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Aug0208   Dr. J: In <tpstar>'s line 26 ... Bf6 27 Nxf6 gxf6 28 Rxh6+ Kg8 then 29 Qc5+ (instead of Qh3) wins directly. Of course Black can decline to recapture at move 27, remaining ahead the exchange, but I think that then the Black Kside can be defended against the continuing threats. Hmm, I had four words in a row beginning with "th" :) 

Aug0208   Dr. J: <RandomVisitor> your analysis suggests Rybka does not like White's combination very much. How does it evaluate the game continuation 24 Rh1 exd4 25 g6? 

Aug0208   RandomVisitor: <Dr.J>Rybka likes 24.Rh1 exd4 <25.g6> when the position is forced: click for larger view Rybka2.3.2a.mp.x64: <15ply> 1. (6.70): 25...h6 26.Bxd4 Kg8 27.Rxh6 gxh6 28.Qh3 Bf6 29.Qe6+ Kh8 30.Nxf6 Qg7 31.Qd6 Rad8 32.Nd7 

Aug0208   lost in space: Another tricky one.
The very obvious move 24. Ne6 Qxc6 25. Nxf8 Bxf8 26. g6 h6 fxe5 is leading to a = position. Other options: Rh1, Qh3, g6.
I was going for this line:
24. g6 exd4
other options for Black: 24...Bc8 25. Qh1 h6 26. fxe5 with the threat Bxh6 and win for white.. or 24...h6 (best move?!) 25. fxe5 Qxe5 26. Qh1 (obvious threat) Kg8 27. Bf4 Rxf4; advantage white, but not 100% won 25. Qh3 h6 (foreced) 26. Bd4 (Threat: Qxh6) Bf6 (best I found) 27. Nxf6 Qxc6 28. Qxh6 gxh6 29. Nd5+ Rf6 30. Bxf6 Qxf6 31. Nxf6 Time to check.


Aug0208   Dr. J: <RV> I'm stlll puzzled. First, why did Rybka prefer 24 Rh1 dxe4 25 Bxd4 over 25 g6 in your original post? And secondly, in your line 24Rh1 dxe4 25 g6 h6 26.Bxd4 Kg8 27.Rxh6 gxh6 28.Qh3 Bf6 (instead of "resigns ?!") 29.Qe6+ Kh8 30.Nxf6 Qg7 31.Qd6 what happens after 31 ... Qxg6? 

Aug0208
  Once: Nope  didn't get this one. I looked at several possibilities  24. g6, 24. Ne6, 24. Rh1 and 24. Qh3. Couldn't get any of them to work in the 510 minutes that I allow myself (to mimic the time controls in a real game). I got a little too worried about the pin on the knight after Qxc6 and Bb7. 

Aug0208   ozmikey: <Dr. J><And secondly, in your line 24Rh1 dxe4 25 g6 h6 26.Bxd4 Kg8 27.Rxh6 gxh6 28.Qh3 Bf6 (instead of "resigns ?!") 29.Qe6+ Kh8 30.Nxf6 Qg7 31.Qd6 what happens after 31 ... Qxg6?> I think White can do better: instead of 31. Qd6, 31. Be5 looks more logical, and then on 31...Qxg6 32. f5! looks winning (32...Qf7 33. Ng4+). 

