The Subtlest of Differences

by admin on February 5, 2016

One of these positions is a win for White. The other is a draw. Can you tell which is which?

Position 1:

subtlest 1Position after 51. … Kd4. White to move.

FEN: 8/1p3p2/8/p2p2p1/P2k2Pp/1P1B3P/6K1/8 w – - 0 52

Position 2:

subtlest 2Position after 51. … Kd4 (alternate reality). White to move.

FEN: 8/5p2/1p6/p2p2p1/P2k2Pp/1P1B3P/6K1/8 w – - 0 52

While you’re thinking about it, here’s the story. Last night I was playing another training game against Shredder (set at a rating of 2275). I played a really good game up through about move 38, won a pawn and had complete control over the position. But the thing about computers is that they never get discouraged. Where a human might have given up, it was constantly looking for a way to keep the battle going. It spotted a chance to sac a piece for three pawns, and we got to Position 1, where I suddenly realized it was going to be very hard to win. In fact, I wasn’t sure I could win at all.

I decided to take my time-out here and see if I could figure out what to do. My initial inclination was to play 52. Bb5, but I couldn’t see a clear win after 52. … Ke3! If White plays 53. Kf1 to block the d-pawn, then 53. … Kf3! switches the attack over to the h-pawn. If White just waits, Black will push his pawn to d3 and then play … Kd2 and … Kc2, with a draw at least.

Then I saw that I could play 52. Be2!, which I think is the only winning move. The point is that now 52. … Ke3 can be met by 53. Bf3 d4 54. Bxb7! The win of the b-pawn is just enough to tip the balance in White’s favor, for example 54. … d3 55. Bf3 Kd2 56.Kf2 Kc2 57. Ke3 d2 58. Be2 f6 59. Kd4 d1Q+ 60. Bxd1 Kxd1 61. b4! ab 62. a5 Kc2 (if 62. … f5 White just ignores the f-pawn and lets it take on g4 and h3 if it wants) 63. a6 b3 64. a7 b2 65. a8Q b1Q 66. Qe4+ (diagram)

subtlest 3Position after 66. Qe4+ (analysis). Black to move.

FEN:8/8/5p2/6p1/3KQ1Pp/7P/2k5/1q6 b – - 0 66

White wins by trading queens and marching his king over to the kingside. Black’s king is too late to defend any of his pawns.

I actually didn’t work this all out during my time-out; it’s Rybka analysis. But I had the feeling that the position was winning if I could take the b-pawn, and Rybka confirms that.

So we can see that the position of the b-pawn mattered a great deal! In Position 2, the Be2-f3 trick doesn’t work, and in fact Rybka confirms that the endgame is a draw. I was really lucky here, because the position of the b-pawn on b7 or b6 was completely irrelevant up to this point and Shredder could easily have played … b6 earlier in the game. If it had, I’d be showing this game to you as an example of a blown win; instead it was a lucky save of an almost-blown win.

But that’s not all! The endgame continued to be quite interesting, and in fact I did blow the win just one move later! In position 1, after I played 52. Be2! Shredder moved its king in the opposite direction: 52. … Kc3! During my time-out I had not sufficiently thought about the difference between the two moves … Ke3 and … Kc3, and I mistakenly thought that the same plan worked in both cases. I played 53. Bf3??, which only draws! 53. Kf3! was correct, and this time I’ll leave the details to you (or Rybka) to work out. Play continued 53. … d4 54. Bxb7 d3 55. Bf3 Kxb3 56. Kf2 and now it was Shredder’s turn to blunder.

subtlest 4Position after 56. … Kf2. Black to move.

FEN: 8/5p2/8/p5p1/P5Pp/1k1p1B1P/5K2/8 b – - 0 56

Black has two natural-looking moves, 56. … Kc2 and 56 … d2. One draws and one loses. Can you tell which is which?

(space inserted in case you want to think about it)

Shredder played 56. … Kc2??, which loses! This is when playing a computer opponent is less satisfying than playing a human opponent. If it were a human, we could talk about why it made this mistake. Normally I have a rule: control the squares in front of the passed pawn first, then push the pawn. So 56. … Kc2 would seem to be the right choice. But this position is an exception to the rule! I played 57. Be4!, which paralyzes the pawn and allows White to blockade successfully on d1… with the king.

