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Jun-12-10
 | | OBIT: Just for the fun of it, would anyone with Fritz or Rybka like to try the following position?
It is White to move. See if the bot gets the right answer:
click for larger view |
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Jun-12-10
 | | Sneaky: <Peligroso Patzer: <Sneaky: Please note...
click for larger view
WHICH IS A DRAW!! Anytime White gets the nerve to try Kxb8 then Black immediately plays d1=Q, game drawn. Poor Byrne, he resigned when he could have salvaged half the point. *** >
The foregoing analysis is <not correct>.> Thank you for pointing that out, I tried to help clarify what's going on in this position last night, but now I find myself retracting virtually every single point I made. That means it that nobody resigned inappropriately in the game either--the final position really is 1-0. <Tablebases (http://www.k4it.de/index.php?topic=...) verify that the above-diagrammed position from the post by <Sneaky> is 1-0 with either side to move. Black to move is in zugzwang; White to move wins with Bishop tempo moves along the d1-h5 diagonal until he can play Be2 when Black's King is on a5.> I certainly am not going to argue with tablebase, but at first I still didn't see it. Now I'm pretty sure I do. At some point White has to play a waiting move like Bf3 or Bh5, then when Black plays Ka5 White responds with Be2! cutting off the king--and if the king can't move the bishop has to move, and if the bishop moves it's time for a7 and a8=Q. Good problem, it's got more layers than an onion. |
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| Jun-12-10 | | Once: <OBIT: Um, any chance this is just human error?> I think the only human error today is trusting engines a little too much! I'm running Fritz 11 without tablebases installed and he needs to be shown the win several moves on from the puzzle position. So, yes, at least some of the computers were fooled by today's position. There's hope for humanity yet. The ones with rubber skin we could spot pretty easily. But then came the HKs. We were that close to going out. Then John Connor helped us to turn it around. Skynet was smashed ... Oops, sorry. Got a little carried away there.
But an entertaining puzzle today, yes? |
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| Jun-12-10 | | David2009: R Calvo vs D Byrne, 1968 White 68? 68 Be2 Bd6 69 b8=Q Bxb8+ 70 Kb7 and astonishingly Black is in zugzwang and cannot in the long run prevent a7. One variation:
70...g4 71 Bxg4 Kb5 72 Bd1 Ka5 73 Be2 d1=Q 74 Bxd1 Kb5 75 Bg4 Ka5 76 Be2 and Black has no spare Pawn moves so must move either his King (losing the B) or his B (allowing promotion). Amazing!
Time to check:
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Close enough. Time to enjoy the game and others' comments. |
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Jun-12-10
 | | Phony Benoni: Perhaps the problem is that engines have gotten us accustomed to solving puzzles by exact analysis. Today, the important points are to spot the zugzwang-like possibilities after 1.b8Q and 2.Kb7, and to realize these can be re-established by temporizing moves with the bishop. Once this is done, the exact order of moves is irrelevant; there are probably dozens of paths to victory. Trying to calculate an exact path can lead to spinning the mental wheels--as several excellent players have shown us. |
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| Jun-12-10 | | David2009: <OBIT: Just for the fun of it, would anyone with Fritz or Rybka like to try the following position? It is White to move. See if the bot gets the right answer:>
click for larger view
Crafty allows White to win starting 1 Qxg6 fxg6 2 Kg1 but I don't know if this is best defence - Black wants to be able to play Ne6 with check but can't quite do it. OBIT - what should happen? Crafty link: http://www.chessvideos.tv/endgame-t... |
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| Jun-12-10 | | Eduardo Leon: <David2009>, interesting position. Black, two pieces and two pawns ahead, is completely lost. <1.♕xg6 fxg6>
What else? If 1...♘xg6, then 2.♖xh7# is mate.
<2.♔b1 ♗c4>
Black's remaining pieces are tied to their places. This bishop can only switch between c4 and d5, since 2...♗(other) allows 3.♘f7#. And 2...♗e4+ 3.♔c1 ♗d5 just transposes. <3.♔c1 ♗d5 4.♔d2 ♗c4 5.♔c3 ♗d5 6.♔d3!> Not 6.♔d4? ♘e6+ 7.♘xe6 ♖(any).
