Wednesday, 18 December 2019

Fun with a chess variant

As I prepare for another revamp of my main chess site, here's a bit of light entertainment.

At Exeter Chess Club I was recently playing in a chess variants tournament.  One of my favourites is the variant where if the king reaches one of the central squares (e4, d4, e5, d5) it is an automatic win for the player whose king reaches that square.  Otherwise normal rules of chess apply.  I was playing Black and reached the following position with White to move:

I had given up a queen for a rook in order to get my king out to d6.  In normal chess this position would be a straightforward win for White, but in this chess variant White has to be extremely careful as Black is only one move away from bringing the black king to the central squares and winning.

In the game White played 1.Qxe4 and resigned immediately after 1...Re8!.  In a normal game 2.Qxe8 would win, but in this chess variant, 2.Qxe8 would be met by 2...Kd5 0-1.  And if 2.Qxf5, Black wins normally with 2...Re1#, exploiting the weakness of the back rank.

A question is whether White can save this position despite being a queen for a rook ahead - this is the sort of chess variant that wouldn't work with computer analysis.  An obvious try is 1.Qb5, covering the central squares for the time being, but after 1...Nd4 2,Qg5 f5 or 2.Qa5 b5, White is struggling to keep the central squares covered and stop the black king from advancing.  1.Qa5 is probably best, but White has to watch out for ...Rc8-c5 and ...Re8-e5 ideas.

The opening saw me on the black side of a Four Knights Game (via an unusual move order, 1.Nc3 Nc6 2.Nf3 e5 3.e4 Nf6 I think).  My opponent then played 4.Bc4, allowing 4...Nxe4.  He remarked afterwards that in this chess variant the Halloween Gambit (4.Nxe5, the subject of my Halloween update to my website) would have been strong as in various variations it is difficult for Black to stop White from safely moving the king forward towards the centre.

I imagine that the Mason Gambit (1.e4 e5 2.f4 exf4 3.Nc3!?) and the allied Steinitz Gambit (1.e4 e5 2.Nc3 Nc6 3.f4 exf4 4.d4!?), inviting ...Qh4+, forcing Ke2, would also be good in this particular variant.

Thursday, 7 March 2019

A "very nearly brilliancy" in the Morra

I had a "very nearly brilliancy" in the Morra a couple of days ago, where I played what was probably my best ever attack up to move 21, sacrificing a piece and then an exchange in order to get a winning attack, but then threw it all away at move 22.  I had actually planned 22.Bh6 in advance, but talked myself out of playing it, thinking that 22.Be7 was "safer" because the bishop was defended by the queen...

The game began

1. e4 c5 2. d4 cxd4 3. Nf3 Nc6 4. c3 dxc3 5. Nxc3 g6 6. Bc4 d6 7. Qb3

Hitting f7, and encouraging ...e6, whereupon Black's Dragon formation "loses its shape", as Marc Esserman puts it in his book.

7...e6 8. O-O Nf6 9. Rd1 Qe7 $6 10. Bg5 

10. Bf4 is even stronger, with the idea of encouraging Black to weaken d5 further with 10...e5 11. Bg5.

10... a6?

10... Bg7 was best, and then if 11. Nd5?! (11. Bf4) (11. Nb5) 11... exd5 12. exd5 O-O
13. dxc6 bxc6.

11. Nd5

11. Bd5! was even stronger, but sacrificing the knight is the second best move in the position.

11... exd5 12. exd5 Ne5

12... Bg7 13. dxc6 O-O is objectively best, but then White has attacking
chances and the better pawn structure in a position with level material, and
the black pawn on d6 will probably drop off.

13. Nxe5 Qxe5

13... dxe5 14. d6 gives White a winning attack.

14. Re1

14. f4! would have been even stronger, preventing Black's ...Ne4 idea, but a couple of lines have to be calculated accurately.  The move played in the game is also winning for White, though.

14... Ne4

15. Rxe4! Qxe4 16. Qc3! Qe5

I saw 16... Bg7 17. Qxg7 Rf8 18. Bh6 Qe7 19. Qc3 renewing the threat of Re1.

16...f6 17. Re1 Qxe1+ 18. Qxe1+ Kf7 is Black's best chance, whereupon White has to
find 19.Bxf6! to get a winning position.

17. Re1 Bg7
17... Qxe1+ 18.Qxe1+ Kd7 gives White a choice of winning continuations. For example, 19. Bf6 Rg8 20. Qe3 b5 (20... Kc7 21. Qe8) 21. Qb6! forces mate.)

18. f4!

18. Rxe5+? Bxe5 followed by ...0-0 is probably alright for Black.

18...Qxe1+ 19. Qxe1+ Kf8 20. Qe7+ Kg8 21. Qe8+ Bf8 

Unfortunately this is the point where I bottled it.  22.Bh6, which was my original intention, forces mate in four moves, but I somehow convinced myself that Black could wriggle out, and consequently played a "safer" move that allowed Black to wriggle out...

22. Be7?? Kg7! 23. Bxf8+?! 

As is often the case after the psychological blow of missing a quick win, I rather went to
pieces. 23. Bh4 would still have left White with a strong, possibly winning,

23... Rxf8 24. Qe4?! Bf5 25. Qd4+ Kg8 26. Qb6 Rac8 27. Bb3?! Rfe8 and Black went on to win.

