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| Jul-05-12 | | ventricule: This one is quite tough for a thursday in my opinion. I figured out the underpromotion (but no way I would have been careful enough to spot it on the board !), and a bishop looked like a better choice than a knight. Then I found that the only possible plan was to bring it on f7 via d5, so the next moves were pretty forced as well. But I started to get worried there, it looked like there was no choice but to exchange the queens, and then no way to gobble the pawns ! The real shocker one has to see is 68. Kg6. It's no stalemate but cruel zugzwang and wins on the spot. All my respect for the fellow kibitzers who solve the problem up to this point ! |
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Jul-05-12
 | | Patriot: Wow, so 61.a8=Q Qf7+!! 62.Qxf7 stalemate. It appears that 61.a8=B may be the win. 61...Qxa8?? 62.Qxa8 and black still has a move (62...g6+). Play might continue, 61.a8=B Qb3 62.Qd8 (preparing 63.Bd5 and mate next). Also there is a swindle attempt: 61...g6+ 62.Qxg6+ Kh8 63.Bxb7?? draw. But 63.Qxh6+ Qh7 64.Qxh7+ Kxh7 65.g5 should win easily. Much better is 63.Qe8+ and 64.Bxb7. |
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Jul-05-12
 | | Phony Benoni: <Patriot> 61.a8B Qb3 62.Qd8 is a very effective way of avoiding the draw by stalemate after ...Qf7+. Perhaps too effective. |
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Jul-05-12
 | | Jimfromprovidence: <Phoni Benoni> 6<1.a8B Qb3 62.Qd8 is a very effective way of avoiding the draw by stalemate after ...Qf7+. Perhaps too effective.> Yes. 62...Qf7# avoids stalemate.
It's also important to note that 61...Qb3 is the only move that black has to avoid an immediate forced mate after 61 a8B because of the 62 Bd5 threat. |
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| Jul-05-12 | | TheBish: A Reshko vs O Kaminsky, 1972 White to play (61.?) "Medium"
With underpromotion week continuing, we notice that after 61. a8=Q or 61. a8=R Black plays 61...Qf7+! 62. Qxf7 stalemate. Also, after 61. g5?? Qf3#. So the underpromotion piece is logical, if we combine these factors. 61. a8=B!
After Black moves his queen, White will play either Ba8-d5 with unavoidable mate, or (in the event of 62...Qb3) play Ba8-c6-d7-e6 with the same mate to follow on g8, or Black will be forced to trade queens (by 64...Qg8), leaving White with an easy endgame win. |
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Jul-05-12
 | | Moonwalker: Got it! And by that I mean I saw the stalemate if 61. a8=Q/R. This leaves promotion to a bishop and the rest of the game is history.
I'm surprised black played for as long as he did! |
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Jul-05-12
| | Patriot: <<Phony Benoni>: <Patriot> 61.a8B Qb3 62.Qd8 is a very effective way of avoiding the draw by stalemate after ...Qf7+. Perhaps too effective.> You're right! I forgot about the mate threat! |
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Jul-05-12
 | | scormus: <Sneaky ....a lie ... say it isnt so> It's not really a lie, just what is known in literature as "elegant variation." We've already had 2 underpromotions to N (my comment yesterday <Oh no, not promotion to N again>). I must admit, I did wonder about a8=N but decided the win would be more difficult. I would guess 61 ... Qa7 and W has a lot of fiddling about to do. If W actually does win ..... |
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Jul-05-12
 | | chrisowen: Concern with under-promotion I'd emphasise straight away in would effervescent knight it spring in QR1 surrounded kings very little maneovering to be done so seeing as queen promotion results in us drawing fire on f7 and stalemate I think idea for queen shunt and demonstrate ability racking up personal favourite bishop promotion over knight inkling to persevere fortress established by both given time it manage white win for extra piece counting long-rendezvous clean cut principle knock out blow dont see but happy finding combination staving off stalemate ie queen flogging grave and proud for Reshko completion under-time picking right continuation instructive bishop it this mean incision more effective in common mind also going knight not as resourceful bigger gap in leap to coordinate ok some chances black to accrue salvage draw method white overall sufficient dispatch accumulate precise transformation ending initial right moment it. |
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| Jul-05-12 | | LoveThatJoker: <61. a8=B!>
Only move as 61. a8=Q?/a8=R? Qf7+ 62. Qxf7 is stalemate. <61...Qb3>
So as to prevent 62. Bd5.
