Trying out Stockfish 8

Having used a combination of old versions of Fritz and Rybka to error-check my chess analysis for years, I decided to give Stockfish 8 a go.  Ironically, this was prompted by Stockfish's much-publicised losses against Google's AlphaZero.  Yes, even bad publicity can be good.

I'm already finding that Stockfish sometimes disagrees with what Fritz and Rybka had to say on particular opening lines, and more often than not it tends to be right when I examine its suggestions closely.  For instance, I've previously examined the 13.Nxh7 sacrifice in Thiele-van Perlo, corr. 1987 in the Göring Gambit in the following position:

My previous examinations of the position suggested that 13.Nxh7 was dubious, and that 13.Ne6 was better, but a further examination with Stockfish suggests that 13.Ne6 is dubious because of 13...Bxe6 14.fxe6 and now the computer inconveniently points out 14...Ng8!, after which I can't see how White makes further progress.  Meanwhile, 13.Nxh7 appears to be sound, and may well be the best move in the position.  Thiele rather erred after 13...Kxh7 14.Bh5 g5 15.fxg6+, when after 15...Kg7 the g6-pawn blocks White's avenues of attack.  After instead 15.h4, it appears that White has at least enough for the piece in all lines.

I decided to feed Stockfish 8 a position that David Norwood used to show computers back in the 1990s, and which is sometimes thus known as the Norwood Position:

 Highlighting how far computers have advanced in the past 20 years, Stockfish 8 doesn't even look at the rook on a5, recommending that White shuffle the king, although it does erroneously assess the position at -17 pawns in Black's favour (the correct assessment is that it's a draw!).  If you enter 1.bxa5, it immediately gives mate for Black in circa 18 moves.

More challenging for the computer is if you replace the b-pawn with a bishop:

No, this wasn't originally my idea.  I can't recall where I first read it, but it is discussed in the Computer Chess News Sheet June-July 1994, so this might well be where the revised position originates from.  I recall feeding it to Fritz and Rybka some time ago and both computers insisted on grabbing the rook, but it might have changed with the latest commercial versions.

Stockfish 8 recommends 1.Bxa5 for a couple of minutes, assessing it as -5.2 pawns in Black's favour, and gives 1.Bb4 (the correct move) as -9.5 pawns in Black's favour, but then it picks up on 1.Bxa5 b4!, and within another couple of minutes it rejects 1.Bxa5 and gives 1.Bb4 followed by shuffling the king as best.  So even the revised version no longer stumps today's strongest computers.

There are of course still blockade positions that are even beyond Stockfish 8, but as computer AI continues to improve, they have to be more and more inventive.  I'm left wondering how AlphaZero, with its Monte Carlo method of calculation, would fare.  We might never know!

Another outing in the Göring Gambit, Scandinavian Gambits coverage completed

The Göring Gambit revisited

After many years of trying, I finally got a game in my favourite line of the Göring Gambit, which reaches this position after move 10:

Black's main options are 10...h6, 10...Ng6, 10...cxb5 and 10...Neg4, all of which lead to fascinating complications, though they have been heavily analysed.  My opponent went for 10...Neg4:

As is usual for club-level internet games, there were numerous mistakes, but it was certainly the sort of bloodthirsty and tactical game that I associate with the line.  Black's best response at move 12 is generally considered to be 12...b4, preventing White from taking on b5, after which White often ends up regaining the gambit pawn on h7 instead, whereupon the knight on h7 can turn out to be misplaced.  However, I don't see much wrong with 12...h6, which appears to lead to interesting and equal play.

I had previously intended to meet 10...Neg4 with 11.Be2, whereupon after 11...h6 12.Nf3 d5 13.h3, White hits out at the knight on g4, but Black has a few options that involve a tricky piece sacrifice, starting with 13...dxe4.

As well as adding coverage of "new" lines, I also intend, when I get time, to update the coverage of lines that I have previously covered at my Gambiteers' Guild site, with the aim of making the coverage more readable, with more explanations of the key ideas for both sides, cleaning up move-order issues, and doing a bit of trimming where I went into too much detail on some minor sub-sub-variation, and also getting some more practise with the ChessBase publishing format.   I have updated the Göring Gambit coverage at http://tws27.weebly.com/goring-gambit.html, http://tws27.weebly.com/goring-gambit-declined.html, http://tws27.weebly.com/goring-gambit-accepted-nxc3.html and http://tws27.weebly.com/goring-gambit-accepted-bc4.html but my opinions on most of the lines have not changed significantly since I last looked at them extensively.  

 Scandinavian Gambits revisited

I had posted earlier that I needed to put up coverage of White's important third-move deviations after 1.e4 d5 2.exd5 Nf6.  Otherwise, players itching to play 3.c4 e6 or 3.d4 Bg4 may be very disappointed if White wheels out 3.Be2 and then what?

I think the "Scandinavian gambits" and the Göring are quite closely related, as both involve challenging the opponent's e-pawn with the d-pawn and then offering it as a gambit, and Carl Theodor Göring, according to Stefan Bücker, also introduced the line 3.d4 Bg4 into master play.  The key difference, though, is that as Black has a tempo less, the approaches with an early ...c7-c6 tend to be unsound unless White plays c2-c4 first.

http://tws27.weebly.com/scandinavian-gambits.html
http://tws27.weebly.com/icelandic-gambit.html
http://tws27.weebly.com/portuguese-gambit.html
http://tws27.weebly.com/3rd-move-alternatives-for-white.html

The last of those four links contains the analysis of 3.Nc3, 3.Nf3, 3.Be2 and 3.Bb5+.  Three of the four illustrative games feature the Australian grandmaster David Smerdon on the black side, who is the leading exponent of these lines from Black's point of view nowadays.  His games have suggested that the line 3.Nf3 Bg4 is probably as playable as 3.d4 Bg4.

My verdict, in short:

The Icelandic or Palme Gambit, 3.c4 e6, is reasonably sound, but White might be able to get a small theoretical advantage with best play.  The critical line is 4.dxe6 Bxe6 5.Nf3.  Black's objectively best tries are then 5...Qe7 6.Qe2 Nc6 7.d4 Bf5, and 5...c5, which lead to an early queen trade, but Black's piece activity comes close to providing full compensation.  The lines with 5...Nc6, and 5...Qe7 6.Qe2 Nc6 7.d4 0-0-0, are more double-edged, but concede a larger advantage to White.

The Portuguese or Jadoul Gambit, 3.d4 Bg4 is theoretically dubious, but if it can work at grandmaster level, it should be sound enough for use at club level.  The main line, 4.f3 Bf5 5.Bb5+ Nbd7 6.c4, gives Black just a small theoretical disadvantage and good piece play after 6...e6 7.dxe6 fxe6.  5.g4 requires rather more courage to play from the white side, but is more theoretically critical.

If Black is happy to risk 3.d4 Bg4 then I think there is a compelling argument for meeting 3.Nf3 with 3...Bg4 as well, which is similarly dubious, but similarly offers good practical chances.

3.Be2 wipes out Black's gambit ideas but Black can get a combative game with 3...Qxd5.

3.Bb5+ can be met by either 3...Nbd7 or 3...Bd7.  Dave Smerdon's preference 3...Nbd7 is more likely to lead to double-edged play, while I don't think much of Black's winning chances in the line 3...Bd7 4.Be2 Nxd5 5.d4- though I am left wondering if Black can get away with playing 4...Bf5 before recapturing on d5.