|
< Earlier Kibitzing · PAGE 4 OF 4 ·
Later Kibitzing> |
| Nov-01-09 | | Rzep: Nice final position. Black knight can't give up f8 square (because of mate) and black king has no sqare to move.
I believe I've solved Sunday puzzle for the first time. But as I see most of you didn't have serious problems. Maybe the easiest Sunday puzzle ever? |
|
| Nov-01-09 | | chessgolfer: As most did, I saw 50) Rf2 but could not get past the defending and drawish 50..Re7+. Given Black's back rank situation and the fact that the Knight is forever devoted to defending against the passed pawn on f7, Rxb3 seemed suicidal so I didn't give it much thought. Not sure if that's good news or bad news. Interesting to say the least. |
|
Nov-01-09
 | | OBIT: <zanshin and others>: For those lamenting the fact that this position is drawn with best play (uh huh, and who here would find all this OTB), I think we can fix it by moving the Black pawn from d6 to d5. That gives us the following position:
click for larger viewAfter the key move 1. Rf2!, Black has two tries:
1...Rxb3 2. Rg2! Rb1+ (2...Ng6? 3. Rxg6) 3. Kf2 Rb2+ 4. Kg1 Rxg2+ 5. Kxg2 and wins as in the game - bring the king forward, carefully avoiding any knight forks that drop the f-pawn, and pick off the d-pawn and a-pawn. 1...Re7+ 2. Kd2 Re6 3. Rg2! Rg6 4. Rxg6 hxg6 5. Nc5 Kh7 6. Nxa6 Nd7 (or 6...Ne6 7. Nb4 Kxh6 8. Nxd5 Kg7 9. a6) 7. Nc7 Kxh6 8. Nxd5 Kg7 9. a6 and the pawn promotes. It's quite a nice endgame study, IMO. |
|
| Nov-01-09 | | ComboKal: <dannygjk> re: <This is really a study, not a puzzle.> and <once> re: <I think it depends on what you define as a puzzle.>
The Random House Webster's dictionary defines the word puzzle as: <-n 1. a toy, GAME, or problem designed to amuse by presenting difficulties to be solved.> By that definition, I would think that EVERY chess game, along with every position that is presented to be solved, is a puzzle. Maybe the key word here is <"solved">. Sometimes, IMO, solving a chess problem is not finding the win or draw, but just finding a better position. |
|
Nov-01-09
 | | chrisowen: White has tailor made attack and should protect the passed pawn by Rf2. Rook takes knight then Rg2 canvasses it. He again only has checks then white cashes in with a king march since the opposite number is hemmed in the corner. |
|
| Nov-01-09 | | Eisenheim: this was a very easy week |
|
| Nov-01-09 | | zanshin: <It's quite a nice endgame study, IMO.> <OBIT> I played through your first line. Your 2nd with Re7 was immediately not good for Black. Good job with the analysis. |
|
Nov-01-09
 | | Jimfromprovidence: Since we have learned that 50 Rf2 Re7+ draws, how about another move 50 for white instead? I was thinking 50 Rc2!?, below, giving up the f pawn while seeing 51 Rc6. (Note that 50... Rxb3 in the below diagram is not playable because 51 Rc8 is a forced mate.) 
click for larger viewHowever, after my initial enthusiasm, with 50 Rc2 Rxf7 51 Rc6 Rf6 I reached a dead end. 
