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| May-05-17 | | Iwer Sonsch: <23...Nb3+!>
(24.Kb1 Nd2+ 25.Kc1 Nxf1)
(24.Kd1 Nxf1 and Black's defense holds)
(24.axb3 Rxa1+ Kc2 Rxf1)
<24.cxb3 Qe3+ 25.Kd1 Qd3+> (26.Kc1 Rc8+ mating)
<26.Ke1 Re8+ 27.Qxe8+> (forced) <27...Kxe8> wins material. Also, White's pawns look vulnerable with White only having rooks. Kinda too easy for a Friday, as a better line was not to exspect and this one doesn't appear to have any flaws. |
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| May-05-17 | | goodevans: I looked at 23...Nb3 for a long time but couldn't get past the complications that would ensue after <24.Kd1>. I see from <Patzer2>'s post that Stockfish chooses 24.Kd1 as the best defence to Nb3. |
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| May-05-17 | | gofer: While Ra1 is stuck in the corner, white is effectively two pieces down,
so giving up our knight is not an issue if it is a worthwhile sacrifice... <23 ... Nb3+>
24 Kb1/Kd1 Nxa1
25 Qb5+ Kc7 
24 axb3 Rxa1+
25 Kd2 Bh6+
26 Kd3 Qe3+
27 Kc4 Qd4+
28 Kb5 Rxf1
<23 cxb3 Qe3+>
24 Kb1 Qd3+
25 Kc1 Rc8+
26 Qc5 Rxc5#
24 Kc2 Rc8 25 Kd1 continues as below but one move later... <24 Kd1 Qd4+>
Position is everything! I originally tried Qd3+, but that
seems to lead nowhere whereas Qd4+ keeps the white king in
a huge bind and also "connects" the queen with the DSB! 25 Kc1/Kc2 Rc8+
26 Kb1 Qd3#
<25 Ke2/Ke1 Re8+> <26 Qxe8 Kxe8>  The queen is going to cause havoc and connecting the rooks is difficult... ~~~
Hmmm, okay, now I am intrigued which is better!? <24 ... Qd4+>
or
<24 ... Qd3+>
What do our silicon friends say!? |
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| May-05-17 | | Iwer Sonsch: <gofer> Qd3+ threatens the rook and mate. But apparently, 24...Qd4+! is still stronger (-2.12 @depth 26 vs. -1.63 @depth 27 after 27...Kxe8). In both cases, White should have played 28.Rf2. |
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| May-05-17 | | Iwer Sonsch: Apparently, White fares better with 24.Kd1 Nxa1 25. Qb5+! Kc7 26.Rf4!
click for larger view
26...d5 (other moves draw) 27.Rxf8 Rxf8 28.Qc5+ Qc6 29.Qe7+ Kb6 30.Qxb4+ Ka6 31.Qxf8 Qxc2+ 32.Ke1 Qc1+ 33.Kf2 Qxb2+ 34.Kf3 (-0.77 @depth 24). |
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| May-05-17 | | Iwer Sonsch: Today's puzzle solution is 23...Bh6! 24.Kd1 Kc6 25.Qe2 Qg8! 26.Rf2 Re8 27.Qh5 Qh8 28.c3 bxc3 29.bxc3 Re3 30.Rf3 Re1+! 31.Kxe1 Bd2+ 32.Kxd2 Qxh5. We all, including chessgames.com, failed to solve this Sunday+ puzzle. |
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| May-05-17 | | thegoodanarchist: In the game continuation, if White plays 33.Rxg7, how does Black win? I can't find it. |
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| May-05-17 | | thegoodanarchist: And has anyone besides me wondered why so many puzzles come from games played in 2007? |
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| May-05-17 | | Walter Glattke: Refined, 26.-Rxa2 27.Rc4+ / 26.-Qe5 27.Rf7+, play against the open king! |
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| May-05-17 | | Walter Glattke: theg Anar: patzer 2 descrived above queen moves, those win the Rg7 with check. |
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| May-05-17 | | Walter Glattke: 23.-Nb3 24.Kd1 Ra5 25.Rf7+ Kc6 26.Qf3+ Rd5+ good for black, 25.Rf7+ not strong enough. |
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| May-05-17 | | Iwer Sonsch: <Walter Glattke> 23...Nb3+ 24.Kd1 Ra5 25.Qf7+ Qxf7 26.Rxf7+ Ke6 27.Rxf8 Rd5+ 28.Ke1 Nxa1 is equal. |
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| May-05-17 | | Walter Glattke: Equal material, 3 pawns for a knight, but , so as 24.Kd1 Nxa1 or 24.cxb3,
all a won ending after a long time, I think. |
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| May-05-17 | | Iwer Sonsch: <Walter Glattke> Stockfish suggests either 29.Rf2 Ra5 30.b3 Rxa2 31.Kd1 d5 32.Rd2 (0.00 @depth 33), 29.Re8+ Kf6 30.Re2 (0.00 @depth 33)
or 29.Rc8 Ra5 30.a3 b3 31.bxc3 Nxc3 (-0.05 @depth 33). Now how do you think Black is winning? |
