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Later Kibitzing> |
| Feb-27-11 | | gofer: Well, I can see a very nice combination that black has to avoid, so black cannot
accept the sacrifice, so we probably follow this line, which looks to be winning
for white...
<25 Rxd4 bxc4>
<26 Rd5 Qxa2?>
<27 Nxe5 Nxe5> (... Nb6/Nf6 28 Nc6+ seems to be good for white)
<28 Bxe5 Bxe5>
<29 Rxe5+ Kd6>
<30 Rd5+ Kc6>
<31 Rd4 winning>
But lets look at the acceptance, which is much more interesting! <25 Rxd4 exd4>
<26 Bd6+ ... >
Black has two choices Ke8 and Kf6. Kf6 loses quite quickly! 26 ... Kf6
27 b4 Qa6 (Qa3 28 Rc6! and 29 Bf8# next)
28 Rc6 Qxc6
29 Bxc6 Kxf7
30 Bxd7 winning
<26 ... Ke8 >
<27 Bd4! ...>
click for larger viewWhite is threatening Rc8#. Bf6 moves and Qd8 moves lose the queen, so Nb8/Nb6/Nf8/Nf6 are the only ones available! 27 ... Nf6 28 Nd5! winning
27 ... Nb8 28 Be6! winning
27 ... Nf8 28 Rc7 Bf6 29 Bd5! winning
<27 ... Nb6>
<28 b4 ...>
I have looked at the variations after this and cannot find a way forward for white... ...pity! Time to check what I
have missed! |
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| Feb-27-11 | | kutuzov: Got the jist of this one.
I saw Rxd4, the bishop check afterwards, that Kf6 was swiftly met with e5+, and that capturing the bishop led to Rd5 followed by doubling the rooks. Didn't even bother to look at Ke8. It seemed like a losing move, but there is a little more nuance than I thought. 28. b4 is the key to the whole combination, preventing the back rank mate and allowing the rook complete the mating net on c7. Even though I dismissed the main line a little bit, I'll still give myself a pat on the back. :) |
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| Feb-27-11 | | alachabre: <kutuzov>, I have to disagree, I think 28. b4 is irrelevant, although it did induce Black to blunder Qa3. There is no back rank mate, h2 is open. |
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| Feb-27-11 | | Rama: Scormus, refer to Averbakh's "Advanced Chess Tactics" where he elucidates the Theory of Contacts. Each contact is a potential capture. As the number of contacts grows so does the potential for a combination. I learned a lot from that book. |
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| Feb-27-11 | | alachabre: <scormus>, re your comment about never playing an exchange sacrifice OTB, reconsider! If the position calls for it, it is one of the strongest tactics available to the player. Now, I may have a bias for liking it; you see, my only victory over a master in a rated game featured an exchange sac very much like the one in this game. I seek them out now, if it's even just a little bit sound, it can have great shock value. |
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| Feb-27-11 | | checkmateyourmove: great puzzle, worthy of a sunday! |
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Feb-27-11
 | | scormus: <alachabre and Rama> thanks, and youre right about the tactical strengh of such a sac. I suppose what I mean is ... its one thing to find it in a puzzle and post it on the forum, another to play it in a match when your team needs you to not lose. I admit, there've been games I didnt win because I chickened out of playing the important sac. I suppose whats really important is knowing to play a winning sac even if you cannot see the sequence right through. A very strong club mate once pointed this out after a game, saying "I might not be able to see the whole sequence but I know it wins. How? These positions always do." I hope I these puzzles are helping me to learn this. |
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| Feb-27-11 | | JKnight94: @ alachabre "I have to disagree, I think 28. b4 is irrelevant, although it did induce Black to blunder Qa3. There is no back rank mate, h2 is open." In fact b4 is necessary. If white plays 28. Rc7 immediately black follows up by 28...Qe1+ 29. Kh2 and Bf8! Note that white can't play Ng5 now because Bxd6+ is check. When white played 28. b4 he actually stopped the queen from being able to enter the first rank, stopping the king from coming to h2 and therefore having the option to play Ng5 later which is crushing. So it was relevant after all wasn't it? |
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| Feb-27-11 | | theodor: I checked out for 25. ..;bxB , but didnt found any! |
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| Feb-27-11 | | AGOJ: Well, I have to say I missed it because after 25.Rd4 bxc4 I couldn't see a clearcut continuation for White. Taking the rook with 25...exd4 seemed to me a mistake, and inferior to 25...bxc4. Perhaps someone with access to computer analysis can enlighten me. |
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| Feb-27-11 | | alachabre: <JKnight94>, I appreciate the analysis, but I still disagree. I see that b4 does help deflect the queen from the first rank, but only if Qa3 is played. If Qa4, there is no real difference from an immediate 28. Rc7 - the Black queen can still safely gain the first rank. After your 29. ... Bf8, 30. Bxf8 is solidly winning for White. |
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| Feb-27-11 | | Combopack: Can someone explain the 23. Nd7 move by black. Why not Kxd8? |
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| Feb-27-11 | | stst: late in the game...
