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| Apr-26-08 | | zenpharaohs: There are going to be a lot of ways to win. My first thought was 14 Rc2 Qb6
15 Rb1 Qc7
16 Qb4 Qxe5
17 f4 Qxe3+
18 Kh1 Re2
which sacs a lot of material but does win for White - the Queen is pinned and White has threats up the middle and on the Queenside. (Rybka 2.3.2a confirms the advantage) Rybka prefers
14 e6 Bxe6
15 Rc2 Qb6
16 Rb1
The game line
14 Qd4
is not so exciting.
14 Qd4 f6
15 exf6
is met by
15 ... Nxf6
16 Bxf6 Ne6
17 Qg4 gxf6
18 Bf5 Ke7
19 Bxe6 Rhg8
20 Qd4 Kxe6
21 Rb1 Qa3
22 Rxb7 Qd6
which doesn't look bad for White, but it's not busting the doors down. I'm sticking with Rc2, Rb1 immediately.
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| Apr-26-08 | | zenpharaohs: DualCore : "Either way you slice it, I really can't claim this puzzle, as e6 is inferior to Rc2 according to the computer analyisis posted. And I never even thought of Qd4." I don't know about that. I have set the problem for Zappa Mexico II on my fast Quad Core system which is the strongest engine I have. At the moment, it has searched 17 plies and it prefers Rc2 to e6 to Qd4. I'll check back in another hour or two. |
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| Apr-26-08 | | Marmot PFL: Black does not seem lost in the puzzle position (although worse). Unfortunately he plays as if completely unaware of the danger to his queen until it is too late to save her. |
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| Apr-26-08 | | dzechiel: White to move (14?). Black is a pawn up (presumably having just captured on b2). "Very difficult." Getting a late start today. I started watching the Dodger game last night and their ace closer gave up the tying run in the top of the 9th to make it 7 - 7. The Dodgers didn't push over the winning run until the 13th, and by then it was 'way past midnight. So, looking at this position I keep wanting to play
14 Nxd5
I have convinced myself that this is the key move, despite still not seeing the forced win. This move does recapture the pawn as well as threatens both 15 Nc7+ and 15 Rc2 picking up the black queen. For black to go pawn grabbing on b2 when he has not nearly completed development is one of the cardinal sins of chess. 14...cxd5
This seems to be the only immediate way out of black's mess. Now I have quite a list of candidate moves: - 15 Rc7
- 15 Qxg4
- 15 Qxa7
- 15 Bb5
Well, the longer I stare at this position, the less I am convinced that my first move was correct. My gut wants to make the move, but my brain can't support it. Other possibilities for first move would be 14 Rc2, but as that just sends the queen back to safety, I don't like it. I'm ashamed to say that I'm going to check the solution and see what I'm overlooking. Perhaps better luck tomorrow. =====
OK, this one was well above my pay grade. Congratulations to anyone who was successful in predicting the first move. |
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| Apr-26-08 | | johnlspouge: Saturday (Very Difficult): White to play and win.
Material: B vs. N+P. The Black Ke8 has no legal move. White is noticeably ahead in development. The White Qa4 shares a diagonal with Pc6, Bd7, and Ke8. It also attacks Ng4, which is protected only by Bd7. The White Bg5 is especially active, but Rc1, Nc3, and Bd3 are ready for action. The Black Qb2 is vulnerable to attack to gain tempi, but has escape squares. The only inactive White piece is Rf1, but even it blunts any threat on Pf2 from Qb2 and Ng4. White has no checks, so a forceful combination depends on a capture or a threat. Candidates (14.): Rc2
14.Rc2 (threatening 15.Rxb2)
If Black counterattacks on move 14...,
14…c5 15.Qxd7+ 16.Rxb2
dropping Bd2, so Black must retreat on move 14...