click for larger view |
|
| Nov-01-09 | | Marmot PFL: This was not that hard to work out. Black is threatening Rxf7 so Rf2 is the only winning try. Rxb3 now Rg2 threatening mate and black has to force the rook trade. Now is there any way to free the black pieces? It seems not and otherwise white just uses his king to take the d and a pawns winning easily. |
|
| Nov-01-09 | | RandomVisitor: Final post: after 50.Rf2 Re7+ :
1: Alexey I Kosikov - Vadim Bezman, Soviet Union 1986
click for larger viewAnalysis by Rybka 3 : <30-ply> <1. = (0.19): 51.Kd2> Re6 52.Rh2 Rf6 53.Rh4 Nd7 54.Ke2 Rxf7 55.Rc4 Kg8 56.Rc6 Rf6 57.Rxa6 Rxh6 58.Nd4 <2. = (0.19): 51.Kd1> Re6 52.Rg2 Rg6 53.Rh2 Rf6 54.Rh4 Nd7 55.Rg4 Rf1+ 56.Ke2 Rxf7 57.Rc4 Kg8 58.Rc6 Rf6 59.Rxa6 Rxh6 60.Nd4 <3. = (0.18): 51.Re2> Rxf7 52.Re8 Kg8 53.Ra8 Rf6 54.Rxa6 Rxh6 55.Rb6 Ne6 56.Rxd6 Kf7 57.Rd7+ Ke8 58.Rb7 Nd8 59.Rb5 Kd7 60.Kf2 Kc7 61.Kg3 Nb7 62.Re5 Nd6 63.Kg4 Rg6+ 64.Kf3 Rh6 65.Re7+ Kc6 66.Nd4+ 4. = (0.05): 51.Kf1 Re6 52.Rc2 Rxh6 53.Rc6 Kg7 54.Rxa6 Kxf7 55.Rc6 Ne6 56.Rxd6 Rh2 57.Rd7+ Ke8 58.Rd5 Ra2 59.Ke1 Nf4 60.Rd4 Ne6 61.Rh4 Ra3 62.Rh6 Nd8 63.Nd4 Rxa5 64.Ke2 Nf7 |
|
| Nov-01-09 | | agb2002: Material is even. Black threatens 50... Rxf7. If both rooks and the white knight disappeared White would win by capturing Black's d pawn and then the a pawn because the black knight could only cycle between f8 and d7 or g6. The only detail to take into account is to place the king on c8 just before crowning in case the black knight is on f8 to avoid the stalemate. This suggests 50.Rf2, threatening Nd4 - Ne6 Nxe6 - f8=Q+ Nxf8 - Rxf8#: A) 50... Rxb3 51.Rg2 (threatens 52.Rg8#) Rb1+ (51... Ng6 52.Rxg6 Rb8 53.Re6 + -) 52.Kf2 Rb2+ 53.Kf3 Rxg2 54.Kxg2 + -. B) 50... Re7+ 51.Kd2
B.1) 51... Re5 52.Rg2 Ng6 53.Rxg6 + -.
B.2) 51... Rc7 52.Nd4 Re7 53.Kd3 Rc7 54.Ne6 Rc8 55.Nxf8 Rxf8 56.Kd4 + -, the White king will capture Black's queenside pawns. C) 50... Rc7 51.Nd4
C.1) 51... Re7+ 52.Kd2 transposes to B.2.
C.2) 51... Rc8 52.Kd2 and the king will invade Black's position because the rook cannot leave the back rank and the knight cannot move from f8 because of Ne6. I don't have the time today for a deeper analysis but I have the impression that this is the essential of the position. |
|
| Nov-01-09 | | MaczynskiPratten: Many of the positions this week have brought a smile to my face. Many have been counter-intuitive. The idea of White deliberately letting his only two pieces be taken or exchanged and going into an ending a piece down - amazing! And the final zugzwang position - who would have thought that a knight and pawn could be so helpless against a lone king? As pointed out previously, the heroes are White's f7 and h6 pawns which tie up Black's king single-handed. It looks like a composed study, but it's real! |
|
| Nov-01-09 | | wals: Ah I see now why 50.Rf2..