Unfortunately I have been forced to link to the game rather than embed a replayable game into the blog post, because at least at my end I seem to have triggered some sort of block that is stopping me from viewing replayable chess games in my own blog (but not other people's blogs).

An agonising loss, but I do seem to have improved my attacking play a bit recently - a common past failing of mine has been to be too eager to "cash in" and missing the quiet moves (like 16.Qc3 and 18.f4 in the above game).  I think had I reached the position at move 15 this time last year I would probably have been preoccupied with trying to regain the piece with f2-f3 and it is unlikely that I would have had the guts to play 15.Rxe4.

Having seen a number of AlphaZero-Stockfish matches recently, I think I may well have been inspired by AlphaZero's willingness to sacrifice pawns and even pieces and then quietly improve its position.

Sunday, 3 June 2018

RIP Valeri Yandemirov

I've just found out via that Valeri Yandemirov passed away last year at the age of 55:

Not a household name, but he was a grandmaster with a peak rating of 2545 in 1998, and he was rated in the 2500s for most of the "noughties" as well.

The main reason why the name sticks out for me is that he was a big practitioner of two daring and sacrificial lines in the Ruy Lopez Modern Steinitz Defence: the Siesta Variation (1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 d6 5.c3 f5) and the line 5.0-0 Bg4 6.h3 h5, which some have started naming after him (notably Timothy Taylor in his book Slay the Spanish).  The idea most commonly associated with Yandemirov was, after 7.d4 b5 8.Bb3 Nxd4 9.hxg4, to play 9...Nxb3 (instead of 9...hxg4 10.Ng5 Nh6, which has been shown to be insufficient for Black) 10.axb3 hxg4 11.Ng5 Qd7.

 Black is currently a piece down but can generally regain the piece with ...f6 and ...fxg5 since the knight on g5 has no retreat square.  The main idea is however to play ...Qf7 and ...Qh5 and try to mate White down the h-file.  On the other hand this line is still theoretically dodgy because in the meantime White can smash Black on the queenside.  The line was dealt quite a heavy blow in the game Gashimov-Grischuk, Baku 2008:

Nowadays, while 4...d6 has seen some popularity at the highest levels, GMs such as Shakhriyar Mamedyarov and Nigel Short have tended to prefer 5...Bd7 over 5...Bg4, but the 5...Bg4 line has still seen a few recent GM outings, particularly in the hands of Laurent Fressinet:

Aseev-Yandemirov, Krasnoyarsk 2003 was arguably the greatest advert for his pet line:

I have tried these lines out myself from time to time since 2009 and currently have an online game that has reached the position after 6.h3 h5.  I tend to think that if it can work at GM level it must be good enough for mere mortals, even though it may be of marginal theoretical soundness.

Monday, 16 April 2018

An intriguing transposition from the Albin Counter-Gambit into the Göring Gambit Declined

I've probably mentioned the transposition from the Chigorin Defence before (it was also mentioned about a year and a half ago over at 200 Open Games).  Recently I managed to get it in one of my own online games, fittingly, in a match between "The Gambit Players" and "Philippine C", and it actually started out as an Albin Counter-Gambit: 1.d4 d5 2.c4 e5, and White replied with the tame 3.e3.  After 3...Nc6 4.cxd5 Qxd5 we were into a Chigorin, and after 5.Nc3 Bb4 6.Nf3 exd4 7.exd4 we were into a Göring/Danish Gambit Declined.

Capablanca's line with 7...Bg4 8.Be2 (8.Be3!? - Mark Nieuweboer) 8...Bxf3 9.Bxf3 Qc4 gets pretty sterile if White knows what he/she is doing, so I was tempted to duck out with the sensible 8...Nf6, but as I was playing a slightly higher-rated player with Black I thought I would test my opponent out in the Capablanca Variation.  It worked, for after 7...Bg4 8.Be2 Bxf3 9.Bxf3 Qc4 10.Bd2?! 0-0-0 11.Qe2?! Qxe2+ 12.Bxe2 Nxd4 I was already a pawn up and managed to win with the extra pawn after a long struggle.

In the meantime I finally had an outing in the line that I had corresponded with Gary Lane about over at Opening Lanes (  1.e4 e5 2.d4 exd4 3.Nf3 Nc6 4.c3 d5 5.Bd3!? dxe4 6.Bxe4 Nf6 7.Bxc6+ bxc6 8.0-0 (which both of us suggested independently of each other).  I got some pressure in the IQP middlegame that ensued but did not make the most of it and ended up with a draw, but my opponent came close to losing on time.

Also I'm currently working on what will probably end up as a book-sized pdf article on the "open gambits" with an early d2-d4 (including the Italian and Max Lange gambits as well as the Danish, Göring, Scotch and Urusov) so that all the various transpositions will be handled in the one pdf file, and there will be links to replayable annotated examples in the text.  It's an ambitious project so it may well take me several months, but it would be satisfying to pull it off.

Wednesday, 24 January 2018

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!