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May-05-17
 | | benveniste: I found ♗h6+. After ♔d1 I'll play ♔c6. |
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| May-05-17 | | Iwer Sonsch: <benveniste> is the new champ. |
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| May-05-17 | | lost in space: A hard nut:
23...Nb3 24. cxb3
24. Kd1?! Nxa1 25. Qb5+ Kc7 26. Rf4 d5 (26...Nxc2?! 27. Rc4+ Kd8 28. Qb6+ Ke7 29. Qb7+ Kf6 Qf3+ =) 27. Rxf8 Rxf8 28. Qc5+ Qc6 29. Qe7+ Kb6 30. Qxb4+ Ka7 31. Qxf8 with a white edge but a long way to win this). 26. Kd1 seems to be playable also 24..Qe3+
(not 24...Rc8+ 25. Kd1 and no progress for Black and also not 24...Bh6+ 25. Kd1 and no progress) 25. Kc2
(not 25. Kb1 --> mate in 3 after 25...Qd3+ 26. Kc1 Rc8+ 27. Qc5 Rxc5#; 25. Kd1 Qd4+ leads to there same position as the my mainline with 25. Kc2) 25... Rc8+ 26. Kd1 Qd3+ 27. Ke1 Re8+ 28. Qxe8+
(not 28. Kf2 Qe3#)
28...Kxe8 29. Rf3
click for larger viewIs this won for Black? I don’t think so. Better for Black yes, but won?! From a material point of view White has 15 points, Black 14 points, Black has more active pieces with is overcompensating his material minus....I would not give up here as Black, so even though I though long about the puzzle I don’t think I found the solution. Sigh. |
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| May-05-17 | | Walter Glattke: Iwer 29.Re8 Kd7 30.Re2 Re5
29.Rf2 Ke5
29.Rc8 Kd7 30.Rc4 Rg5
All I can say is, that black can improve his Position, and stockfish has over elo 3000, black initiative, but no win against a Computer, to try against human Players. |
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| May-05-17 | | patzer2: The opening here is quite interesting. In this Sicilian Najdorf (B96), Black demonstrates he's up for a sharp theoretical and tactical battle, even before castling, with 8...b5 (diagram below)
click for larger viewWhite's response with 9. f4!? b5 10. Ncb5 sacrifices a Knight for an attacking position (diagram below) 
click for larger viewand enters a wild minor variation of this line (B96) which is extremely tactical and sharp. Yet the computers evaluate the position as level. Of 24 games in the chessgames.com opening explorer in this 9. f4!? b5 10. Ncb5 (B96) line, White won 6, Black won 8, and 8 were draws. All 24 games continued with correctly accepting the positional Knight sacrifice offer with 10...axb5. However, not all 24 games continued with the reply 11. Bxb5+ fxe6 12. Bxb5 = (0.00 @ 29 depth, Stockfish 8.) White also has the option of further complicating things with 11. fxe6 Be7 12. Nf5!? = to  (-0.26 @ 29 depth, Komodo 10.1) as in White's win in U Atakisi vs B Gundavaa, 2006. Of the 24 games with the Knight sacrifice 10. Ncb5 axb5, White played 11. Bxb5+ in 17 games and 11. fxe6 in 7 games. Even though the computers slightly favor 11. Bxb5+, the element of surprise has given White an even result with three wins, three losses and one draw in the 11. fxe6 line. P.S.: Most GMs prefer to avoid these wild complications altogether after 8...b5. So after 8...b5, they avoid the 9. f4!? b5 10. Nc5 axb5 unclear lines by playing the more popular moves 9. 0-0-0 = to  as in the sharp drawn game K Miton vs M Vachier-Lagrave, 2008 or 9. Bxf6 (the computer choice) as in White's win in Shirov vs I Papaioannou, 2009. My preference after 8...b5 would be to avoid the complications and play 9. 0-0-0 or 9. Bxf6, though 9. f4!? looks like a fun try for skittles or blitz. |
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| May-05-17 | | tea4twonty: 23..Bh6+ 24.Kd1 Kc6 25.Qe2 Qg8 26.Rf2 (26.Qh5 Qc4 27. Rf5 Rg8) 26..Re8 27. Qh5 Re5 28. Qf3+ Re4 |
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| May-05-17 | | agb2002: Black has a bishop and a knight for a rook and three pawns. The position of the white king and rooks lead to consider 23... Nb3+: A) 24.axb3 Rxa1+ 25.Kd2 Bh6+ (25... Rxf1 26.Qb5+ and 27.Qxf1, unclear) 26.Kd3 (26.Qxh6 Qxh6+ followed by Rxf1, etc.) 26... Qe3+ 27.Kc4 Qe4+ 28.Kb5 Qc6+ 29.Kxb4 Bd2#. B) 24.cxb3 Qe3+
B.1) 25.Kb1 Qd3+ 26.Kc1 Rc8+ 27.Qc5 Rxc5#.