Alexey I Kosikov - Vadim Bezman, Soviet Union 1986
Analysis by Rybka 3 1-cpu: Ply 24 time 16 min 18 sec 1.  (0.72): 50.Rc2 Rxf7 51.Rc6 Ra7 52.Kf2 Kg8 53.Rxd6 Nd7 54.Ke3 Kf7 55.Kf4 Ke7 56.Rc6 Rb7 2.  (0.40): 50.Re2 Rxf7 51.Re8 Kg8 52.Ra8 Rf3 53.Nd4 Rf4[] 54.Nc6 Kf7[] 55.Rxa6 Nd7 56.Ra7 Ke6 57.Rb7 Rc4[] 58.Nd8+ Ke7[] 59.Nf7 Ra4[] 60.Ra7 Kxf7[] 61.Rxd7+ Ke6 62.Ra7 Ra2[] 63.Kd1 Kf6[] 64.Kc1 Kg6 65.Kb1 |
|
| Nov-01-09 | | wals: 50....Rxb3 was a blunder |
|
| Nov-01-09 | | David2009: Sunday's insane puzzle A Kosikov vs V Bezman, 1986 White 50? It is 9 PM local time and I have just started this puzzle, I need to wrap it up quickly if at all.
My first thought is 50 Rf2!? Rxb3 and the intended Rg2?? loses to Rb8+ exchanging Rooks and winning.
Back to the drawing-board: 50 Rf2!? Rxb3 51 Kf1!? Rb1+ 52 Kg2 Rb7 and Black is more mobile than White, so this fails as a
winning attempt. WAIT! 51 Rf6 and Black's King side is tied up. Moreover White can play Rxd6 with impunity unless Black is threatening the f7 Pawn This must be it. 50 Rf2 Rxb3 51 Rf6 and the ball is in Black's court. Time to
check:
=====
I missed the game continuation - White can afford to exchange Rooks!! Truly bizarre; truly elegant; truly INSANE! Crafty check: http://www.chessvideos.tv/endgame-t...
My line 51 Rf6 LOSES: 51...Rd3 (threatening Rd5 and taking the a pawn) 52 Rf5 Rg3 53 Rf6 (hoping for repetition) Rg6! 0-1
"The blunders are all there, waiting to be made" - Tartakower. 
click for larger view Kosikov-Bezman 50? Crafty loses to the game line 50 Rf2 Rxb3 51 Rg2 Rb1+ 52 Kf2 Rb2+ 53 Kg1 Rxg2+ 54 Kxg2, varying at move 54: 54...d5 55 Kf3 d4 56 Ke4 e3 57 Kxe3 Ne6 58 Kc4
Nf8 59 Kd5 Ne6 60 Kd6 Nf8 61 Kc7 Nd7 62 Kb7 Nc5+ 63 Kxa6 and wins. White only has to avoid variations losing the f7 or h6 Pawn to a N fork. |
|
| Nov-01-09 | | remolino: This problem is insane indeed because as Rybka points out (thanks to wals) the right answer is 50.Rc2. Then Black, after taking on f7, must defend the a pawn, yet white keeps a more active position. This is the solution - best play for both sides - no one got the answer today! Like many of you, I got the line with 50.Rf7 sacrifizing knight and exchanging rooks, reaching a won king vs knight ending. Others went further than me and recognized that 50...Re7+ drew for Black. But none gave 50.Rc2 as the winning line with good variations to support that answer. Amazing. Insane. Wonder what Kasparov or Topalov would have done OTB. |
|
| Nov-01-09 | | WhiteRook48: I tried 50 Rg2 |
|
| Nov-01-09 | | Criswell: Ok..I look at this position and the immediate 50. Rg2! shouts to me saying "Hey look I threaten mate!" so 50. Rg2 it is! -------------------
50. Rf2. Interesting move but I fail to see why it is superior to Rg2. Anyone care to point me in the right direction? |
|
| Nov-01-09 | | dannygjk: My computer prefers 50.Rc2 but seems to lead to a draw. As with most of the humans I liked 50.Rf2 but 50...Re7+ seems to equalize. |
|
Nov-01-09