<6...♗c4+ 7.♔xc4 ♘(any) 8.♘f7#> More elegant than 8.♖xh7#. |
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| Jun-12-10 | | dumbgai: Just to be sure: 70. Bh5 and Bf3 work just as well as Bg4 right (waiting moves)? |
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| Jun-12-10 | | sethoflagos: <OBIT:> I would only add to <Eduardo Leon>'s analysis that black's bishop can use e6 and a triangulation may be required to capture it: 1. Qxg6 fxg6
2. Kb1 Be4+
3. Kc1 Bd5
4. Kd2 Be6
5. Kc3 Bd5
6. Kd3 Be6
7. Kd4 Bc4
8. Kxc4
Another (longer) forced win is available by releasing the a-pawn 6. Kb4 Be6
7. Kxa4 Bd5
8. Kb4 Be6
9. a4 Bd5
10. a5 Be6
None of my engines (Rybka 3/Fritz 12/Crafty 23/Comet B68) can see beyond the trivial draw by repetition to the win and need to be walked through. Comet was quickest on the uptake. |
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| Jun-12-10 | | cjgone: I see that its forced win for white sooner or later. I didn't choose the same bishop move, I chose bf3.. I don't think it matters though since it's forced anyway. |
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| Jun-12-10 | | iamsheaf: Somehow, Mr Byrne has a tendency of being at the receiving end of a good game. |
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| Jun-12-10 | | iliekchess: Can someone please post a concrete line that wins? |
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| Jun-12-10 | | SufferingBruin: Today, I had to pass on a chess tournament because I'm allergic to cats. I'm extremely upset about this. It's kind of like pulling out of a basketball game because you have a hangnail but there it is. So, forgive me for not scrolling through the comments (which I usually love to do) but if you can humor me by answering this question: Do I get credit for the move Be2? Or do I count this as a miss? Thanks in advance. Now, if you'll excuse me, I'm off to an allergist... |
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| Jun-12-10 | | CHESSTTCAMPS: <Peligroso Patzer:> <To pick one final nit re: today’s puzzle, the assertion that 68. Be2 is more accurate than Calvo’s move..> An interesting suggestion, but I believe that the tempo gained by avoiding the trangulation maneuver (Bd1-g4-e2) is given back in the continuation 68... Bb6+ 69.Ka8 Bc7 because white makes an extra king move. |
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| Jun-12-10 | | CHESSTTCAMPS: <SufferingBruin:> <Do I get credit for the move Be2? Or do I count this as a miss?> No credit unless you see the necessity to follow up with b8=Q Bxb8 Kb7!! Good luck with the allergist! |
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| Jun-12-10 | | CHESSTTCAMPS: <iliekchess:> < Can someone please post a concrete line that wins?> From the puzzle position 68.b8=Q! Bxb8+ 69.Kb7! Kb5 70.Bg4 Here Byrne resigned. If now 70...Ka5 (or Kc5 met by same response) 71.Be2 and now: A) 71... Ba7 72.Kxa7 followed by 73.Kb7 and the a-pawn promotes. B) 71... Bc7 (or Bd6, Be5, etc) 72.a7 and the a-pawn promotes. C) 71... Ka4 or Kb4 72.Kxb8 and the a-pawn promotes.
D) Black drags it out as long as possible.
71... g4 72.Bxg4 Kb5 73.Bf3 (required waiting move a.k.a triangulation maneuver) Ka5 74.Be2 d1=Q 75.Bxd1 Kb5 76.Bf3 (waiting move) Ka5 77.Be2 and now black must choose one of the options A, B or C. 77...Bf4 78.a7 any 79.a8=Q and the ending is easily won. I hope this works for you. |
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| Jun-12-10 | | SuperPatzer77: < Eduardo Leon: <David2009>, interesting position. Black, two pieces and two pawns ahead, is completely lost.
<1.Qxg6 fxg6>
What else? If 1...Nxg6, then 2.Rxh7# is mate.
