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| Apr-07-13 | | sfm: <Alphastar: The puzzle is difficult because it involves a few quiet moves that seemingly do very little.> Right!
Larsen was once asked about how far he could see ahead in chess games (a common question from people with home-player level). Larsen said:
"Precise calculations over ten moves are very rare [I agree! :-)]. In some endgames you can get much higher. But what is really difficult is to find the quiet winning move in the middle of a series of checks, captures and threats." 28.Qb6 is one of those moves. Really hard to see from just 3 moves back. |
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Apr-07-13
 | | chrisowen: Thought <25.g5> rinc ha do it now in adage hinges, at goofy 25.g5 light in ascendancy since good call it book in light find longer bill to rights inbeaky, 25...Qh2 or he feeds 25...rh5 chef one curious again to see how black wriggles it I would perform rook entrap merciful in heave 25...Qh2 eek needed, groan I think e5 prodding around forces 26.Qc5+ even time to get back to grind 25.rh5 allow, grounds i cross hex dagger you in flight 26.qd6+ aimed dervish in stone king on back footing good to gauged 26...Kg7 look it double give up ridings 27.g6 oy oys ai l0 re boys and girls rib a finding. |
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Apr-07-13
| | chrisowen: Rook in formation will take off f7 leading gauge,
back you in mass piece swop down to gradings 28.Qd4+ black interjected pace e5 described, 29.Rxf7+ and following ooses contempt for home straigt all white need several trades of f7 light, of fancy his chances take in e5+ king up ply it old a 31...kxf7 in or con a 31...Kg6 looks to wrap it up you in g5 feels right ixion king has to prevent f8 in eight ball free fall liner cuffing good g5, white in emerges rook for bishop plus aint two pawns kingside into win er endgame by a comfortable margin so sheaf 25.rh5 can be discarded eli g1 ht it dog in digger light woofer tile ground in g5 g6, all cases nearly in light really it hop in recce 25.g5 Qh2 26.Qc5+ a king chux bridge suits you in chins 26...Kg8 ar go et he im at be 27.g6 oh door it booking 27.f6 low at er flooding 28.Qb6 in, good to reverse the trend forge stapled g/e line wobble sage in counting for dilemma in exactly it honour in side by side f6 i e6 finding a gap in favouring 29.g7! crossed in e8 to protected e6 berth, wider in lambasted 29...Qxg1+ over now in chap ply see at enact in just again head jog 30.Qxg1 black double pawnine line beating down a path to er include rigor in betcha a a3 etc b2 and c2 vite again very it is a g7 ie chaingang dip man tis king, deliver advantage off came light into the mixing evasive maneovre it her bidbin b6 in feed the pigeons a guessing 28...bc4 29.g7 30.Qxg1 he in ploughing crest retract or in dilligent zest I make, wind in g7. |
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Apr-07-13
 | | Jimfromprovidence: Here is the puzzle position.
click for larger viewI liked 25 g5 as well, because of the threat 26 g6, seeing 27 Rxf7+ I also noticed that black couldn’t counterattack with 25...Qg2??, because of the mate in one threat Qxh8# <goodevans White can now win back his piece, e.g. 25...Rh5 26.Qd6+ Kg7 27.Qd4+ e5!> I would try 27 g6 instead, with the threat 28 gxf7+
click for larger view |
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| Apr-07-13 | | goodevans: <Jimfromprovidence: ... <goodevans White can now win back his piece, e.g. 25...Rh5 26.Qd6+ Kg7 27.Qd4+ e5!> I would try 27 g6 instead, with the threat 28 gxf7+> That certainly looks very menacing, but would <27...Rg5> hold? After <28.Rxf7+ Kg8> black's K looks very precarious but I can't see a way through for white. <29.Rg7+> is interesting but I think it does no better than draw by repetition. |
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Apr-07-13
| | Jimfromprovidence: <<goodevans> That certainly looks very menacing, but would <27...Rg5> hold? After <28.Rxf7+ Kg8> black's K looks very precarious but I can't see a way through for white. <29.Rg7+> is interesting but I think it does no better than draw by repetition.> Try 29 Qxe6!?
click for larger viewWhite's would answer 29...Rxg1+ with 30 Rf1+, below, with the intent to check with the queen on f7, forcing the king to the h file. 
