.

5...Kxg8 6.c3 h6 7.d4 exd4 8.cxd4 Bb6 

A pleasant, if somewhat unsual position for the Jerome Gambit player - better pawn center, safer King, and ahead in material.

9.O-O Qe7 10.Re1 d6 11.Qb3+ Qf7 12.d5 Na5 

Removing the Knight from danger and attacking the enemy Queen - all in one move. But, seriously, folks, the stronger idea was 12...Ne5.

13.Qd3 Bd7 

Intentionally or not, Black abandons his Knight. He could have tried 13...c5, after which 14.dxc6 Nxc6 15.Qxd6 would net a pawn for White.

Interestingly enough, Stockfish 8 would prefer to ignore the offside Knight, and answer 13...c5 with 14.Nbd2!? Bc7 15.b3 Qg6 16.Bb2 Bd8 17.Qc3 b5 18.e5 b4 19.Qc1 Bh3 20.g3 Be7 21.exd6 Bxd6 22.Ne4 Qf7 23.Qe3 Nb7 24.Rad1 Rc8 25.Nxd6 Nxd6 when White has better development and Black's semi-castled King blocks one of his Rooks. Quite an improvement over the days when computers were pawn grabbers! 

14.b4 a6 15.bxa5 Bxa5 16.Bd2 Bb5 17.Qe3 Bb6 18.Qc3 Kh7 19.a4 Bd7 20.Be3 c5 

Black's c-pawn comes to the rescue of his Bishop, but probably simpler - if annoying, as it is not always the first choice to exchange pieces when you are behind in material - was 20...Bxe3.

21.dxc6 Rac8 22.Bxb6 Rxc6 23.Qb2 Bg4 24.Nbd2 Rf8 

Black has all of his pieces developed, but there are not enough of them.

25.Rac1 Bd7 26.Rxc6 Bxc6 27.Qc2 Kh8 28.Qd3 Qe7 29.Nd4 Bxa4 30.Nf5 

A slip that neither player notices: the Knight is not protected. White's e-pawn is effectively pinned, as 30...Rxf5 31.exf5? Qxe1 would be checkmate. If White didn't panic, he could still be better after 30...Rxf5 31.Nc4.

30...Qe5 31.Nxd6 

Clearly good enough to win. The ever-watchful Stockfish 8 suggests the very aggressive alternative, 31.Bd4!?, which both attacks the Black Queen and, through it, Black's Kingside. One possible outcome is 31...Bb5 32.Qa3 and White has too many threats.

31...Bc6 32.Nf3 Rf4 

A final slip, perhaps due to the clock. 

33.Nxe5 Black resigned

Wednesday, November 22, 2017

Jerome Gambit: Give Me A Break

I have maintained The Database of Jerome Gambit games to help me get a sense of how certain lines or moves succeed or fail - from a practical (i.e. over-the-board play) point of view.

I have used chess analysis engines (currently Stockfish 8) to get a sense of how certain lines or moves are "objectively" strong or weak.

It is a joy when both the practical and the analytical agree. It can be confusing when they don't. Take the following game. It left me a bit confused...

Petasluk - givemeabreak
5 0 blitz, FICS, 2017

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ 

4...Kxf7 5.Nxe5+ Nxe5 6.Qh5+ Kf6 

Including this game, Petasluk has reached this position 7 times according to The Database (which, I admit, need some updating). Before this game he was 2-1 with the followup 7.Qf5+ and 2-1 with 7.f4. This compares with statistics from the whole Database - White scores 80% (35 games) with 7.Qf5+ and 80% (10 games) with 7.f4.

So, from a practical point of view, 7.Qf5+ and 7.f4 are both good move choices, according to Petasluk's experience; and both are excellent choices from the experience of those represented by The Database.


So, no surprise here.

Yet the computer analysts, starting with Stockfish 8, leap directly for the straightforward 7.Qf5+ Ke7 8.Qxe5+ Kf8 9.Qxc5+ picking up the two sacrificed pieces.

Why the discrepancy?


