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| Nov-06-10 | | ruzon: I'm with <dzechiel>, only I didn't consider Rdd7 in the first place. Too many non-forcing moves for me. |
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Nov-06-10
 | | Phony Benoni: OK, I think the key may be considering what happens in this position, after <44...Ra1+>
click for larger view
White cannot play 45.Kd2/e2 because of 45...a2. Now 46.Rdd7 Rd1/e1+ and Black promotes, or 46.Ra7 Rh1! setting up the skewer trick 47.Rxa2 Rh2+. 42.Rdd7 avoids this possiblity because White now has d3 for his king after 42...Ra1+ 43.Kc2 Ra2+ 44.Kd3, and White gains a tempo since 44...Ra1 is not check; White can answer 45.Ra7 before the pawn goes to a2. If Black tries 44...Rh2 (etc.), White now plays 45.Rxf7 a2 46.Rxg7+ Kh8 47.Rcg7+ Kf8 48.Ra7. This analysis may be a bit sloppy and there may be some more ideas to find, but I think this is on the right track: White has to clear d3 for his king. |
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Nov-06-10
 | | OBIT: Like <dzechiel> and others, I want to play 42. Rxf7, but I think <Phony Benoni> is correct about why this move does not win. The king can't escape the perpetual by going to d2 or e2 because of the skewer trick (...a2 and if Ra7 Rh1). So White plays Rdd7 to vacate d3, allowing the king to escape via the route Kc2-d3. |
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| Nov-06-10 | | patzer2: I could find nothing better than 41. Rxf7 when trying without the computer. However, working it out move-by-move with Fritz 8, gives 42. Rdd7! Ra1+ [42... Bb2+ 43. Kd1 Kg8 (43... Ra1+ 44. Ke2 Kg8 45. Ra7 Bc3 46. Kd3 Bg7 47. Ra8+ Kh7 48. Rxf7 a2 49. Raa7 Rd1+ 50. Kc2 a1=Q 51. Rxg7+ Kh8 52. Rh7+ Kg8 53. Rxa1 Rxa1 54. Rxh6) 44. Ra7 Ra1+ 45. Kd2 a2 46. Ra8+ Kg7 47. Rda7  ] 43. Kc2 a2 44. Ra7 Rf1 45. Rxa2 Rf2+ 46. Rd2+ (+2.56 @ 18 depth). |
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| Nov-06-10 | | handro1104: What is wrong with 42. Ra7 followed with b4? |
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Nov-06-10
 | | scormus: Neat puzzle, which certainly had me foxed.
After 42. Rdd7 the BB remains menacing, therefore Rxf7, and I thought B would have to relieve the pin with ... Kg8 and then W could win (I guess - endings are not my thing) after Rxg7+. I should have realised that if B kept +ing the WK had to stay within striking distance of a1. I'll console myself that I mostly followed <Dzechiel's> thinking ... which is no disgrace. |
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| Nov-06-10 | | Once: It has taken some time, but with <phony benoni>'s and Fritz's help, I think I have worked out what is going on here. White doesn't have an immediate mating or material winning tactic. His goal is to prevent black from promoting his a pawn or giving perpetual check. So we need to examine black's plans rather than white's. And there are three standard devices in situations like this. The first is to get the passed pawn to a2, then sac the rook to get the king to the first rank and queen with check, like this: 
click for larger viewNow 1...Re1+ 2. Kxe1 a1=Q+ is drawn.