B.2) 25.Kc2 Rc8+ 26.Kd1 Qd3+ 27.Ke1 Re8+ 28.Qxe8 (28.Kf2 Qe3#) 28... Kxe8 with more or less balanced material but the queen and bishop will attack the white king and pawns. For example, 29.Rf3 Qd4 30.Rd1 Qg1+ 31.Rf1? Qe3#. B.3) 25.Kd1 Qd3+ as above.
C) 24.Kb1 Nd2+ 25.Kc1 Nxf1 26.Qb5+ Kc7 27.Qxf1 Bh6+ C.1) 25.Kb1 Rf8 26.Qd1 (26.Qg(h)1 Qe2 wins) 26... Qc4 27.b3 Rf1 28.bxc4 Rxd1+ 29.Kb2 Bg7+ wins. C.2) 25.Kd1 Qg4+
C.2.a) 26.Ke1 Re8+ 27.Kf2 Rf8+ wins.
C.2.b) 26.Qe2 Qd4+ 27.Qd3 (27.Ke1 Qg1+ 28.Qf1 Re8+ 29.Kd1 Qxf1#) 27... Qg1+ 28.Ke2 Re8+ 29.Kf3 Re3+ 30.Kg4 (or 30.Qxe3 Qxe3+, winning) 30... Qxg2+ and mate next. C.2.c) 26.Qf3 Qd4+ 27.Ke1(2) (27.Qd3 transposes to C.2.b) 27... Re8+ 28.Kf1 Rf8 wins. D) 24.Kd1 Nxa1 seems to win decisive material without compensation for White. For example, 25.Rf7+ Be7 26.Qb5+ Kc7 27.Rf1 Qxa2 - + [b+n vs 2P]. |
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| May-05-17 | | patzer2: Correction: In the final position, if 33. Rxg7 then 33...Qf4+ 34. Kg1 (34. Ke2 Qe5+ ) 34...Qd4+ <not 34...Qd1+> picks off the Rook on g7 with a Queen fork (double attack.) |
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| May-05-17 | | devere: This is a problem that any weak chess player is likely to solve correctly. 23...Bh6+ is the obvious move for the "always check, it may be mate" crowd, and it also happens to be the best winning move, although the somewhat more subtle 23...Kc6 also wins. Those of us with more chess skill are likely to see 23...Nb3+, and probably overlook that after 24.Kd1 Nxa1 25.Qb5+ Kc7 26.Rf4 Black will have a very hard time winning. This is a diabolically humorous problem. I'd love to see what Magnus Carlsen would do in this position over the board with his clock ticking. |
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| May-05-17 | | Iwer Sonsch: <devere> In a rapid game, even Stockfish would have played 23...Nb3+. |
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| May-05-17 | | swclark25: I matched the game line thru 26)...Re8+ but failed to see 27)Qxe8+ Kxe8 Why did White resign with the game line?
<patzer2> thanks for showing Black's response to 33) Rxg7 I will have to study <Iwer Sonsch: Today's puzzle solution is 23...Bh6! 24.Kd1 Kc6 25.Qe2 Qg8! 26.Rf2 Re8 27.Qh5 Qh8 28.c3 bxc3 29.bxc3 Re3 30.Rf3 Re1+! 31.Kxe1 Bd2+ 32.Kxd2 Qxh5. We all, including chessgames.com, failed to solve this Sunday+ puzzle.> |
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Kibitzing
sac: 17...Nd7