After 56. … d2! White has to blockade with the bishop, and that makes all the difference! For example, 57. Bd1+ Kb2 58. Ke3 Kc1 59. Ke2 f6! and White is done in by the lack of mobility of his bishop. He has nothing better than repeating the position with 60. Bb3 Kb2 61. Bd1, etc. White would be winning if we took the pawns at a4 and a5 off the board.

Alternatively, if White tries for a pawn race with 56. … d2 57. Ke3 Kc2 58. Ke4 d1Q 59. Bxd1+ Kxd1 60. Kf5, both sides queen and White doesn’t have any neat trick at the end as he did in diagram 3.

Why didn’t Shredder play 56. … d2!? Well, here is where playing against a computer is less satisfying than playing against a human. If it were a human, we could talk about it being misled by the general rule. But being a computer, it doesn’t think in terms of rules. It just computes. Remember that I had its strength set at 2275. When its strength is set to less than the maximum, it must be programmed to make a mistake now and then. So it didn’t make a conceptual error, it just had some random number generator coming up snake-eyes. “Time to make a mistake!” Boo.

Even so, the game still continued to be interesting and poised on a knife edge between a win and a draw. I have one more “Subtle Differences” position to show you. We’ve already seen subtle differences between a pawn on b7 or b6, between a king moving to c3 or e3, between blockading with a bishop and a king, and between having the a-pawns on the board and not having them there.

After 56. … Kc2?? the game continued 57. Be4! Kc2 58. Ke1 Kd4 59. Bf5 Ke3 60. Bh7 d2+ 61. Kd1 (success!) Kf4 62. Kxd2 Kg3 63. Ke3 Kxh3. I swear, playing the computer is like battling the Hydra. I cut off one passed pawn (the d-pawn), now a new and dangerous passed pawn appears on the h-file.

Moving on: 64. Kf3 Kh2 65. Kf2 Kh3 66. Bf5 f6 67. Be6 Kh2 68. Bd5 f5. The computer seizes its last chance to muddy the waters. 69. gf g4 and let’s pause for a diagram.

subtlest 5Position after 69. … g4. White to move.

FEN: 8/8/8/p2B1P2/P5pp/8/5K1k/8 w – - 0 70

White to play and win. Oh, that’s too easy. Let me make a change.

subtlest 6Position after 69. … g4 (alternate universe). White to move.

FEN: 8/8/8/3B1P2/6pp/8/5K1k/8 w – - 0 70

Now White to play and win. Do you see the trick?

In the real game, I looked at 70. Bg2 and discovered, to my horror, that 70. … h3 71. Bxh3 gh 72. f6 Kh1 73. f7 h2 74. f8Q was stalemate! So I looked around for other possibilities and found 70. Ke2 g3 71. f6 h3 72. f7 g2 73. f8Q! g1Q and now not 74. Qf2+?? Qxf2+ 75. Kxf2, which would again be stalemate, but 74. Qf4+! Qg3 75. Qxg3+ Kxg3 76. Kd3 and I won in a few more moves.

However, this line only worked because I still had an a-pawn that I could queen. What if we were in an alternate universe where the a4 and a5 pawns weren’t there?

Well, in the alternate universe White is still winning, because after the line in blue above (70. Bg2 h3 71. Bxh3 gh 72. f6 Kh1 73. f7 h2) instead of queening the pawn like a sucker, White instead plays 74. Kg3! letting Black’s king out of captivity. Now 74. … Kg1 75. f8Q h1Q 76. Qf2 mate! Black could of course avoid the mate by promoting to a knight instead (75. … h1N+), but the knight is no match for a queen.

To be honest, I completely missed this idea when I was playing the game, so I’m lucky that the a-pawns were still there to give me an alternative winning method. The reason for my oversight is psychologically interesting. I have definitely seen this trick before (letting him queen and then checkmating him, with the newly promoted queen taking away the king’s only flight square). It comes up in a Q vs. RP endgame when the stronger side’s king is sufficiently close to the queening square. But I wasn’t prepared to see this theme emerge out of a bishop-and-pawn endgame.

