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!

Kasparov plays the Mason Gambit

Happy New Year everyone!

Just stumbled upon a game from last August where Garry Kasparov, like Magnus Carlsen before him, wheeled out the Mason Gambit in blitz (1.e4 e5 2.f4 exf4 3.Nc3!?).
http://www.chessgames.com/perl/chessgame?gid=1883800

Unlike Carlsen's opponent, Karjakin did venture the critical response 3...Qh4+ but then after 4.Ke2 he went for the rather passive 4...Qd8.  As it was a blitz game he probably wanted to "play it safe" and the idea isn't completely without merit, for 4...d6 5.Nf3 Qd8 is one of Black's better responses, as discussed by John Emms in his 2000 book Play the Open Games as Black, giving a Fischer Defence where White has two extra tempi but one of them is the undesirable Ke1-e2.  As "brabo" discussed at the Chesspublishing.com forum some time ago, the most critical response of all is probably 4...Ne7 covering d5.

However, after the immediate 4...Qd8, Kasparov's continuation 5.d4 Nf6 (5...g5? 6.h4 doesn't work for Black) 6.Bxf4 regained the sacrificed pawn and led to a rather interesting middlegame where White relied on a strong centre to compensate for the exposed position of the white king.

It would seem that Kasparov lost his way into the early middlegame and was lucky to get a draw, but fair play to him for continuing in the spirit of the opening and going all-out, which is usually the best way to swindle a win or draw in a blitz game. 

43...Qc6+ would have won for Black, with the idea 44.Kg1 hxg6.  Instead 43...Qd2+? was played (it was a blitz game after all!) and Kasparov managed to get a draw.

Earlier on, the computer offers 7.e5 as a reasonable alternative to the 7.Bg5 played in the game, and also suggests 7.Nd5, although I would find it difficult to psychologically justify allowing the opening of the e-file towards the white king with ...Nxd5, exd5.