| | OBIT: <remolino>50. Rf2 is correct because very few human chessplayers would never see that the only drawing line is that Re7+ followed by Re6 thing. Your stupid computer has a lot to learn about human behavior. |
|
| Nov-01-09 | | CHESSTTCAMPS: Material is even in this endgame, but it seems that white faces a terrible choice of giving up a critical pawn on f7 or the pinned knight on b3. My first thought on looking at this was that maybe white could could play 50.Rf2 Rxb3 51.Rg2 to threaten mate. Oh no, black has Rb1+ followed by Rb2+ and all is lost. Too bad white's rook and knight aren't one square up the board, then the king could approach the black rook and end the checks... Then, suddenly it occured to me that it
doesn't matter - white's f7 and h6 pawns are superpawns, worth far more than a knight! 50.Rf2! (after all) at least draws and seems to win against anything but the most accurate defense. A) 50... Rxb3 51.Rg2! Rb1+ 52.Kf2 Rb2+ 53.Kf3 Rxg2 54.Kxg2 reaches a position where black's king is in a coffin and black's knight is under house arrest - any move to a square other than d7, e6, and g6 allows a winning promotion. So white should win it by strolling the king down the board to pick up the d-pawn and then the a-pawn. White just needs to
avoid stalemate and be careful that the approach does not step into a fork that picks off the vital f7-pawn. Success is ensured because white's king can triangulate, while the opposing knight can't. Therefore play might continue: 54... Ne6 55.Kf2 (Kf3?? Ng5+ - taking the shortest path by routine leads to disaster!) Nf8 56.Ke3 Ne6 57.Kd3 d5 58.Ke3 Nf8 (d4 59.Kc4) 59.Kd4 Ne6+ 60.Kxd5 Nf8 61.Kc6 Nd7 62.Kb7 (Kxd7?? is stalemate) Nc5+ 63.Kb6 Nd7+ 64.Kxa6 Nc5+ 65.Kb5 Ne6 (Nxa6 f8=Q#) 66.a6 Nc2+ 67.Kb6 Ne6 68.a7 Nf8 69.Kb7 (a8=Q?? stalemate) Ne6 70.a8=Q+ Nf8 71.Qxf8# A.1) 51... Ng6 52.Rxg6 Rb8 (hxg6? 53.f8=Q+ Kh7 54.Qg7#) 53.Re6! (Rxd6?? enables a stalemate enforced perpetual check) Rf8
54.Re8 forces mate.
A.1.1) 53.Rxd6?? Rb1+ 54.Ke2 (Rd1 Rxd1+ 55.Kxd1 stalemate) Rb2+ 55.Ke3 Rb3+ 56.Ke4 Rb4+ 57.Ke5 Rb5+ 58.Ke6 Re5+! 56.Kd7 (Kf6 Re6+ 58.Kf5! Re5+! etc) Re7+ 57.Kc6 Rc7+ 58.Kb6 Rc6+ 59.Kb5 Rc5+ (Rxd6?? 60.c8=Q#) and black can check forever on the c-file.
A.2) 53... Rb3+ 54.Ke4 d5+ 55.Kxd5 Rb5+ 56.Kc4 Rb4+ 57.Kxb4 Ng6 58.Rxg6 hxg6 59.f8=Q+ Kh7 60.Qg7# B) 50... N moves 51.f8=Q+ NxQ 52.Rxf8#
C) 50... Rb4/Rb5 51.Rg2 forces mate as in A.1. The f7-pawn effectively ties the black rook to the 7th/8th rank, just as king and knight are tied. In other lines, white adds the knight to the attack and avoids stalemate traps: D) 50... Rb8 51.Nd4 d5 52.Ke2 Rb2+ 53.Ke3 Rb8 (Rxf2 54.Kxf2 is winning as in A even without the knight) 54.Rf6! (preparing Ne6) Nd7 55.Re6 Nf8 56.Re8 Rb3+ 57.Nxb3 d4+ 58.Kd2! d3 59.Rxf8# D.1) 51... Rc8 (a8/d8) 53.Rf6 immediately
D.2) 51... Nd7 (g6) 52.Ne6 Nf8 53.Nxf8 Rxf8 54.Kd2 with a winning zugswang. D.2.1) 52...Rb1+ 53.Ke2 Rb2+ 54.Ke3 Rb4+ 55.Kc3 Rb8 56.f8=Q+ Nxf8 57.Rxf8+ Rxf8 58.Nxf8 Kg8 59.Nd7 Kf7 60.Nb8 Kg6 61.Nxa6 wins easily.