click for larger view |
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| Apr-07-13 | | snakebyt: I did this:
25. Pg5 Qh2 26. Qc5+ Kg8 27. Pg6 Kg7 28. Pxf6 Kh7 29. P=Q#It took me an hour. |
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| Apr-07-13 | | Patriot: <sfm> Great points! This position really perplexed me because of the pretty significant material difference (white has just a pawn for a piece!) and nothing seemed forcing enough to compensate. I evaluated 25.Qf4 Qh7 as very good for black because usually anytime the player with more material can defend in a solid way, it will favor them. Houdini said it is even! After reviewing this, I really wondered what I could have done differently. The one thing that stands out is "look for a move that fights back and stick with it". 25.g5 stood out with me early on but after 25...Qh2, I didn't see the point behind 26.Qc5+. I don't think I really noticed it also protects the g1-rook. But perhaps more importantly, recognizing that 25.g5 is probably white's only shot at getting back in the game is enough to focus on that move (or simply play it OTB as a practical decision). |
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| Apr-07-13 | | goodevans: <Patriot: ... recognizing that 25.g5 is probably white's only shot at getting back in the game...> Of course, white was probably planning on playing 25.g5 back when she sac'd her N several moves earlier since the subsequent moves were pretty much forced. |
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| Apr-07-13 | | goodevans: <Jimfromprovidence> Yes, that looks fairly convincing. |
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Apr-07-13
 | | AylerKupp: <<morfishine> After 25.g5 Rh5 I'd like to see how an engine defends against <26.Qc7>> According to Critter 1.6a Black stands fairly well after 25.g5 Rh5 26.Qc7.
click for larger viewAt d=26 it evaluated the position at [-0.44]: 26...Qf2 27.Rgd1 Rc8 28.Rd8+ Kg7 (28...Rxd8 fails after 29.Rxd8+ Kg7 29.Qe5+ f6 30.Qxf6 31.Rg8+ Kxg8 32.Qxf6) 29.Rxc8 Bxc8 30.Qc3+ (this is a mistake, giving Black a tempo for ...e5, but I am not sure if it is significant) 30...e5 31.Qxc8 (if 31.Qxe5+ the bishop escapes and Black remains a piece up) 31...Rxg5 32.b4 Rg1 33.Rxg1+ Qxg1+ 34.Kb2 e3 35.Qc3 f6 36.Qc7+ Kg6 37.Qd8 Qf2 38.Qg8+ Kf5 39.Qh7+ Kf4 40.Qh6+ Kg3 41.Qg6+ Kh4 (Black has better moves, reaching the same position quicker, see below) 42.Qh6+ Kg4 43.Qg6+ Kh3 44.Qh5+ Kg3 45.Qg6+
click for larger viewCritter apparently has difficulty realizing that on move 41 Black should continue forward and go around its queen and use it as a shield. Then, after White runs out of checks, Black should win the queening race. This is what Critter came up with staring from the position after 41.Qg6+ (the same position as after 45.Qg6+ above), showing once again the need for sliding forward. At d=25 Critter evaluates the position at [-3.53] after either of 3 moves, 41...Kh4, 41...Kh3, and 41...Kh2. Here is the line starting with 41...Kh2 since I think it is the most direct even though the queening race ends up in a tie (but with Black to move): 41 ...Kh2 42.Qh5+ Kg1 43.Qg4+ Qg2 44.Qh4 (if 44.Qd1+ then 44...Kf2 and White is out of checks) 44...e2 45.b5 Qf2 46.Qxf2+ (if 46.Qg4+ then 46...Kf1 47.Qh3+ Ke1 48.a4 Kd2 and Black's front e-pawn queens after either 49.Qh5+ Qe3 or 49.Qd7+ Qd4+) 46...Kxf2 47.b6 f5 (after 47...e1Q Black can't stop White's b-pawn from queening! So Critter decides to get Black's f-pawn moving so that Black is once again ahead in the next queening race) 48.b7 e1Q 49.b8Q f4 50.Qh8 f3 51.Qh2+ Kf1 52.Qh3+ (at this point I get a feeling of déjà vu all over again!) 52...Ke2 53.Qh7 Qa5 54.Qe4+ Kf2 55.Qh4+ Ke3 56.Qh6+ Ke2 57.Qc6 Kf2 58.Kb3 Ke3 59.Qh6+ Ke2 60.Qh5 (White has run out of constructive checks) 61...Qb6+ 61.Kc4 e4 62.a4 Qb1 63.a5 Qxc2+ 64.Kb4 Qd3 65.Qg4 e3 66.Qh5 Qe4+ 67.Kc5 Qa4 68.Kb6 Qb4+ 69.Kc6
click for larger viewBlack should be able to win this given his advanced passed pawns. And Critter agrees, indicating a mate in 29 starting from this position at d=20 after 69...Qe4+ and mate in 32 after 69...Kf2. I suspect that Critter would find shorter mates if I let it run longer but that is not important. All the moves since 26...Qf2 seem semi-forced and I can't find any improvements for White other than the immediate 30.Qxc8. Black has the advantage due to his more advanced passed pawns. White must keep checking to try to avoid the inevitable, and the most that it can hope for is a draw by repetition. So I would say that after 25.Rg5 Rh5 26.Qc7 Qf2 it's a forced win for Black. |
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Apr-07-13
 | | agb2002: White has a pawn for a bishop.
