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| Nov-27-10 | | David2009: It is interesting to play today's puzzle colours-reversed out against Crafty End Game Trainer:
click for larger view T Henrichs vs M Prusikin, 2007 colours reversed - White to move and win.
EGT link: http://www.chessvideos.tv/endgame-t... Be prepared for a long end game with unbalanced material. <Once>'s splendid post (linked above) gives a clue but there may be other winning strategies. Beware of elephant traps! |
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| Nov-27-10 | | patzer2: <MiCrooks: The initial move, Nfg4 is pretty obvious, but it wasn't clear to me how Black proceeds when White declines the sacrifice.> Yes, my thoughts exactly on this Saturday puzzle, since 23...Nfg4+!! is the only move to create winning chances and exploit Black's King position. The accepted line is not easy, and the declined variations create even greater complications. Here's some analysis with Fritz 10:
<23....Nfg4+ 24. hxg4> (24. Kg3 Rh6! 25. d6 f5 26. Bxe5
Nxe5 27. Kh2 f4 28. d7 Nxd7 29. Rd5 g4 30. exf4 Nf6 31. Rg5 gxh3 32. g4 e3 33. Qe2 Ne4 34. Rd5 Nxf2 35. Bb1 Nxg4+ 36. Kh1 Nf2+ 37. Kh2 Rh4 38. Rg1 Ng4+ 39. Kh1 h2 40. Rg2 Nf2+ 41. Rxf2 exf2 42. Qxf2 Qg4 43. Bd3 Re1+ 44. Bf1 Rc1 45. Re5 Qd1 46. Re8+ Kf7 47. Re7+ Kf8 48. Rf7+ Kxf7  ; 24. Kg1 Nf3+! 25. gxf3 Nh2! 26. fxe4 Qxh3 27. f3 Nxf3+ 28. Rxf3 Qxf3 29. Rf1 Qg3+ 30. Qg2 Qxe3+ 31. Qf2
Qxc3 32. Qxf7+ Kh7 33. Qf3 Qe5 34. Qf5+ Qxf5 35. Rxf5 Rxe4 ; 24. Kh1 Nf3 25. Bxg7 Qf5 26. Bb3 f6 27. Ba4 Red8 28. Bh6 Nxh6 29. Rb1 Kg7 30. Bd1 Nf7 31. Bxf3 exf3 32. Kg1 fxg2 33. Kxg2 Rh8 34. Rh1 Ne5 35. Qe2 Rh4 36. f3 Rxc4 37. e4 Qf4 38. Rb3 a6 39. Rd1 b5 40. Re1 Rd4 41. Rd1 Rxd1 42. Qxd1 c4 43. Rc3 f5 44. Qc1 Nd3 45. Qxf4 Nxf4+ 46. Kf2 Kf6 ) <24... Rh6+ 25. Kg1 Nf3+!> This followup forces mate, and is the clearest winning continuation. Black appears to win after 25... Qxg4!? 26. Bxe5 Qh5 27. f3 exf3 28. Rxf3 g4 29. Rf5 Qh1+ 30. Kf2 Qxd1 31. Qe2 Qc1 32. Bb3 Rh1 but it's more complicated, too risky and not as clear as the forced mate in the game continuation. <26. gxf3 exf3 0-1>
Black resigns in lieu of 27. Be5 Qxg4+ 28. Bg3 Rh1+ 29. Kxh1 Qh3+ 30. Kg1 Qg2#. |
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| Nov-27-10 | | gofer: <23 ... Nf3+>
Suddenly, white is caught in a horrendous position and until that it probably didn't feel too bad... 24 Kg3 Qf5! (threatening Nh5#!) 24 gxf3 Qxf3+ 35 Kh2 Ng4+ 36 Kg1 Rh6 mating soon 24 Kh1 g4! (hxg4 Qxg4 mating or Rg1 Nxg1 25 Rxg1 gxh3 26 Qe2 Qf5 winning) <24 gxf3 exf3>
We have our "killer" pawn. It controls e2 and g2. It stops the black queen from coming to it's king's rescue along the 2nd rank as Pf2 is stuck. It has also freed up e4 allowing Ne4 and Re4! Both of which
allow the rooks to sweep across to the h file and attack Ph3! So its all over! One continuation is as follows... 25 Bxf6 Rxf6