25. Rxd4 exd4
26. Bd6+ Kf6
(the other option is Ke8, also won by W.)
27. b4 Qa6 / Qa3 (doesn't matter much.)
28. Bd5 d3
29. e5+ Nxe5
30. f4 d2
31. fxe5+ Kf5
32. Rf1#
somewhat messy (quite a lot of sub-variations,) not too insane!!
Now is bed time!! |
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Feb-27-11
 | | Phony Benoni: <Combopack: Can someone explain the 23. Nd7 move by black. Why not Kxd8?> 
click for larger viewLooks like our old friend <24.b4> comes into play here. If Black tries to defend the e-pawn with 24...Qxc7, then 25.Rxd4+ since the e-pawn is pinned. On other queen moves, White plays 25.Bxe5, regaining the piece with all his forces centralized and aiming at the Black king. I suspect Black knew by now that this wasn't going to be all fun and games. |
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| Feb-27-11 | | sevenseaman: < Combopack: Can someone explain the 23. Nd7 move by black. Why not Kxd8?> 23... Kxd8 24. b4 Qxb4 25. Bxe5 only serves to make White's job easier. |
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| Feb-27-11 | | sevenseaman: Mine and <Phony Benoni>'s response to <Combopack>'s query have obviously overlapped in time. |
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| Feb-27-11 | | avidfan: 
click for larger view
In the final position Black is mated even after 31...Bxd6 because 32.Ne6# protects the rook at c7. The Black queen cannot check at c1 (to fork the N/g5) since c1 is controlled by White R/c7. |
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| Feb-27-11 | | sevenseaman: Hi< morfishine>. Good to see you diverting from your more serious pursuit and getting involved in the daily puzzle. Welcome. Like you I too used to feel very irritatingly distracted by an avalanche of solver's comments without any heed to the overall game quality. I decided to join in (as it was an evil I could not wish away). Now I know why its aficionados are so addicted - a helplessly and terminally afflicted lot! Its a powerful tool floated by cg and we are all hooked. The days I cannot solve, it breaks my heart. But then that is how a challenge is supposed to dare you, taunt you and goad you. Lets hope we are improving some of our intrinsic game skills. P.S.
I follow you and <Once> closely, and not only because the two of you have easily accessible shiny blue avatars that are visible from miles. |
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| Feb-28-11 | | TheoNov: <Combopack: Can someone explain the 23. Nd7 move by black. Why not Kxd8?> An excellent question! And with all due respect, I feel the answer is not quite as straightforward as PhonyBenoni/sevenseaman claim. The best answer I can give is that White gets a winning endgame, but definitely no crushing win. For instance: 23. .. Kxd8 24. b4 Qc7 25. Rxd4+ Ke7 26. Rcd1 Bh6 27. Bb3 b5 28. g4 Bc1 29. Kg2 h6 30. Rd6 Nxe4 31. Rd7+ Qxd7 32. Rxd7+ Kxd7 33. Bxf7 Kd6 34. Bxg6 Nc3 35. Bf7 Nd5 36. Kf3 Nf4 37. h4 Ba3 38. Bxf4 exf4 39. Kxf4 Bxb4 40. g5 Ke7 41. Bd5 Bc5 42. f3 a5 43. h5 Kd6 44. Bb3 a4 45. Bc2 Ke7 46. gxh6 Kf8 47. Ke5 Kf7 48. f4 Bb6 49. h7 Kg7 50. f5 Kxh7 51. f6+ Kg8 52. h6 Bc5 53. Ke6 b4 54. f7+ Kf8 55. Bxa4 Bd4 56. Bc6 Bh8 57. Be4 Bd4 58. h7 Bh8 59. Bg6 Bg7 60. Kd5 Bc3 61. Kc4
and finally White will promote.