Black is probably considering ... Rc8, ... Bd3, ... Qh2, etc. White can incorporate another piece into attack with 25.g5: A) 25... Qh2 26.Qc5+
A.1) 26... Ke8 27.Qe7#.
A.2) 26... Kg7 27.g6 Ra(h)f8 28.Qd4+ Kh6 29.gxf7 looks bad for Black. A.3) 26... Kg8 27.g6 f6 28.g7 Rh7 29.Qb6 Bc5 30.Rd8+ wins. B) 25... Rg8 26.Qf6 Qh7 (26... Rg7 27.Rd8+ Rxd8 28.Qxd8#) 27.Qe7+ Kg7 28.Qxf7+ Kh8 29.Qxh7#. C) 25... Rh7 26.Qd6+ followed by g6 looks winning.
That's all I can do today. |
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Apr-07-13
| | agb2002: <AylerKupp: <<morfishine> After 25.g5 Rh5 I'd like to see how an engine defends against <26.Qc7>>> I can do a bit more: I'd prefer 26.Qf6, instead of 26.Qc7, 26... Rh7 27.Qe7+ Kg8 26.g6 winning (26... Qxe7 27.gxh7+; 26... fxg6 27.Qxe6+ Kf8 (27... Kh8 28.Qe5+ Kg8 29.Qd5+) 28.Qd6+ Re7 (28... Ke8 29.Rxh7 Qxh7 30.Qc6+) 29.Rxe7 Qxe7 30.Qxg6 Qf7 31.Qd6+ Ke8 32.Qc6+). |
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Apr-07-13
 | | PawnSac: < vinidivici: <Skakalec: <vinidivici> I don't now how you react in your variation after 27...Bxf1 ?> oops, that is really my bad. its a mistake.
<The first line i thought> Just like i said, that is the first line i thought but apparently i missed something. I rechecked that line after 25...Rg8, it should be 26.Qf6....and the attack is too strong now. I was too in rush the first time.... >
After 25.g5 ..Rg8 is now out of the question since
26.Qd6+ Kg7 27.Qxe6! Rgf8 28.g6! with a deadly attack. |
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Apr-07-13
| | PawnSac: < Patriot: White is up a pawn for a piece so a draw is a good outcome. There are so many forcing candidates. OTB I would probably have to try 25.Qxe4. > White has sacrificed a piece and can't go in for a game of attrician and slow maneuvering when black will organize and use his material for advantage. White must play energetically before he loses the initiative and the end game. The black queen has an eye on the h4-d8 diagonal, so 25.Qxe4 can be countered with Rd8. Black would like to trade a pair of rooks but with the white Q on e5 before he can play Rd8 he needs to safeguard the other rook. Rg8 comes to mind, but as i stated above, after g5 this is no longer possible. So < 25.g5 bringing another soldier into the attack on the king is clearly the best move. > Since the rook can't abandon the first rank, and the only available square is d1, yet the rook belongs behind the pawn, it seems that g5 is also the ONLY move! |
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Apr-07-13
| | PawnSac: well, the only GOOD one that is |
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Apr-07-13
| | PawnSac: It is also interesting that in agb2002's comment and mine above, g6! was the ace in the hole, an interesting feature of the position, and without it, white would be lost. |
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| Apr-07-13 | | Patriot: <PawnSac> Those are some very good points indeed! And I agree about 25.g5 seeming to be the only move here. |
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| Apr-07-13 | | morfishine: <(AylerKupp> & <agb2002> Thanks for the follow up guys! I felt a bit sheepish as my power went out and though I could see fairly quickly Qc7 was insufficient I couldn't post anything for a couple of hours |
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| Apr-08-13 | | stst: One line:
25.Qd6+ Kg8
26.g5 Bc8
27.Re7 R5
28.g6 fxg6
29.Rxg6+ Kh8
30.Qd4+ e5
31.Qg1 Qxe7
32.Rg8+ Kh7
33.Qg6+ Qg7
34.Qxg7# |
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Apr-08-13
| | AylerKupp: <agb2002> You're right, 26.Qf6 seems better than 26.Qc7 since it prevents the ...Qf2 defense. After 26.Qf6 Critter 1.6a evaluates Black as being busted with an eval of [+6.78], d= 25 after your suggestion of 26...Rh7 27.Qe7+ Kg8 28.g6 Qxe7 29.gxh7+ Kxh7 30.Rxe7
click for larger viewSo perhaps instead of 25...Rh5 and 26...Rh7 we try 25...Rh7 immediately to protect f7 against both 26.Qc7 and 26.Qf6.