Aug0208   johnlspouge: I found the key move 24.Rh1, but on acceptance of the sacrifice followed it with the primary variation 24.Rh1 exd4 25.Qh3 h6 26.Bxd4+ Qxc6 27.<Nf2>. The final move is losing, so I deleted the corresponding variation from my post. I have indicated edits in my post <[as follows]>. Saturday (Very Difficult): White to play and win.
Material: 2Ns + 2Ps for R+B. The Black Kh8 has 1 legal move. White has an advanced passed Pc6, backed by the 2 centralized Ns, Nd4 and Ne4. The Black Pe5 threatens Nd4, which can fork Qc7 and Rf8 at e6. The Black Qc7, the most valuable and therefore most vulnerable blockader, blockades Pc6, but can capture c6 if Nd4 moves. The White Qg2 is on the same diagonal as Pc6 and the Black Ra8. The White Rd1 has an open dfile, but can also move to the semiopen hfile. Only the White Ns are particularly active. The position suggests a largescale operation using the advanced Pc6 to distract the Black defense of the lightly defended Kh8. Candidates (24.): Rh1
24.Rh1 (threatening 25.Qh3 26.Qxh7#)
Black can accept the sacrifice of Nd4:
(1) 24…exd4 25.Qh3
In the face of the threat 26.Qxh7#, Black can reinforce existing defenses or flee: (1.1) 25…h6 26.Bxd4 (threatening 27.Qxh6+ 28.Qxg7#)
26…Qxc6 [Kg8 27.Qe6+ Rf7 28.g6] 27.Nf2
<[I deleted the remainder of this variation.]> (1.2) 25…Kg8 26.Qxh7+ Kf7
27.Qh5+ g6 [Kg8 28.g6 then 29.Qh8#] 28.Qh7+
The Black Kf7 has 2 flight squares.
(1.2.1) 28…Ke6 29.Qxg6+Kd5 [else, lose too much material at f6] 30.Rd1 (threatening 31.Rxd4#)
Black loses material to avoid mate.
(1.2.2) 28…Ke8 29.Qxg6+ Kd8 [Rf7 30.Rh8+ Bf8 31.Nd6+] 30.Bxd4 (threatening 31.Rd1)
White has 4Ps for a R and a huge mating attack against a completely disorganized army with an open Kd8. Black can refuse the sacrifice of Nd4, but only one defensive move alters the course of the attack favorably. (2) 24…g6 25.Ne6 Qxc6
[else, lose the exchange without compensation]
26.Rxh7+ Kxh7 27.Nf6+
<[Here, the computer points out that 26.Nf6 is stronger.]> Note that Ne6 prevents a lateral defense of Qc6 with …Rxf6. White wins R+N for Q, leaving him with Q+N+2Ps for 2Rs+B, and the Black Kh8 is in the open for checks. 

Aug0208   johnlspouge: I give the usual computer analysis, with <the last move entered by a human> and with complete computer variations, although humans can improve near the end. This position looks like a computer killer, so a more thorough computer analysis is desirable (but not feasible for me). Toga II 1.3.1 agrees with the game continuation:
[ply 15/63+ time 06:09 value +4.73]
24.Rh1 exd4 25.g6 h6 26.Bxd4 Kg8 27.Rxh6 gxh6 28.Qh3 Bf6 29.Bxf6 Rxf6 30.Nxf6+ Kg7 31.Qe6 Qa7 32.Nh5+ Kh8 33.Qe5+ Kg8 34.Kb1 Rc8 35.Qd5+ Kh8 36.g7+ Kh7 37.Qf5+ Kg8 38.Qg6 Rf8 39.gxf8Q+ Kxf8 40.Qf5+ Kg8 41.Qxa5 Toga II 1.3.1 also gives as the best play after my 25.Qh3 [ply 15/57 time 00:56 value +0.90]
24.Rh1 exd4 25.<Qh3> h6 26.gxh6 g6 27.Bxd4+ Kh7 28.Qe6 Rae8 29.Bf6 Bxf6 30.Nxf6+ Rxf6 31.Qxf6 Bc8 32.Rd1 Qe7 33.Qg5 Qc7 34.Qc5 Re6 35.Kb1 Rxc6 although the value for White decreases with increasing depth after 13 plies. Instead of 26.gxh6, I went for 26.Bxd4, which looks alright at 15 plies: [ply 15/63 time 05:11 value +1.33]
24.Rh1 exd4 25.Qh3 h6 26.<Bxd4+> Qxc6 27.Nd6 Bxg5 28.fxg5 Qxh1+ 29.Qxh1 Rf1+ 30.Qxf1 Bxf1 31.gxh6 Kh7 32.hxg7 Bh3 33.c4 bxc3 34.bxc3 a4 35.bxa4 Rxa4 36.Kd2 Ra6 37.Ne8 Bf1 38.Nc7 Ra2+ 39.Ke3 Bc4 40.Kf4 Ra1 41.Kg4 Kg8 Instead of 27.Nd6, I went for 27.Nf2, which is plain wrong, because White then has problems with mate threats: [ply 15/51 time 00:23 value 1.37]
24.Rh1 exd4 25.Qh3 h6 26.Bxd4+ Qxc6 27.<Nf2> Bxg5 28.fxg5 Qxh1+ 29.Qxh1 Rf1+ 30.Qxf1 Bxf1 31.gxh6 Ra6 32.hxg7+ Kg8 Re6 Be2 34.Kd2 Bf3 35.g4 Re4 Re2+ 36.Kd3 Re6 37.Kc4 Bxg4 