Well, here is one reason: the defender in this game is human, and humans make mistakes. The alternative 7...Nc6, withdrawing the attacked piece, allows White to only recover one of his sacrificed pieces:  8.Qf5+ Ke7 9.Qxc5+ Kf7, with pressure on the enemy King, but not full compensation for his offerings.

8.Qxe5+ Kf7 9.Qxh8 Black resigned 

Well, it looks like "Practical Experience 1, Computer Analysis 0".

But that is not the whole story. A number of Petasluk's games continued from the above "final" position:

9...Nf6 (9...d6 10.Qxh7+ Kf8 11.d3 Qf6 12.Qxc7 Be3 13.Nc3 Qxf4 14.Rf1 Qxf1+ 15.Kxf1 Bxc1 16.Rxc1 Black resigned, Petasluk - douthy, FICS, 2015; or 9...Qe7 10.Qxh7+ Kf6 11.Qxg8 Qxe4+ 12. Kd1 d5 13.Qh8+ Kf5 14.Qh3+ Kxf4 15.Rf1+ Kg5 16.Qg3+ Bg4+ 17. Rf3 Re8 18.c3 d4 19.h3 Qe2+ 20.Kc2 d3+ 21.Rxd3 Qd1 checkmate, Petasluk - kosten, FICS, 2013) 10.Qxd8 Black resigned Petasluk - skaks, FICS, 2015 and Petasluk - kaliz, blitz, FICS, 2014 Be7 11. Qh8 11... b6 12. e5 Bb7 13.Qxa8 Bxa8 14. exf6 Bxf6 15. O-O Be4 16. d3 Bc6 17. Nc3 Black resigned, Petasluk - TaccyChan, FICS, 2007.

That's 4 wins and 1 draw. More support for practical considerations.

But I expect the "Wait 'til next time!" bunch will want to look closer at 7.Qf5+.

(Where did the "extra" games come from? Petasluk - TaccyChan, FICS, 20017; Petasluk - Kosten, 2013 and Petasluk - douthy, FICS, 2015; all transposed from 6...Ke6.)

Monday, November 20, 2017

Blackburne Shilling Jerome Gambit: Risk vs Experience

The following game is a riot of a 3-minute battle, as White takes risks and even more risks, while Black relies on his experience in the line - up to a point. This time, fortune favors the bold - but only half-way.

By the way, shugart has 140 games in The Database, scoring 60%. Nice.

shugart - boggus
3 0 blitz, FICS, 2017

1.e4 e5 2.Nf3 Nc6 3.Bc4 Nd4 

The Blackburne Shilling Gambit.


The Blackburne Shilling Jerome Gambit. White has alternatives, but this move is a lot of fun.

4...Kxf7 5.Nxe5+ Ke6 6.Qg4+ 

Tempting, as we have seen before (for example "Jerome Gambit: Missed by That Much") - especially in blitz games - but best, from experience and by analysis, is 6.c3. 

6...Kxe5 7.f4+ 

In for a penny, in for a pound.

Boggus has grabbed the Knight before, for example: 7.c3 Nc2+ 8.Kd1 Nxa1 9.d4+ Kd6 10.Na3 h5 11.Nb5+ Kc6 12.d5+ Kxb5 13.Qe2+ Kb6 14.Be3+ c5 15.a4 Kc7 16.Qb5 d6 17.Bf4 Kb8 18.Qxc5 Qb6 19.Qc4 Qxb2 20.Ke1 Nc2+ 21.Kf1 Qb1+ 22.Ke2 Qxh1 23.Qb3 Qe1+ 24.Kf3 Bg4+ 25.Kg3 Qxe4 26.f3 Bxf3 27.gxf3 h4+ 28.Kh3 Qxf3+ 29.Bg3 hxg3 checkmate, Tigrann - boggus, FICS, 2008.

White could have tried 7.Qh5+ (e.g. 7...Kf6 8.d3 Ne7 9.Bg5+ Ke6 10.Bxe7 Nxc2+ 11.Kd1 Kxe7 12.Kxc2 d6) but he will eventually be done in by his generosity.

Better to remember the 6.c3 line for next time.