I wish I could tie this post all up in a nice little bow for you, but what I think it shows is that in some types of endgames, every little detail matters. You can’t just go on general rules and principles. The evaluation of the position and the optimal plan can change if you just move one pawn from b7 to b6, or move your king left instead of right. Which is, of course, quite discouraging if you’re trying to learn how to play endgames!

Oh yes, and one other practical piece of advice, which came up in both diagrams 3 and 6: When analyzing a pawn race, do not stop your analysis when both pawns promote. There’s a tendency to assume that if they both promote, the race is a tie. But you should always make sure to look at least one move farther ahead, to see if there are any surprising checks (or checkmates!).

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The Van Damme Truck Trick

by admin on February 1, 2016

I’ve got a new tactical trick for you! Of course, there is nothing new under the sun in chess, but this is a sneaky trick involving two rooks that I don’t think has ever been given a name before. (I hope someone will correct me if I’m wrong.) I’m going to call it the Van Damme Truck Trick, until somebody comes up with a better name.

Let me set the stage. Last night I was playing against Shredder, with its strength set at 2275. I know, a few months ago I swore never to do that again, because I was so infuriated at its “Coach” feature, where it tells you, “I think your last move was not so good. Are you sure you want to do that?” Well, in this game the Coach actually taught me something. I still hate it, because it destroys any semblance of real chess, but anyway, here is the position. I’m playing Black.

van damme trick 1Position after 40. Bc6. Black to move.

FEN: 1r6/p5p1/2B1k2p/2P1p3/3bR1PP/P7/5r2/2RK4 b – - 0 40

As you can see, I have a wonderful position, and I played the move 40. … Rc8, which wins a pawn.

Shredder: “I think your last move was not so good. Are you sure you want to play it?”

Dana: What has that computer been smoking? Oh, I see! It thinks I should play 40. … Rd8, threatening checkmate.

Shredder: “I think your last move was not so good. Are you sure you want to play it?”

Dana: Okay, of course. On 40. … Rd8 it could just play 41. Ke1, and on 41. … R8f8 42. Bb5 what have I gained? Hmm… There must be something else in this position that I’m not seeing. It’s kind of a shame to take my rook off the b-file, where it’s already so well placed. Wait! I have an idea! I don’t even have to move the rook to c8! I can just take the pawn on c5 right away, with 40. … Bxc5!!

Shredder: “I think your last move was not so good. Are you sure you want to play it?”

Dana: Are you ****ing serious? 40. … Bxc5 is a brilliant move! That computer needs to be punished. Would turning it from a Mac into a PC be punishment enough?

Of course, there is a problem that after 40. … Bxc5 it doesn’t have to accept my sacrifice. It could just play 41. Ke1, and after 41. … Bb6 yes, I’ve won a pawn, but it’s only a pawn. Somehow there must be a way to get even more out of this idea.

And then the light dawned on me. Have you figured it out yet?

The absolute best move in the position is 40. … Bc3!!

van damme trick 3Position after 40. … Bc3!! White to move.

FEN: 1r6/p5p1/2B1k2p/2P1p3/4R1PP/P1b5/5r2/2RK4 w – - 0 41

The main point of this move, like 40. … Bxc5, is that it sets up the Van Damme Truck Trick. You remember the Volvo Truck commercial from 2013, when Jean-Claude Van Damme is standing on top of two trucks that are driving down a road, and they gradually move apart until Van Damme is doing a split between them at 60 miles an hour?

Well, here the White rooks are the trucks and the White king is Van Damme. After 41. Rxc3 (which Shredder played) Rb1+ 42. Rc1 Rf1+ 43. Re1 (which Shredder didn’t play) we arrive at the following amusing configuration.

van damme trick 4Position after 43. Re1 (analysis). Black to move.