Aug0208   RandomVisitor: <Dr.J><I'm stlll puzzled. First, why did Rybka prefer 24 Rh1 dxe4 25 Bxd4 over 25 g6 in your original post?>The first run was at 17ply  Rybka misses some sequences when it does not think long enough <And secondly, in your line 24Rh1 dxe4 25 g6 h6 26.Bxd4 Kg8 27.Rxh6 gxh6 28.Qh3 Bf6 (instead of "resigns ?!") 29.Qe6+ Kh8 30.Nxf6 Qg7 31.Qd6 what happens after 31 ... Qxg6?>32.Nd7+ is deadly. 

Aug0208   RandomVisitor: <21ply> Rybka2.3.2a 1. (4.31): 24.Rh1 h6 25.Nf3 Rf5 26.gxh6 Qxc6 27.hxg7+ Kxg7 28.Qh2 Qg6 29.g4 Rff8 30.f5 Rh8 2. (2.80): 24.g6 h6 25.Qh3 exd4 26.Bxd4 Bh4 27.Qxh4 Kg8 28.Nf6+ gxf6 29.Bxf6 Rae8 30.Bd4 Rd8 3. (2.80): 24.Qh3 exd4 25.g6 h6 26.Bxd4 Bh4 27.Qxh4 Kg8 28.Nf6+ gxf6 29.Bxf6 Rae8 30.Bd4 Rd8 

Aug0208   johnlspouge: This puzzle seems to be one of the deeper Saturdays. On analysis, 4 separate themes emerge: (1) the obvious hfile threat with Rh1 and Qh3; (2) the dark long diagonal threat after the recapture Bxd4, with particular emphasis on control of f6; (3) the backrank mate threats emerging from the move g6; and (4) prevention of counterplay along the light long diagonal a8h1 by holding onto Pc6. The 4th theme is why White should delay putting Qg2 at h3 for as long as possible, to keep Qc7 immobile and bottled up with the threat of my Variation (2) below. The puzzle strengthens my conviction that activation is the key to solving the difficult puzzles. Here, 24.Rh1 activates Rd1 and prepares to activate Qg2 at h3, while the sacrifice of Nd4 naturally activates Be3 on the dark long diagonal. I missed 25.g6  but Ps can be activated, too! 

Aug0208
  kevin86: It's funny how white sacrificed both rooks to pawns to open lines. In one case the hfile,in the second case,the long diagonal. Both lines end at the eventual mating square:h8 

Aug0208   Lightboxes: I quickly skimmed the posts and did not see an analysis of 25. Rxh7+ so I put down what I thought would have been a good move: The king attempts an escape.
24. Rh1, exd4
25. Rxh7+, Kg8
26. g6, Rf6
27. Rh8+, kxh8
28. Qh3+, Kg8
29. Qh7+, Kf8
30. Qh8#
Although, I couldn't quite see a mate in the foreseable future if the king takes the rook and moves out. 24. Rh1, exd4
25. Rxh7+, Kxh7
26. Qh3+, Kg6
27. .....


Aug0208   johnlspouge: <<Lightboxes> wrote: I quickly skimmed the posts and did not see an analysis of 25. Rxh7+ [snip] Although, I couldn't quite see a mate in the foreseable future if the king takes the rook and moves out. [snip]> Under my usual conditions (below), Toga II 1.3.1 gives [ply 15/55 time 02:09 value (to White) 2.66]
24.Rh1 exd4 25.<Rxh7> Kxh7 26.Qh3+ Kg6 27.Qe6+ Bf6 28.gxf6 gxf6 29.Bxd4 Bc8 30.f5+ Kh6 31.Qd5 Kg7 32.g4 Ra6 33.g5 Qf4+ 34.Kb1 Bxf5 35.Nxf6 Kg6 36.Qc5 Qf1+ 37.Ka2 Rb8 I also looked at 24.Rh1 exd4 25.<Rxh7>, but like Toga, decided it lost. My chessforum contains detailed instructions on downloading freeware to avoid posting speculation. 