BTW, I don't think anyone has pointed out that 23...Nd7? is a serious mistake, because it effectively loses immediately by allowing White's tactical blow 24.Nxf7!!
Correct for Black is 23...Ne8 with complete equality. |
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| Feb-28-11 | | sevenseaman: < TuxedoKnight> Thanks for a very good collection of chess puzzles. |
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| Feb-28-11 | | tacticalmonster: 1) White has two rooks and a pawn verus a queen
2) LSB is under attack and it has the bothersome task of defending f7 N, e2 square and the a2 pawn 3) h2 bishop creates backrank weakness and it is also hammered in by the e5 pawn 4) Black has a monstrous d4 knight. It blocks the d-file and threatens Ne2+ winning the exchange 5) Black king lacks pawn shelter and only the two blacks N are holding BK's position candidate: 24 Rxd4
a) 24...exd4 25 Bd6+ Ke8 26 Be6 Nb6 27 Rc7 Qe1+ 28 Kh2 Qxf2 29 Re7+ Kf8 30 Rd7+ Kg8 31 Nh6++ Kh8 32 Rd8+  White would be up lots of materials b) 24...bxc4 25 Rd5 Qxa2 26 Nxe5 Nb6 27 Rb5 White maintains his material plus |
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Feb-28-11
| | scormus: <alachabre: <JKnight94>, I appreciate the analysis....> I too appreciate the discussion on this point. It seems to me the most tricky question of the sequence and was the one that bothered me most at the time, to b4 or not to b4? Yes, it certainly induced ... Qa3? But with the BQ still on a5, it would be ... Qe1+ instead of Qd1+. Either way after ... Bf8 W cannot play Ng5. I dont see much difference between the two outcomes - both clear advantage for W, though not winning as immediately as in the game. From Grigore's OTB position, the chance to decoy the BQ was worth taking. |
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| Feb-28-11 | | TheoNov: scormus, alachabre and JKnight94:
The difference is that after 28.b4 it's maybe easier to calculate, but the result is the same. White ends up a piece up in both cases. Here is the analysis [Houdini]:
With b4, as in the game, but Black plays the superior 29...Bf6: 28. .. Qa3 29. Rc7 Bf6 30. Rb7 Qc1+ 31. Kh2 Nc8 32. Rb8 d3 33. Rxc8+ Qxc8 34. Bxc8 d2 35. Bg4 Kxf7
click for larger viewWithout b4: 28. Rc7 Qe1+ 29. Kh2 Bf8 30. Bxf8 Kxf8 31. Nd6 Qxf2 32. Rf7+ Qxf7 33. Bxf7 d3 34. Kg3 Ke7 35. e5 d2 36. Bb3 
click for larger view |
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| Mar-05-11 | | morfishine: <sevenseaman> Good to hear from you. Sorry for the belated response. Frankly, I don't 'search kbitz' my own name very often and rarely return to a puzzle, so sorry I missed your comments. I find the puzzles very useful to improve one's "tactical eye". I feel like I'm getting better at these. How have you been doing at them? One of the tricks is to first realize if one side is trying to win or draw. One could go mad trying to force a win when in fact the solution is to hold the draw! Keep at it! Feel free to drop by my forum. I've been spending a lot of time an an endgame variation of the POGO game. Here is one variation:
morfishine chessforum
I'm almost done with one more variation to look at.
Happy Chess! :) Morf |
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| Aug-20-12 | | DrChopper: Why not 23.Kxd8 24.b4 Qb6 25.Bxe5 Nh5 26.Rxd4 Ke8 27.Bxg7 Nxg7 28.Rcd1 Ne6 29.Bxe6 fxe6 going into an end-game rooks vs queen. |
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Later Kibitzing> |
Kibitzing
sac: 25.Rxd4