Or black plays for the skewer trick, like this:
click for larger viewNow 1...Rg1 or Rh1 protects the pawn indirectly because 2. Rxa2 Rg2/ Rh2+ followed by 3...Rxa2. The third trick for black is the perp with Ra1+ and Ra2+. For white to win he needs to avoid these three black defences. And to do that he needs to get onto the third rank (to avoid the Ra1/Ra2 perp) and to get there via c2 (so that black can defend against the Rh1/Rh2+ skewer trick with Rd2). And he needs to have the option of playing Rd2 or Ra7, depending on whether black tries the skewer trick or the rook sac trick. And to do all of that, white needs to clear the d3 square to allow his king to play Kc2-Kd3. And that brings us to 42. Rdd7. How does white win from here? I had no idea when I first solved this in human mode and having played with Fritz for a while I still have no idea. The win is still a long way away. But 42...Rdd7 is the only move not to allow black the draw, and that has to be a good thing. Tough but satisfying when you get it. |
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| Nov-06-10 | | goodevans: Thanks, <Once>, for the comprehensive explanation. First avoid the draw, then you can think about winning. Very logical! I would never have got this, but perhaps now I would if something similar emerged. Whenever I fail at the CG.com puzzle I always console my self with the easier puzzles found here: http://www.chessvideos.tv/chess-puz... |
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| Nov-06-10 | | Once: <goodevans: I would never have got this, but perhaps now I would if something similar emerged.> I think that's the right attitude to bring to puzzles like these. I chose 42...Rdd7 in my initial human mode analysis, but it was more of a pragmatic choice than a clear-cut decision. It was the only move I could find that didn't quickly lose or draw. So with the clock ticking, let's play it and worry about the consequences later. If this was a game, we need to watch that we don't lose on time. And as this is kibitzing, time to think about a story... Then I looked at the solution and <phony>'s excellent post and I started to worry at the problem like a terrier with a bone. Why was it that Rdd7 worked and Rxf7 didn't? I fired up the germanic genius (Herr Fritz) and stepped through lots of variations. All the time, trying to learn, understand, probe. I couldn't claim anything like a full understanding of 42. Rdd7 in human mode, so how do I improve for next time? I suppose that the puzzles that we spot in a heartbeat are the ones that don't teach us anything. We only learn when we have to work at a puzzle and tease out its secrets. It's a funny thing. I used to look forward to the ego-boost that is Mondays. Now I look forward to the learning experience that is the weekend. And the puzzles I really enjoy are those that, initially at least, I don't understand. |
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| Nov-06-10 | | sethoflagos: <Once:...<But 42...Rdd7 is the only move not to allow black the draw>>
It's perhaps worth noting that in the puzzle position black is also threatening .. 42.. Rf2 43 Rxf7 a2 44 Ra7 a1=Q 45 Rxa1 Bxa1
.. which while still looking drawish at least puts the boot on the other foot. |
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| Nov-06-10 | | David2009: S Vokarev vs S Azarov, 2008 White 42? White can liquidate into a better ending with 42 Rxf7 intending Rxg7 in most lines.
(A) 42...Rh1+ 43 Kc2 a2 44 Rxg7+ Kxg7 45 Kb2 winning easily
(B) 42...Rf2 43 Rxg7+! (not 43 Rd7? Rc1+ with perpetual check/ Rook skewer: if White tries to escape the checks by Kc2, Kb1, Ka2?? then...Ra1#) Kxg7 44 Kb1! and wins
But NOT 44 b4?? a2 46 Ra3 Kf6 etc and White is struggling to draw: White's King is paralysed and in zugzwang so White only has Rook moves).
Time to check/ set up on Crafty End Game Trainer
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Missed the other perpetual check - I have found the game continuation! 
click for larger view Crafty EGT link to the puzzle position as above
http://www.chessvideos.tv/endgame-t...
The only other plausible try is 42 Rdd7 which the EGT meets with Be5 drawing comfortably. One line: 42.Rdd7 Be5 43.Ra7 Kg8 44.Rxf7 Bd4 45.Rfe7 (to guard against Be3+ etc) Kf8 46.Rf7+ Kg8 47.Rfe7 Kf8 drawn by repetition. White has good losing chances if he overpresses. I give up. Time to read the note.