<2.Kb1 Bc4>
Black's remaining pieces are tied to their places. This bishop can only switch between c4 and d5, since 2...(other) allows 3.Nf7#. And 2...Be4+ 3.Kc1 Bd5 just transposes. <3.Kc1 Bd5 4.Kd2 Bc4 5.Kc3 d5 6.Kd3!> Not 6.Kd4? Be6+ 7.Nxe6 R(any).
<6...Bc4+ 7.Kxc4 N(any) 8.Nf7#> More elegant than 8.Rxh7#.>
Yeah, it is very interesting. 6. Kd3! (only move for a win) Be6 (instead of Bc4+), 7. Kd4! (now Black is in complete zugzwang because the Black Bishop is unable to escape) Bc4, 8. Kxc4 (now forcing mate)  SuperPatzer77 |
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| Jun-12-10 | | zanza: Chapeau! What a beautiful idea, for winning an opposite bishop endgame! |
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| Jun-12-10 | | tacticalmonster: 1) d2 pawn is useful in diverting the LSB`s protection of a6 pawn with d1=Q 2) White has to give up the b7 pawn for the DSB while retaining the a6 pawn 3) Black d2 and g5 pawns are not dangerous without the support of their king. They are also solidly restricted by the LSB 4) White should try to overload Black on the a7-g1 and the b8-h2 diagonals Candidate: 68 Be2
68 Bb6+ 69 Ka8 Bc7 30 b8=Q! Bxb8 31 Kb7! g4 32 Bxg4 Kb5 33 Bd1 Ka5 34 Be2 d1=Q 35 Bxd1 Kb5 36 Be2+ |
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| Jun-12-10 | | tacticalmonster: The reason this bishop of opposite colour is a special case is because of the rook pawn. Black can only use h2-b8 diagonal and the a7-b8 diagonal to stop the pawn. Notice the a7-b8 is extremely short. If you put a pawn on, lets say, e7 square, the defender can blockade the e8 square on the e8-h5 and a4-e8 diagonal. Both diagonals are long. Conclusion: In bishops of the same color or opposite color it is generally better to have the wing pawns than the center pawns. One extra feature you have to watch out for is whether the bishop is on the same color as the corner of the rook pawn. |
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| Jun-12-10 | | tacticalmonster: Another reson why is because of the activity of the two kings. White king is much more active than his counterplay. In fact, king position is so important in opposite color bishop ending it is more important than an active bishop. Switch the color of both king and we have a dead drawn position. Better pawn structure is usually not a superior asset for the winning side. The rule is: The further apart the passers the more winning chance the stronger side has. Therefore, White connected passer alone in the game is not stronger compared to black passers. What makes them stronger is they are way further advanced than black passers. |
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Jun-13-10
| | OBIT: <sethoflagos><Eduardo Leon><david2009>Thanks for participating in my little experiment, guys. Seth has the continuation I had in mind, which is maneuvering the king to force the Black bishop to e6, then playing Kd4, when ...Ne6 is not possible. Seth also points it is possible to win by capturing the a-pawn. That second solution wasn't my intent, although I can fix it easily enough by removing the pawns on the a-file. It's interesting to me, though, that none of the bots find either win. They do at least see that 1. Qxg6 is good for a draw despite being down quite a bit of material. So, the concept of a blockaded position isn't foreign to them. However, these triangulation tricks to set up a zugzwang seem to give them a lot of trouble. The bishop can be captured in at most seven moves, and, since Black has only one piece he can move, it seems like a bot should have no problem analyzing at least this far. But, nope, it seems they can't figure out how to reach the key position. |
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Jun-15-10
 | | scormus: <Jim> 63 b7 perhaps? |
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Jun-15-10
 | | Jimfromprovidence: <scormus> I think it is a win now after 63 b7. 63...Bc7 is forced to prevent Kb6, creating a path for the a pawn. Now comes 64 Bd7! 
click for larger viewI think this is it in essence. Black either has to move his king away from the a pawn, allowing Ka7 and thereby soon connecting the two pawns or play 64 d2, after which white will play 65 Bg4. If black plays 65...Ka4, white will shuffle his bishop along the diagonal until black has to play ...Kb4, then white will pounce with Bd1, like in the diagram below. 
click for larger view |
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Jun-16-10
| | scormus: <Jim> thanks. Neat play with the WB |
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