14…Qb6
I examined two lines seriously:
(1) 15.Qa3 (threatening 16.Qe7#)
The defenses 15…c4 16.Nxd4 Qe6 17.Nc7+ and 15…Ng6 16.Bxg6 both fail, obviously, so Black must resort to the anti-positional 15…f6 16.Rb1 Qd8
I cannot see through to refuting Black's play, but I would probably play this line over the board. With mate threats Nc7# and Qe7#, and with the pin on Pc6 almost permitting Nxd5 in the following line, I am sure there is something better. (2) 15.Rb1 Qc7 16.Nxd5 Qxe5 (threatening 17…Qxh7#)
The mate threat seems to permit Black to survive. It might be possible to repair the second line by forcing Ng4 to move at the right time with the move h3. One thing Wahls vs Yusupov, 1991 taught me last Sunday, however, is that Yusupov is presently beyond <my> pay grade. Time to peek. I am amazed at the completely unexpected first move. The threats evolved completely differently from my expectations. I have good company in my pay grade, however :) |
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| Apr-26-08 | | DarthStapler: I didn't get it, but the solution was very interesting |
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| Apr-26-08 | | wals: Static Evaluation: Looking at the board, as it stands, now.
White, down a pawn, efile doubled with isolated pawn en prise,
black, strong connected pawn structure on the queenside.
White has castled short.
White is up a bishop for a knight.
At move 13, who is in front, and by how much?
Dynamic Evaluation: The black King, not castled, could castle long.
White is more developed than black, rooks in position,
black's still in place, other pieces more active than blacks.
How to capitalise? Qa5, would prevent the King from castling.as Bg5 is doing.
It would also provide an opportunity for a mate on e7.
Bishopf4 would protect the e5 and e3 pawns.
Be2 would attack Ng4.
Abstract Assement: 14.Qa5 ...Ng6 15.Bxg6 ...0.0
PM=
No where near it. At move 13, white was in front, + 1.69pawns. Artur Yusupov - Jesus Nogueiras, Montpellier ct 1985
14.Qd4 was the second string according to Fritz.
Analysis by Fritz 11: Depth 20/42 time 6 min.
1.  (2.30): 14.Rc1-c2 Qb2-b6 15.Rf1-b1 Qb6-c7 16.Qa4-b4 Qc7xe5 17.f2-f4 Qe5xe3+ 18.Kg1-h1 h7-h6 19.Bg5-h4 g7-g5 20.Rc2-e2 Qe3xe2 21.Bd3xe2 g5xh4 22.Qb4xb7 2. (1.57): 14.Qa4-d4 f7-f6 15.e5xf6 Ng4xf6 16.Bg5xf6 Nf8-e6 17.Qd4-h4 g7xf6 18.Qh4xf6 Rh8-f8 19.Qf6-e5 Qb2-b4 20.Bd3xh7 Qb4-g4 21.Bh7-d3 Rf8-g8 22.g2-g3 Qg4-g5 23.f2-f4 (, 27.04.2008)
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Apr-26-08
 | | playground player: Did anybody solve this one--without using a computer? I hit upon a fool's approach--14.Bf4. |
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| Apr-26-08 | | zenpharaohs: After just about 5 hours, Zappa Mexico II on quad core values 14 Rc2: +3.01
14 e6 : +1.81
14 Qd4: +1.25
I'll let it keep running but I think it's made up its mind, and I agree with it. |
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| Apr-26-08 | | 234: Saturday puzzle <24. ?> Apr-25-08 Taimanov vs Lisitsin, 1949 |
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| Apr-26-08 | | littlefermat: Didn't solve it, but this was a nice puzzle. I looked at it early in the morning and mulled over it the entire day (this might be a good way to look at the Friday, Saturday and Sunday puzzles, btw). The salient feature of the position is that Black's king is stranded in the centre. Figuring out the right way to exploit it, however, was not quite so easy. My first choice was (breaking up the centre):
14: Nxd5 cxNd5.
15: Rc7 Bd7xQa4
16. Re7+ Kd8
17. Rb7
etc.
Doesn't give White anything.