26 Rg1 Re4
27 Rg3 Rh4
28 Rh1 Rh6 29 Rxf3 Rxh3+ 30 Rxh3 Qxh3+ 31 Kg1 Qxh1#
28 Qe5 Rh6 29 Qxg5 Rxh3+ 30 Rxh3 Qxh3+ 31 Kg1 Qxh1# Time to check...
===
I considered 23 ... Nfg4+, but couldn't see the killer blow if white
simply replied 24 Kh1, now 24 ... Nf3 is no longer check and white gains
a tempo to play Bxg7... ..interesting position though... |
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| Nov-27-10 | | Patriot: I spent a lot of time on this late last night and decided to look a bit longer this morning. After looking over my candidates I decided on 23...Nfg4+. There is no risk involved since there is a forced mate if white plays 24.hxg4 as everyone has already analyzed. The toughest defense seemed to be 24.Kg3. After that I didn't know how black would continue. 24...Nxe3 seems to help white more than anything since 25.fxe3 opens the f-file for the rook. So probably just a quiet move such as 24...Rh6 or 24...Rf6 or 24...Qf5--I'm not sure. White gave black too easy of a win here. |
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| Nov-27-10 | | mrsaturdaypants: 23...Nfg4+ looks like it does all the right things: puts white's king in check, opens the way for the rook to come to the h-file, and aids the queen's entry to g4 in many lines. Hard to believe that wouldn't be the right first move. I can't even see the other good candidates. (a) 24 hxg4, Rh6+, and if 25 Kg1, Nf3+ 26 gxf3 exf3, and white is helpless to prevent Qg4 and mate. If 25 Kg3, Qg4# looks satisfactory. So, (b) 24 Kh1 Rh6, and I don't see a definitive combination from black, but the line looks winning. (c) 24 Kg1 Nf3+, and if 25 gxf3, exf3 looks decisive, while if 25 Kh1, Rh6. In neither the (b) nor the (c) lines am I seeing the unavoidable path to victory for black, but I know which side I'd rather have. Time to check. |
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| Nov-27-10 | | knight knight: 24. Bxe5 is threatened. That g4 square looks tasty. Let's consider 23...Nfg4+ a) 24. hxg4 Rh6+ 25. Kg1 (25. Kg3 Qg4#) Nf3+ 26. gxf3 exf3 27. Be5 (27. Rd4 cxd4) Qxg4+ 28. Bg3 Qh3 mate next move b) 24. Kg3 Qf5 25. Bxe5 Qh7 white is toast
c) 24. Kg1 Nf3+ 25. gxf3 Nh2! 26. Kxh2 Rh6 white is toast d) 24. Kh1 Nf3 25. gxf3 Rh6 26. Rg1 (26. Kg2?? Nh2 27. f4 Qxh3+ mating) Rxh3+ 27. Kg2 Rh2+ 28. Kg3 Qf5 I think white is toast, looks pretty horrible That'll have to do, there are probably better defences. Also looked at 23...Nf3+ and 23...Qf5 and a couple of wild ideas 23...Qxh3+ and 23...Kh7 (to g6, so Rh8 is possible), but couldn't get anything out of them. |
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Nov-27-10
 | | Jimfromprovidence: The excellent analysis by <Nullifidian> convinced me that after 23...Nfg4+ both 24 Kh1 and Kg1 don't work, but after 24 Kg3 I’m not sure what works. <Once> has <24. Kg3 f5 25. Bxe5 Nxe5 with f4, Rh6 and g4 to come>. That looks pretty good but <Once> leaves it upon his devotees to work out the messy details after 25...Nxe5 below.
click for larger view
<knightknight> has <24. Kg3 Qf5 25. Bxe5 Qh7 white is toast> but after 24…Qf5 (seeing the spectacular 25 …Qh7 followed by 26….Qh4#) white has 25 Rh1!.
click for larger viewNow, 25…Qh7 does not work because 26 hxg4 wins a piece. So the line of <Once> is the one to beat right now. |
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| Nov-27-10 | | knight knight: Good spot <Jimfromprovidence> (23...Nfg4+ 24. Kg3 Qf5 25. Rh1!) It still looks amazing that white can survive the second diagram (if indeed he can), black hasn't even sacrificed any material! |
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| Nov-27-10 | | agb2002: Black has two knights for the bishop pair.
White threatens 24.Bxe5.
The rook on d6 would be better placed on h6. This suggests 23... Nfg4+: A) 24.hxg4 Rh6+ 25.Kg1 (25.Kg3 Qxg4#) Nf3+ 26.gxf3 Qh3 and mate next. B) 24.Kg1 Nf3+
B.1) 25.gxf3 Nh2
B.1.a) 26.Kxh2 Rh6 27.Kg1 Qxh3 and mate next.