click for larger viewBut then instead of those moves 26.Qd6+ is crushing. At a lowly d=22 Critter evaluates the position at [+12.50] after 26.Qd6+ Kg8 27.g6 Qh6+ 28.Kb1 fxg6 29.Qxe6+ Kf8 30.Qd6+ Ke8 31.Rd1 Bd3 (the horizon effect in action!) 32.Rxh7 Qxh7 33.Qc6+ Qd7 34.Qxa8+ Ke7 35.cxd3 e3 36.Qe4+ etc.
click for larger viewSo maybe 25...Qh2 as in the game is necessary after all to prevent 26.Qd6+. Critter agrees, considering it the least of all evils but at d=27 it considers that Black is busted, evaluating the position at [+6.75] after 25...Qh2 26.Qc5+ Kg8 27.g6 f6 28.Qb6 Qxg1+ 29.Qxg1 e3 30.Qxe3 Rh1+ 31.Rd1 Rxd1+ 32.Kxd1 Kg7 33.Qxe6 Ra7 34.a4 Bf1 35.Qe4 Ba6 36.Qe3 Rb7 37.Qh3 f5 38.Qxf5 Re7 39.b4 Bb7 40.b5 Be4 41.Qf4 Bxg6 42.b6 Rf7 43.Qd4+ Kg8 44.a5 Bf5 45.Qc4 Kf8 46.a6 Rd7+ 47.Ke2 Re7+ 48.Kd2 Be6 Critter's second "best" line starts with 25...Qh1 which gives you an idea of how bad Black's prospects are, being evaluated at [+9.12]. I won't bother to post it. Critter's third "best" line? It indicates mate in 42(!) after 25...Qh3. So, while I might have answered <morfishine>'s question of wanting to know how an engine defends after 25.g5 Rh5 26.Qc7 and might have been right in concluding that in that case White is busted, it looks like the reverse is true after your suggested 25.g5 Rh5 26.Qf6 or my attempt at improvement after 25.g5 Rh7 26.Qd6+. It is Black who is busted and Zhou Jianchao actually played the best move after25g5, 25...Qh2. And he had the good sense to quickly realize that the game was over after only 3 more moves. |
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Apr-08-13
| | AylerKupp: <<morfishine> "...my power went out and though I could see fairly quickly Qc7 was insufficient I couldn't post anything for a couple of hours.> That's a good excuse. I'll have to remember that one next time that I make an inferior suggestion. :-) P.S. It seems like a good reason to get an uninterruptible power supply. :-) |
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| Apr-08-13 | | vinidivici: <PawnSac>
<After 25.g5 ..Rg8 is now out of the question since
26.Qd6+ Kg7 27.Qxe6! Rgf8 28.g6! with a deadly attack.>Your proposed line after 25.g5 is 25...Qd6+, yes its also good. But also my proposed line 25...Qf6 also good.
So the it has multiple ways to win.
So its a matter of taste. |
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| Apr-10-13 | | morfishine: <AylerKupp> I hate to make excuses, but it is true and so I stand by the comment, warmed by your anointing the comment as a 'good excuse' :) |
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Apr-12-13
| | AylerKupp: <morfishine> The best part of your excuse is that I will have a lot of chances to use it during the upcoming BOB-4 game! And, since we're on the same team, you will get to see my inferior suggestions time and time again. |
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Kibitzing
sac: 21.Nxb5