Second choice (again, breaking up the centre):
14: e6 Nxe6
15: Rc2 Qb6
16: Rb1 Qc7
17: Bf4 Ne5
18: Nb5 Qb8
Doesn't yield much of a death blow.
So I eventually convinced myself that these moves give White nothing. Looking at the position some more, Black has some awkwardly placed pieces: Qb2 and Ng4. So I tried to see some way of exploiting this (hanging piece). I can't deflect the bishop at d7 (holding onto the knight at g4). So I ruled that out. So it must be the queen! Maybe we can trap it. 14: Rc2 Qb6
15: Rb1 Qc7
16: Qb4 Qxe5
Okay, I just don't see it. Best I can offer.
_____________________________
Ack, 14: Qd4 Silent move. With the threat of 15: Nxd5 QxQd4 and 16 Nc7 mate. Hats off to Yusupov.
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| Apr-26-08 | | Robin01: Tough puzzle -- enough said!:) |
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| Apr-26-08 | | randallbsmith: Hey <hms123>, what does Dvoretsky say about that Nb5 option? It was my first thought. Sac the knight to trap the queen, and even though it can kind of struggle out, I thought it still looked promising for white. |
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| Apr-26-08 | | zooter: <MaczynskiPratten: I missed Qd4 because I overlooked the key threat behind it; 15 Nxd5! Qxd4 16 Nc7#! I'm sure most other posters saw this - just mentioning it for completeness. So Black either has to move the Q or create an escape square for his K. He does this with f7 but then White's 17 Nb5! removes it by threatening Nd6# instead!> Thanks, I missed the first mate threat... |
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| Apr-27-08 | | znprdx: 14.e6 Bxe6 15.Rc2 Qb6 16.Nxd5 Bx[N]d5 17.Qx[N]g5 threatening Bd8 followed by Qxg7 |
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| Apr-27-08 | | znprdx: ...14f6? What is going on? Obviously Ne6 and White has nothing |
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| Apr-27-08 | | zenpharaohs: OK Zappa Mexico II has run for 10 hours, the valuations at 23 ply depth are: 14. Rc2: +3.32
14. e6 : +1.82
14. Qd4: +1.31
so Rc2 is even more attractive than at lower depth.
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| Apr-27-08 | | MostlyAverageJoe: <zenpharaohs: OK Zappa Mexico II has run for 10 hour> Did you get something similar to the line from my post on the 1st page? I am just curious whether Zappa found some improvements. |
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Apr-27-08
 | | patzer2: For the Saturday April 26, 2008 puzzle solution, White played the centralizing 14. Qd4!! to strengthen his position against the weak and undeveloped Black King position and exposed Queen. In the follow-up, the discovered attack 17. Nb5! exposes the double threat of mate (i.e. 17...Qxd4?? 18. Nd6#) or the loss of the Black Queen (e.g. as in the game continuation). As noted by <johnlspouge>, <Zenpharaohs> and <Zanshin>, 14. Rc2!! may be an even stronger winning alternative. |
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| Apr-27-08 | | 234: <FRIDAY> puzzle, not Saturday as I previously stated: < 234: Saturday puzzle <24. ?> Apr-25-08 Taimanov vs Lisitsin, 1949 > |
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| Apr-27-08 | | hms123: <randallsmith> Dvoretsky doesn't give any details about Nb5 but you will notice that Nb5 is played at move 17 threatening 17...Qxd4 18. Nd6# |
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| Apr-29-08 | | zenpharaohs: OK Here is the result of a long computation using Zappa Mexico II on a 2.66 GHz Quad Core: 23 1021:12 +3.13 14.Rc2 Qb6 15.Rb1 Qc7 16.Qb4 Qxe5 17.f4 Qxe3+ 18.Kh1 f6 19.Re2 fxg5 20.Rxe3+ Nxe3 21.Qxb7 Rd8 22.Ne2 gxf4 23.Nxf4 Kf7 24.Qxa7 Re8 25.Qc5 Ng4 26.Rf1 Nf6 27.Nh5 (51.355.362.509) 838 23 1337:00 +1.86 14.e6 Nxe6 15.Qxg4 Nc5 16.Qd1 Qa3 17.e4 Ne6 18.exd5 Nxg5 19.Re1+ Kf8 20.h4 h6 21.hxg5 hxg5 22.dxc6 Bxc6 23.Bb5 Kg8 24.Bxc6 (62.296.349.265) 776 23 1522:13 +1.34 14.Qd4 Ne6 15.Qxg4 h6 16.Bh4 g5 17.Bg3 h5 18.Qf3 h4 19.Qf6 Rf8 20.Bxh4 gxh4 21.Qxh4 Qa3 22.f4 Rg8 23.Kh1 Nc5 24.Bb1 Qb2 25.g3 (68.678.403.295) 751 So it looks like I solved this one.