B.1.b) 26.fxe4 Nf3+ (26... Qxh3 27.f3 looks unclear) 27.Kg2 Nh4+ 28.Kh2 Nf3+ and Black has perpetual at least. B.1.c) 26.Be5 Nxf3+ 27.Kg2 Nxe5 and Black has won a pawn and keeps the attack. B.2) 25.Kh1 Ngh2 26.Rfe1 (26.gxf3 Qxh3 - +) Rh6 with the threat 27... Rxh3. C) 24.Kh1 Nf3
C.1) 25.hxg4 Rh6#.
C.2) 25.gxf3 Rh6 26.Kg2 Nh2 followed by Qxh3+.
C.3) 25.Bxg7 Ngh2 followed by Rg6 and Rxg7 or Rh6, keeping the attack. That's all I can do now. |
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| Nov-27-10 | | agb2002: I found a few hallucinations in my solution text before posting but 26... Qh3 in line A escaped. Bloody saturdays... |
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| Nov-27-10 | | wals: Today I picked the right Knight to move and the right square to move to, but didn't fully complete all moves. Rybka 4 x 64 depth: 21 : 7 min :
1. (-#4): 27.Be5 Qxg4+ 28.Bg3 Rh1+ 29.Kxh1 Qh3+ 30.Kg1 Qg2# 2. (-#3): 27.Rd4 cxd4 28.Re1 Qxg4+ 29.Kf1 Rh1#
depth: 18 : 4 min :
Black error
(  0.40):15...Bg6. Best, exf3, -=0.11.
depth: 17 : 6 min :
White error
(=0.04):20.Rbd1. Best, Bb3, 0.42.
Nxg6, 0.42.
depth: 20 : 7 min :
White blunder
(-#7):24.hxg4. Best, Kh1, -1.26.
Move 20 was White's downfall. |
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Nov-27-10
 | | scormus: <Once .... "They don't fight wars properly any more" ...> Absolutely brilliant! <Colonel Potherington-Smythe> I knew him well, taught me all I know. Had only one strategy - direct assault. |
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| Nov-27-10 | | LIFE Master AJ: Hmmmm.
As I suspected, White made the task MUCH easier by capturing on g4. (The last thing the defender <normally> should do is to open lines.) The proof?
</= 24.Kg1? Nf3+!; 25.gxf3 Nh2; 26.fxe4 Qxh3; 27.f3 Nxf3+; 28.Rxf3▢, White had no choice. (Worse is: </= 28.Kf2? Qh2+! 29.Kxf3 g4+; 30.Kxg4 Rg6+; 31.Kf3 Rg3+; 32.Kf4 Qh4+; and mate next move. ) 28...Qxf3; 29.Rf1 Qxe3+;
" " (Black has a winning attack.)
click for larger view The computer shows that White has to play 30.Qf2, QxB/c3. (30.Rf2?! fails to 30...RxP/e4.) *****
</= 24.Kh1?! Nf3 25.Bxg7 Nge5 26.Bxe5 Rxe5 27.g4 Qc7 28.Qe2 Rexd5 29.cxd5 Rh6 30.d6T Rxd6 31.Rxd6 Qxd6 32.Qxf3 exf3; " " (Black has a won ending.)
click for larger view *****
White still loses, but his best chance was: 24.Kg3! Rh6 25.d6 f5 26.Bxe5 Nxe5 27.Kh2 Qe6 28.Rh1 g4 29.g3 gxh3! 30.Rhf1 f4 31.exf4 Ng4+! 32.Kh1 e3 33.Qe2 Nxf2+ 34.Rxf2 exf2 35.Qxf2 Qg4 36.Bb3 Re2 37.d7 Rxf2 38.d8Q+ Kh7 39.Qd3+ Rg6 40.Rf1 Qxg3! 41.Qxg3 Rxf1+ 42.Kh2 Rh1+! 43.Kxh1 Rxg3; Black has an easily won ending. " " 
click for larger view |
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Nov-27-10
| | scormus: <LMAJ .... White still loses, but his best chance ...>
Glad I didnt waste all day trying to find that lot!
When I saw the home page position the only reply I wanted to consider was hxg4. I couldnt believe my eyes when I saw thats what W actually played. |
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| Nov-27-10 | | LIFE Master AJ: <<<<<scormus> Yes, White> stepped on his <ahem>> "neck-tie" > ... that time around.> |
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| Nov-27-10 | | Patriot: <wals> I disagree about move 20 being white's downfall. Four tenths of a pawn difference isn't necessarily winning for white. Of course, fractions here and there can add up to big advantages over time. My problem with computer analysis is that unless a human player misses a tactical opportunity or loses to one, it's like comparing a mathematician to a calculator. I think a lot of human decision making rests on two major components: 1) time remaining on the clock; and 2) criticality in the position. Based on analysis with Fritz in my own games, my biggest mistakes are not the fractional pawn differences that Fritz loves to point out. It's that I'm not doing a good job balancing time management with analysis and criticality of the position. I'm spending several minutes on moves that should have taken no more than 20-30 seconds. In move 20, black isn't really threatening anything and neither is white. I admit 20.Rbd1 does seem strange and probably is a time-waster. But 20.Bb3 seems odd. I would look at a minority attack starting with 20.a4 or just firming up the b5 square. Perhaps ...b5 is what white was worried about so he added extra defense to d5. |
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| Nov-27-10 | | WhiteRook48: i had Nfg4+ but i assumed the follow-up to be Qxg4 |
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| Nov-27-10 | | M.Hassan: "Very Difficult" Black to play 23.....