FEN: 8/p5p1/2B1k2p/2P1p3/6PP/P7/8/1rRKRr2 b – - 0 43

Here we see the point of the Van Damme Truck Trick. It looks as if White has successfully defended against both of Black’s rook checks. But now his king is like Van Damme doing a split between the two trucks — and if they move just a little bit too far apart, well, you can figure out what happens. 43. … Rxe1+! 44. Kxe1 Rxc1+ and White loses an exchange and a pawn and the game.

As I said, Shredder elected not to go into the pure version of the Van Damme Truck Trick and returned the rook immediately with 43. Kd2. I actually took the wrong way — 43. … Rbxc1? (43. … Rfxc1 was better) but I eventually managed to win the game anyway.

You might wonder, why was 40. … Bc3 better than 40. … Bxc5? The reason is that it’s more forcing. Black threatens mate with 41. … Rd8+, and White is forced to take the bishop one way or another. (He could alternatively play 42. Re2 Rd8+ 43. Kc2 Rxe2+ 44. Kxc3.) However, I really think that 40. … Bxc5 should get full credit too, provided that Black sees that 41. Ke1 can be met by 41. … Bxa3!, winning a second pawn. It’s really a matter of taste: do you prefer to be two pawns up in an OCB endgame, or do you prefer to be an exchange up? I think that the reason Shredder gave me the dreaded Coach message is that it evaluated the position after 40. … Bc3 as +4 pawns for Black, while the position after 40. … Bxc5 was only +2 pawns. Therefore it considered 40. … Bxc5 a bad blunder.

Anyway, to me the main point of the position is to see the Van Damme Truck Trick. Whether you set it up with 40. … Bxc5 or 40. … Bc3 is secondary.

Question for my readers: Do you know any examples of the Van Damme Truck Trick in master play? It’s one of those things that I know I’ve seen, but I don’t know where. I did lose a game a few years ago to a similar trick, but it’s not quite the same.

van damme trick 2Position after 21. Rxh6. Black to move.

FEN: 3rkr2/pp2p3/2p1p2R/4P1p1/8/6P1/PPP2PP1/2K4R b – - 0 21

This position occurred in the 2003 U.S. Open in Los Angeles. I was playing Black against a class-A player named Patrick McCartney. I think that I would have pretty close to equal chances after 21. … Rd5, thanks to my active rooks, but instead I got careless and played 21. … Rxf2??, thinking it was a free pawn. Too late, after he played 22. Rh8+!, I realized that I lose a whole rook after either 22. … Rf8 23. Rxf8+ Kxf8 24. Rh8+ or 22. … Kd7 23. Rd1+, and so I resigned. This trap does have elements of the Van Damme Truck trick in the sense that Black’s king gets checked from two different directions. Each check by itself is harmless, but the combination of the two is fatal.

Finally, if anyone can think of a better name than the Van Damme Truck Trick, I’d be glad to take suggestions. I’m looking for a metaphor that conveys the idea of being pulled in two directions at once.

I briefly thought about the Levi’s Jeans Trick, because their logo shows (or used to show?) a pair of jeans being pulled in two directions by two horses, as a way of emphasizing their toughness (the fabric is held together by rivets). But I didn’t like that name as well because I didn’t think anyone would get it. Another possibility is the Magdeburg hemispheres, a physics experiment designed by Otto von Guericke in the 1600s to prove the existence of the vacuum. He placed two copper hemispheres together, pumped out the air between them, and then a team of 24 horses pulling in opposite directions was unable to pull them apart. As wonderful as this example is, if I called this the Magdeburg trick no one would have the slightest idea what I was talking about. So for the time being, it’s the Van Damme Truck Trick.

Update, 2 hours later: Paul b. suggested the Three Stooges Trick. The king is Larry, and the rooks are Curly and Moe. Smack Curly on the left and Larry will look that way, and then you can whack Moe on the right. I like it! 

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Checkmate Patterns, Moral Victories

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Yesterday I played my first chess of the year, getting together with Gjon Feinstein and Mike Splane and Juande Perea and Austen Green for speed chess. I had a very good time except for the fact that I kept losing on time. Five-minute chess is not my thing, especially yesterday. I kept getting “brain locks” […]

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How to Beat a Grandmaster

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Why Does Anybody Play 1. e4?

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