The two likely reasons White likely sacrificed the Knight are these alternatives: 

7...Kxe4 8.Nc3 checkmate; and

7...Kf6 8.Qh4+ Kf7 9.Qxd8. 

Don't laugh. Such threats are the meat and potatoes of blitz chess.


White might as well keep attacking, as the more prudent 8.Na3 c6 9.c3 Nb5 10.Nxb5+ cxb5 doesn't get him out of his material deficit.


Black played the stronger 8...Kc6 in two earlier games, but they were long ago: 9.Qd1 (9. c3 Nc2+ 10.Kd1 Nxa1 11.Qf3+ d5 12.b4 a6 13.a4 Be6 14.c4 Bxb4 15.Bb2 Qd7 16.Bxa1 Bg4 17.cxd5+ Qxd5 18.Qxg4 Ne7 19.Qxg7 Rhd8 20.Qf6+ Kc5 21.Qxe7+ Kc4 22.Qxc7+ Qc5 23.Qxc5+ Bxc5 24.Ke2 Bd4 25.Bxd4 Rxd4 26.d3+ Rxd3 27.Rc1+ Kd4 28.Rc7 Rd8 29.g4 Ke4 30.Rc4+ R3d4 31.Rxd4+ Rxd4 32.Nd2+ Kxf4 33.e6 Rd8 34.g5 Kxg5 35.Ne4+ Kf5 36.e7 Re8 37.Nd6+ Ke6 38.Nxe8 Kxe7 39.Ng7 Kf7 40.Nh5 Ke6 41.Ng3 b5 42.Nf1 b4 43.Kd2 a5 44.Kc2 Kd5 45.Kb3 Kd4 46.Nd2 Kd3 White forfeited on time, GROFVLAD - boggus, FICS, 20079...d5 10.c3 Nf5 11.O-O b6 12.d4 Ba6 13.Rf2 Qh4 14.Nd2 Nge7 15.Nf3 Qh5 16.e6 Kb7 17.Ne5 Nc6 18.b4 Qxd1+ White resigned, GOH - boggus, FICS, 2009.

Still, if he keeps his wits about him, all will be well for Black. 

9.f5 Nxc2+

Often in the BSJG the Rook on a1 is poisoned, but not in this case. You have to wonder though - was Black a little bit suspicious as to why White let it go? Did it nag at him: Maybe White is up to something...?

10.Kd1 Nxa1 

True, 10...d5 is probably best, but Black is still better after the game move.


Hopeful. If you don't have hope, you can't play Jerome lines.


We know why Black played this.

It would be very impressive if it was because he remembered the following game: 11...d5 12.Bg5+ Nf6 13.exf6+ gxf6 14.Re1+ Kd6 15.Bf4+ Kc6 16.Re3 Bd6 17.Rc3+ Kd7 18.Bxd6 cxd6 19.Nd2 Qg8 20.Qh3 Qg5 21.Nf3 Qf4 22.Qh5 Qe4 23.Qf7+ Qe7 24.Rc7+ Kxc7 25.Qxe7+ Kb6 26.Qxd6+ Kb5 27.Qxd5+ Kb6 28.Qc5+ Ka6 29.b4 b6 30.b5+ Kb7 31.Qc6+ Kb8 32.d5 Bxf5 33.d6 Rc8 34.Qd5 Rc5 35.Qg8+ Kb7 36.Qxh7+ Kc8 37.Qg8+ Kb7 38.Qf7+ Kc8 39.Qe8+ Kb7 40.Qe7+ Kb8 41.Nd4 Bc2+ 42.Ke1 Bf5 43.Nc6+ Kc8 44.Qd8+ Kb7 45.Qc7 checkmate, GOH - boggus, FICS, 2004

Black wants the Black Bishop to stay away from g5, but White now grabs the half-point on the table.

12.Qh4+ Ke8 

The alternative, 12...g5, is met by 13.Bxg5+ hxg5 14.Qxg5+ Ke8 15.Qg6+ Ke7 16.Qg5+ etc.

13.Qh5+ Ke7 14.Qh4+ Ke8 15.Qh5+ Ke7 16.Qh4+ drawn by repetition