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The note confirms Rdd7 as the only winning try. Other kibitzes do not cover Crafty EGT's defence of Be5. Perhaps someone will find a win against the EGT and post it. Meanwhile other priorities call. |
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| Nov-06-10 | | kramputz: This is a puzzle from "Loony Land"
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| Nov-06-10 | | stygian: I chose 42.Rxf7. I was looking at a later Ra7 and b4 to further hone in on the a pawn. Right or wrong, I would probably have played the same over the board. The thing that struck me as important was the number of moves it would take Black to queen as opposed to the number of moves for White to cover. |
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| Nov-06-10 | | ReikiMaster: This is a tough puzzle if you only look at the diagram. It's much easier when you note that white has just diverted from a repetition and thus must see a win. Clearing d3 for his King is the only try. |
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| Nov-06-10 | | Keith Dow: Dear David2009,
"42.Rdd7 Be5
43.Ra7 Kg8
44.Rxf7 Bd4
45.Rfe7 (to guard against Be3+ etc) Kf8 46.Rf7+ Kg8 47.Rfe7 Kf8 drawn by repetition. " I won with:
42.Rdd7 Be5
43.Ra7 Kg8
44.Kd1 Bc3
45.Rd8 Kg7
46.Rd3 Bb4
47.Rd7 Kf6
48.Rxf7 Ke6
49.Rh7 Kd5
50.Ra4 Kc5
51.Rxh6 Rd2
52.Kc1 Rd3 |
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| Nov-06-10 | | Patriot: I saw that black was threatening 42...Rh2, 43...a2, and 44...a1=Q, and so the move I wanted to play (42.Rdd7) looked very dangerous for white. Therefore I decided on 42.Rxf7. For instance, 42...Rh2 43.Rxg7+ Kxg7 44.Kb1 safely stops the pawn. Or 42.Rxf7 Kg8 perhaps 43.Ra7. The recommendation 42.Rdd7 looks very interesting. I'll have to look at this further. For example, 42...Rh2 43.Rxf7 a2 44.Rxg7+ guarantees at least a draw. On 42...Re2 43.Rxf7 a2 44.Rxg7+ Kh8 45.Rh7+ Kg8 46.Rcg7+ Kf8 47.Ra7 looks like a winner for white. |
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Nov-06-10
 | | Jimfromprovidence: I saw 42 Ra7 (pinning the black rook), followed by 42..Rf2 43 Rd2!, below. (Not 43 Rxa3 because of 43…Bb2+!).
click for larger view
Now comes 43…Bb2+ (protecting the pawn) 44 Kc2 Rxf3 45 b4 and white has a little something going on.
click for larger view |
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| Nov-06-10 | | kevin86: At first,I thought white was lost-and my move to try to salvage an attack WAS Rdd7! Funny how it works;the right move for the wrong reason. The text allowed black to draw by perpetual check. |
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| Nov-06-10 | | rapidcitychess:
click for larger viewHoudini_w32_8CPU:
[d=25]+2.14 42.Rdd7 Ra1+ 43.Kc2 a2 44.Ra7 Rf1 45.Rxa2 Rf2+ 46.Rd2 Rxf3 47.Ra7 Rc3+ 48.Kd1 Rxb3 49.Rxf7 Kg8 50.Rd7 Bf8 51.Rf6 Rb8 52.Rg6+ Kh8 53.Rf7 Rd8+ 54.Ke2 Rc8 55.Kf2 Rb8 56.Kg2 Rb2+ 57.Kf3 Rb3+ 58.Ke4 Rb8 59.Kd4 Rc8 60.Kd5 Rd8+ 61.Ke4 Rb8 62.Kd4 |