E) 50... Re7+!
This is the most active defense, that requires exceedingly accurate play from both sides. The plan is to use the tempo to go after the pawns that keep black tied down. So far as I can see, the best play seems to be: 51.Kd2 Re6 (otherwise 52.Rf6 keeps black locked down) 52.Rg3 Rg6 (Ng6? 53.Rxg6 wins) 53.Rxg6 (regrettable because it releases the king from the vice, but otherwise white loses a key pawn immediately) hxg6 54.Nd4 Kh7 55.Nb5! (the knight can't be taken) Kxh6 (55...d5?? loses to 56.Nc7 Kxh6 57.Nxa6 Kg7 58.Nc5 locks out the defending knight and the a-pawn scores) 56.Nxd6 Kg7 57.Ne8+ Kxf7 58.Nc7 Ke7 59.Nxa6 Kd7 With each defending king within the square of the opposing passed pawn, I must conclude that this is drawn. F) 50... d5 51.Nd4 Rb1+ 52.Ke2 Rb2+ 53.Ke3 transposes to D. This is a fascinating puzzle, even if I've missed a win against black's best defense. Time to peak. |
|
| Nov-01-09 | | Formula7: I think after 50.Rf2 Rxb3 51.Rg2 Black can't play 51...Ng6 because of 52.Rxg6! So after 51...Rb1+ 52.Ke2 Rb2+ 53.Kf3 Rxg2 54.Kxg2 Black's king has no moves and his knight cannot leap more than 1 leap from f8. From here White can take Black's d-pawn and his a-pawn and promote his own a-pawn, winning easily. On the other hand, 50...Re7+ seems to draw, e.g. 51.Kd2 Re6 or 51.Kf1 Re6. |
|
| Nov-01-09 | | remolino: OBIT:
In a puzzle we not only look for the best practical chance OBT, we also look for the actual best move. We also look at this as a chess problem, in a pure scientific sense. |
|
Nov-02-09
| | OBIT: <remolino>I suppose one problem with posting on the Internet is that there is sarcasm font. Someone needs to invent one. Seriously, though, the "truth" in any chess position really just boils down to three possibilities: either you can win, you can draw, or you have lost. In the puzzle position, since it seems clear White has no move that wins against best defense, Rybka's numerical evaluations for 50. Rc2 vs 50. Rf2 seem kind of pointless to me. The "truth" is that both moves draw. If you have to pick a "best move" in a situation like this, I think you have to go with the move that requires the most accurate defense, although that just opens up another can of worms - how do you measure "most accurate defense"? People like to think chess is an exact science, but I don't think this is true at all. There is lots of fuzzy logic in this game. |
|
| Nov-02-09 | | RandomVisitor: After 50.Rc2 Rxf7 51.Rc6 Rf6 52.Rxa6 Rxh6 53.Rc6 Rh4: 1: Alexey I Kosikov - Vadim Bezman, Soviet Union 1986
click for larger viewAnalysis by Rybka 3 : <27-ply> 1. (0.32): 54.Rxd6 Ra4 55.Kd2 h5 56.Rh6+ Kg7 57.Rxh5 Ne6 58.Kc3 Kf8 59.Rb5 Ke7 60.Re5 2. (0.32): 54.Kd2 Ra4 55.Rxd6 h5 56.Rh6+ Kg7 57.Rxh5 Ne6 58.Kc3 Kf8 59.Rb5 Ke7 60.Re5 |
|
 |
|
|
< Earlier Kibitzing · PAGE 4 OF 4 ·
Later Kibitzing> |
Kibitzing
sac: 50.Rf2