This will run for another eight hours or so before I switch to the next one. |
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| May-01-08 | | zenpharaohs: It's still been running so I might as well post the final result. After 80 hours on the Quad Core: 24 3057:20 +3.17 14.Rc2 Qb6 15.Rb1 Qc7 16.Qa3 Qxe5 17.f4 Qxe3+ 18.Kh1 f6 19.Re2 fxg5 20.Rxe3+ Nxe3 21.Rxb7 gxf4 22.Na4 Rd8 23.Qd6 Ng4 24.Kg1 h5 25.Qxf4 Rh6 26.h3 Ne6 27.Qd6 (122.928.141.806) 670 24 3502:48 +1.90 14.e6 Nxe6 15.Qxg4 Nc5 16.Qd1 Qa3 17.e4 Ne6 18.exd5 Nxg5 19.Re1+ Kf8 20.h4 h6 21.hxg5 hxg5 22.dxc6 Bxc6 23.Bb5 Kg8 24.Bxc6 bxc6 (138.402.569.987) 658 24 3944:10 +1.35 14.Qd4 Ne6 15.Qxg4 h6 16.Bh4 g5 17.Bg3 h5 18.Qf3 h4 19.Qf6 Rf8 20.Bxh4 gxh4 21.Qxh4 Qa3 22.f4 Rg8 23.Bf5 Nf8 24.Qh5 (153.440.880.568) 648 Since all three lines have gained ever so slightly from 23 to 24 ply, it suggests that they all probably win for White, but obviously Rc2 is the highest valued of the three. |
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| May-04-08 | | MostlyAverageJoe: <zenpharaohs> Thanks. I find it quite encouraging that with some manual prodding, in about 5 minutes, I was able to produce a line that agrees in the first 14 plies with the 10-hour run of Zappa. MAJ+Hiarcs: (+3.25)
14. Rc2 Qb6 15. Rb1 Qc7 16. Qb4 Qxe5 17. f4 Qxe3+ 18. Kh1 f6 19. Re2 fxg5 20. Rxe3+ Nxe3 <21. Qd4> Zappa (23-ply) (+3.13)
14. Rc2 Qb6 15. Rb1 Qc7 16. Qb4 Qxe5 17. f4 Qxe3+ 18. Kh1 f6 19. Re2 fxg5 20. Rxe3+ Nxe3 <21.Qxb7> Note that the divergence occurs past the point where the infinity analysis is really reliable (which is generally 1/4 to 1/3 of the total ply count, or about 8 plies into the above analysis). For 24-ply run, the divergence occurs earlier; in fact, quite suprisingly earlier -- only 4 plies into the line. Curious. Zappa (24-ply) (+3.17)
14. Rc2 Qb6 15. Rb1 Qc7 <16. Qa3 Qxe5 17.f4 Qxe3+ 18.Kh1 f6 19.Re2 fxg5 20.Rxe3+ Nxe3 21.Rxb7> |
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| Mar-24-09 | | Dredge Rivers: Chessplayer, heal thyself! :) |
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