<62. Bc6>
The plan is to manoeuvre the B to the e6 square via Ba8-c6-d7-e6 - unfortunately for Black, he has no real way to prevent this. <62...Qc4>
[62...g6+ 63. fxg6+ Kg7 64. Qe7+ Kg8 (forced) 65. Kxh6 Qe3+ 66. Qxe3 mating] <63. Bd7 Qc7>
(63...g6+ 64. Kg7 Qe7+ 65. Kg8 Be6+ 66. Qxe6 Qxe6+ mating) <64. Be6 Qd8>
(64...g6+ 65. fxg6+ Kg7 66. Qg8#; 64...Qf7+ 65. Qxf7 Kh8 66. Qg8#) <65. Qxd8 g6+ 66. fxg6+ Kg7 67. Qg8#> LTJ |
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| Jul-05-12 | | SamAtoms1980: After 61.a8=Q or 61.a8=R, Black will play 61....Qf7+ and draw by stalemate. So White promotes to a bishop, and the jig is up. |
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| Jul-05-12 | | LoveThatJoker: Full point for today - admittedly however, it would have been more thorough of me had I noted what transpires if 62...Qg8 63. Qxg8 Kxg8 64. Kg6. This said, it is understood that in my answer I placed the emphasis on finding direct counterplay for Black than on entering a totally lost endgame. It is important to note however that there are some visually interesting and didactically rich tricks in the following endgame: 61. a8=B Qb3 62. Bc6 Qg8 63. Qxg8 Kxg8 64. Kg6 Kf8
Analysis Diagram - Position after 64. Kf8
click for larger viewAlthough clearly 65. Bd5 is the best move in this position, let's say that here White got filled with both impetuosity and indignation that Black was playing on and went in for the impulsive simplifying line 65. g5 hxg5 66. hxg5 fxg5 67. Kxg5 Kg8 68. Kg6 Kh8 
click for larger view<Important Position> It is a win for White, but it requires tactical care. LTJ |
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Jul-05-12
 | | sevenseaman: An under-promotion to a B leaves no resource to Black. If it is to a Q or a R 61...Qf7 stalemates as White needs to take f7, (being a check). I have not exactly figured out what happens if its to a N. The stalemate will definitely be avoided but my apprehension is White could throw away his win in the bargain. The N will have to be brought to bear on f7 and that will involve some work(therefore a greater chance of a mistake). My line works out to;
<61. a8=B Qb3 (to prevent 62. Bd5)62. Qd7 Qg8 63. Bd5 Qf8(best) 64. Bf7 Kh8 65. Qe8 Qxe8 ( If 65. Kh7 66. Bg6+ Kh8 [if kg8 67. Bh7+ et al] Kxh7 67. Qxf8 and Black has to move a P now) 66. Bxe8 Kh7 67. Bf7 Kh8 68. Kg6 h5 69. Kxh5 Kh7 70. Be8 Kg8 71. Kg6>, leaving Black K the doltish option of oscillating between f8 and h8 while White work his Ps to win. |
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| Jul-05-12 | | poszvald: I think its ok to get a bishop, to prevent stealmate. |
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Jul-05-12
| | sevenseaman: It might be only a Thursday but my work on the POTD took me 1 1/2 hour today. Guessing it was an u/p to a B wasn't too difficult but working out the line in detail was very elaborate. So overall it was tough for the day. If difficulty rises in a linear manner then we should have some work on our hands in the week end. |
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| Jul-05-12 | | gofer: <Once> you notice that <61 a8=Q Qxa8 62 Qxa8> isn't stalemate the only
threat black has is getting a stalemate via <61 a8=Q Qf7+ 62 Qxf7>, then
we are free to promote to anything except a rook or queen, but what is
going to better?