White has lost 2N+p & Black 2B+p.Assumed to be equal.
I wasted quite long time trying to continue with the movement of e Knight like 23....Nef3+ and 23....Neg4+ and it did not work out until I looked at the solution and saw that it is Knight "f" movement
So, I did not solve it. Period |
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| Nov-27-10 | | chess enigma: I am on a roll, got it in 10 minutes. |
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| Nov-27-10 | | RandomVisitor: After 17...Rfe8:
click for larger view Rybka 4:
<[+0.20] d=25 18.Rab1> h5 19.Bxe5 Rxe5 20.Qb2 Re7 21.Nxg6 fxg6 22.Bb3 g5 23.Bd1 Rf8 24.Qd2 Ref7 25.a4 Qe5 26.Rb5 g4 27.hxg4 Nxg4 28.Bxg4 hxg4 29.Qb2 Qc7 |
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| Nov-27-10 | | RandomVisitor: After 23...Nfg4+:
click for larger view
Rybka 4
<[-2.16] d=18 24.Kh1> Nf3 25.Bxg7 Nge5 26.Bb1 Qf5 27.Bxe4 Qxe4 28.Bxe5 Nxe5 29.f3 Qxc4 30.e4 Qa4 31.Qc1 f6 32.f4 Ng6 33.fxg5 fxg5 34.Qxg5 Rxe4 35.Qg3 Re5 36.Rd3 Qe4 37.Rdf3 Kg7 |
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| Nov-27-10 | | RandomVisitor: After 21...hxg6:
click for larger view Rybka 4:
<[+0.00] d=21 22.Bb1> Qd7 23.Bxe5 Rxe5 24.Qc3 Rg5 25.f4 Rh5 26.Bc2 g5 27.Rd2 g4 28.Bd1 Rh4 29.hxg4 Nxg4 30.Bxg4 Rxg4 31.Qe5 f5 32.Rfd1 Rg3 33.Re1 Rgg6 |
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| Nov-28-10 | | wals: <patriot> Thank you for your comments. |
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| Nov-30-10 | | tacticalmonster: 1) White threatens Bxe5 and the Q and B battery creates counterplay along the a1-h8 long diagonal 2) White's light square bishop is stuck out of play on the queenside. This creates light square weaknesses on the kingside (f3-g2-g4-h3 complex) 3) Black's d6 rook blockade the protected d5 passer but can potentially swing over to h6 along the third rank 4) Black can potentially sacrifice one or both knights while giving check on f3 or g4. a) The f3 check blockade white's f-pawn, remove the defender (g2 pawn) of h3 pawn, create a powerful f3 pawn nail in the White's position and create a half-open e-file for the e8 rook. b) The g4 check open up Black's third rank for the d6 rank, open up the h-file for Black's major pieces and create a entry point (g4) for the Black queen. c) White can potentially decline the sac with Kh1, Kg1 or even Kg3. Candidate: 23 a) Ng4+ and b) Nf3+
a1) 24 hxg4? Rh6+ 25 Kg1 Nf3+! 26 gxf3 exf3 27 Be5 Qxg4+ 28 Bg3 Qh3 29 any Qh1# a2) 24 Kh1 Rh6 25 d6! Qf5 26 d7 Nxd7 27 Rd5- White breaks up Black's attack a3) 24 Kh1 Qf5 25 Bb1 Nf3 26 Qe2 Ngh2 27 Rg1 g4! 28 Bc2 Nxg1 29 Kxg1 Nf3+ 30 Kf1 (30 Kh1 Rh6 31 d6 g3 32 Qxf3 Rxh3+ 33 Kg1 gxf2+ 34 Qxf2 Rh1+ 35 Kh1 Qxf2  ) 30...Rh6 31 d6 gxh3 32 Qxf3 exf3! 33 Bxf5 hxg2+ 34 Ke1 Rh1+ 35 Kd2 Rxd1+ 36 Kxd1 g1=Q+ |
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| Aug-27-23 | | Saniyat24: such a helpless White king...! |
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