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| Nov-06-10 | | David2009: <Keith Dow: Dear David2009, "42.Rdd7 Be5 43.Ra7 Kg8 44.Rxf7 Bd4 45.Rfe7 (to guard against Be3+ etc) Kf8 46.Rf7+ Kg8 47.Rfe7 Kf8 drawn by repetition. " I won with: 42.Rdd7 Be5 43.Ra7 Kg8 44.Kd1 Bc3 45.Rd8 Kg7 46.Rd3 Bb4 47.Rd7 Kf6 48.Rxf7 Ke6 49.Rh7 Kd5 50.Ra4 Kc5> to reach 
click for larger view Congratulations! The key move is 44 Kd1! tying the Black Rook to defend the a Pawn. I also like 50 Ra4! keeping the Black King out. Presumably you finished Crafty EGT off with 51.Rc7+ Kb6 52.Rc2 Rxc2 (a pleasant surprise, but what else?) 53.Kxc2 Kb5 54.Kb1 Be7 55.Ka2 and the Black pawns start to fall like ripe fruit. The immediate 51 Rxh6 is a blunder: Crafty fights on with 51...Rd2+ 52 Kc1 Re3 and White's win seems to have evaporated. |
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| Nov-06-10 | | karrs: Someone, please, defuse this thought. 42 Rdc3 BxR 43 RxB Ra1 44 Kc2 a7 45 Kb2 and black loses pawn and white with the advantage. If 42...Ra1 43 Kc2 and we still have the same outcome. |
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| Nov-06-10 | | WhiteRook48: I got it wrong, I said 42 Rd2?!?!?!?! |
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Nov-06-10
| | Phony Benoni: <karrs: Someone, please, defuse this thought. 42 Rdc3 BxR 43 RxB Ra1 44 Kc2 a7 45 Kb2 and black loses pawn and white with the advantage. If 42...Ra1 43 Kc2 and we still have the same outcome.> I think the crucial point arises after <42.Rdc3 Bxc3 43.Rxc3 Ra1+ 44.Kc2>
click for larger view
And instead of pushing 44...a2 at once, Black shifts his rook to f1/g1/h1. That keeps White's king away long enough for ...a2 to work, while White's rook can't get behind the pawn or to the first rank in time. If White tries 44.Kd2, the king is no longer blocking the rook from the first rank and he can counter the rook shift with 45.Rc1. However, his king is now too far away from the a-pawn and 44...a2 works. This position is amazing in how easily White can lose it, even with sensible moves. |
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| Nov-06-10 | | wals: Rybka 4 x 64 : depth 27 : 1 hour 44 min :
1. (3.24): 42.Rdd7 Bb2+ 43.Kd1[] Kg8 44.Ra7[] Ra1+ 45.Kd2 Rf1 46.Ke2 Ra1 47.Rd1 Ra2 48.Rd8+ Kg7 49.Kd3[] Ra1 50.Rdd7[] Rd1+ 51.Kc2 Rc1+ 52.Kd2[] Kf6 53.Rxf7+[] Ke6 54.Rh7 Ke5 55.Rxh6[] Rf1 56.Ke2 Rh1 57.Rg6 2. (3.04): 42.Ra7 Rf2 43.Rd2[] Bb2+ 44.Kc2[] Rxf3 45.b4[] Rc3+ 46.Kb1[] Kg7 47.b5[] Rc1+ 48.Ka2 Ra1+ 49.Kb3[] Rb1 50.Kc4[] Rg1 51.b6[] Rxg4+ 52.Kc5[] Bc1 53.Rd3[] Rg2 54.b7[] Rc2+ 55.Kd5 Rb2 56.Kc6 Rc2+ 57.Kb5[] 3. = (0.00): 42.Rxf7 Ra1+[] 43.Kc2 Ra2+[] 44.Kd1 Ra1+[] 45.Ke2 a2[] 46.Rdd7 Re1+[] 47.Kxe1[] a1Q+[] 48.Kf2 Qb2+ 49.Kg3 Qe5+ 50.Kh3 Kh8 51.Rxg7 Qh2+ 52.Kxh2 Black's blunders
29...Nd4, +1.33. Best, c4, =0.00.
34...Kh7, +2.35. Best, Bf8, +1.89.
36...Re6, +3.07. Best, Bb2, +2.20.
White blunder
42.Rxf7, =0.00. Best, Rdd7, +3.24. |
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| Nov-06-10 | | njchess: Wow... I thought Rdd7 was pretty obvious since Black cannot maintain perpetual check because White's king can escape via d3. White gains a tempo and the win. |
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