61 a8=N Qa7! (The knight is trapped!)
62 g5 hxg5
63 hxg5 fxg5
64 Qg6+ Kh8
65 Nb6 
This is probably winning for white but its a hard slog! <61 a8=B ...>
I confess I don't see a quick finish, but its probably there... ~~~
Yep! |
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Jul-05-12
 | | tarek1: I chose to under-promote to knight.
Probably it's easier to win with a bishop but I have a hard time believing it's not a win for white anyway. |
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| Jul-05-12 | | Deji: Yessss, under-promote. I missed that completely |
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Jul-05-12
 | | agb2002: White is a pawn ahead.
Black threatens 61... Qxa7.
61.g5 is a very bad idea due to 61... Qf3#.
After 61.a8=Q(R) Qf7+ forces the stalemate. This suggests 61.a8=B with the idea Bd5-Qg8#: A) 61... Qb3 62.Bc6 (62.Qd8 Qf7#; 62.Qe6 Qxe6 63.fxe6 g6#) and Black can't stop the maneuver Bd7-Be6. B) 61... g6+ 62.fxg6+ Kg7 63.Qf7+ Qxf7 64.gxf7 Kxf7 65.Kxh6 + -. |
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Jul-05-12
 | | whiteshark: Got it <at 4.9 sigma confidence level!> |
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| Jul-05-12 | | handro1104: Why could't black play 61...QXa8? |
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Jul-05-12
 | | kellmano: <handro1104: Why could't black play 61...QXa8?> He could do, but when White takes the Queen it's not stalemate. |
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| Jul-05-12 | | LoveThatJoker: <handro1104> 61. a8=B! Qxa8 62. Qxa8 g6+ (forced) 63. fxg6+ Kg7 64. Qe8 (64. Qb7+ also mates) 64...f5 65. Qf7+ Kh8 66. Qh7# LTJ |
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Jul-05-12
 | | paire: Great puzzle... not decisive victory, but still just enough :) It was fun working it out. |
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Jul-05-12
 | | Abdel Irada: <Tricks and treats> In this tactically rich queen-and-pawn ending, White must watch his step. There are different kinds of "mate," and it is necessary to avoid the "self-" (more accurately, "help-") and "stale-" varieties. If, for example, White tries to get pushy in quest of mate on the kingside with <61. g5??>, he finds the very worst kind of mate: <61. ... f3#> does the trick. Equally bad is the attempt to "escort" the pawn, <61. b1??>, which runs headlong into <61. ...f7#>. More plausibly, White queens (or rooks) the pawn. Here, at first glance, Black appears hopelessly lost. This impression lasts exactly one ply: <61. a8=/a8= ?, f7+; 62. xf7, stalemate>. Therefore, White must keep his queen observing f7 and promote the pawn to a non-horizontally moving piece. The most plausible line goes something like this: 61. a8= !, b3 (White hopes to infiltrate with d5, and this is the only available move that prevents it); 62. d7 (This pins the g-pawn and takes control of d5. Here White must avoid another trap: <62. e6??, xe6; 63. fxe6, g6#>), b8 (This prevents mates on g8 while leaving the queen some freedom of movement, and I therefore rate it best); 63. d5, f8 (Similar variations follow <63. ...h8>); 64. f7, b8 (Similar is <64. ...a8>; much worse is <64. ...h8?; 65. g6+,  g8; 66. e8#>); 65. g6+, g8 (Quite similar is <65. ...h8>); 66. f7+, h8;
67. e8+, xe8;
68. xe8, h7;
69. f7!, h8;
70. g6!, h5;
71. g5!, fxg5;
72. hxg5, h4;
73. f6, gxf6 (<73. ...h3??; 74. fxg7#>); 74. gxf6, h3;
75. d5, h2;
76. f7, h1=/any;
77. f8=#/f8=#.
There may be a more efficient winning line that I have overlooked, but I rather like this finish. |
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sac: 24.e6