Aug0208   Slurpeeman: This puzzle almost made me cry (( i didn't even see the possibility of Q+R mating duo on the open file. i was thinking of sacrificing one of the knights (or even two and then winning the Queen in the course of discovered attack) and only then attacking the Black King's fortress i thought about 24.Qh3, but with the idea of exchanging Queens after P X N, Qd7(double attack), Q x Q; P x Q otaining a passed pawn. is there an chance i could win with that? 

Aug0208   johnlspouge: <<Slurpeeman> wrote: [snip] i thought about 24.Qh3, but with the idea of exchanging Queens after P X N, Qd7(double attack), Q x Q; P x Q otaining a passed pawn. is there an chance i could win with that?> Hi, <Slurpeeman>. White has N+2Ps for R+2Bs at the end of 24.Qh3 exd4 25.Qd7 Qxd7 26.cxd7 dxe3
The daily puzzles have made me somewhat bloodthirsty, so in my present view, your variation shows a laudable disrespect for pure material gain. Unfortunately, White has sacrificed far too much for the passed Pd7. <This puzzle almost made me cry> Join the club. It was a very subtle and instructive Saturday puzzle. I take my hat off to <dzechiel> for pulling a winning line out of the soup. 

Aug0208   Slurpeeman: you're right, as always, johnlspouge. It's all CG's fault tho  after seeing so many flashy sacs (especially when already down in material) that turn out to be winning mad me too fond of positional play and disregard material gain a bit too much. Now i've got to learn to be more patient in my calculations =)) 

Aug0208   johnlspouge: <<Slurpeeman> wrote: you're right, <as always>, johnlspouge.> Uhh, <Slurpeeman>, could I introduce you to my kids sometime? ;>) 

Aug0208   Slurpeeman: =)) that's going to be pretty hard, as we live too far apart  I live in Ontario, Canada. )) btw, do your kids know how to play chess? 

Aug0208   johnlspouge: <<Slurpeeman> wrote: =)) that's going to be pretty hard, as we live too far apart  I live in Ontario, Canada. ))> In fact, I was in Ontario, Canada for a week ending just a week ago, specifically at a conference in Toronto July 1923 and visiting my sister in London July 2426. You never know. <btw, do your kids know how to play chess?> My older daughter (10) learned, but neither she nor my other daughter (8) have any interest in the game. They really are unlikely to take my word for <anything> nowadays...and good for them! If you want to converse more "privately", feel free to visit my chessforum :) 

Aug0208   DarthStapler: I did't get it 

Aug0208   456: Friday puzzle Aug0108 <36. ?> B Abramovic vs Damljanovic, 1995 

Aug0208   zenpharaohs: It would make more sense if Rybka 3 and it's fancy new analysis features was released on a day with a problem like this as opposed to this coming Monday, when the problem will be easy. This was a pretty nasty one. I still don't really understand this one. 

Aug1508
  patzer2: Here's my analysis with Fritz 8 and the Opening Explorer: <1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e6 6. Bc4 Be7> The more popular alternatives are 6...a3 as in Navara vs Svidler, 2008 (by transposition) and 6...Nc6 as in
S Novikov vs Dreev, 2007 (by transposition). <7. Be3 OO>
The mainline here is 7...Nc6, transposing back to the 6...Nc6 game mentioned above. <8. Bb3 Nc6 9. Qe2 a6 10. Rg1> This unusual opening move is a sound but inrequently played alternative. Most often played here is 10. 000 as in F Amonatov vs A Timofeev, 2007. <10...Qc7 11. g4 Nd7 12. g5 Nc5 13. Rg3 Nxb3 14. axb3 f5 15. Qc4!?> White prepares to sacrifice the exchange for positional advantge. This was apparently a prepared improvement over the 15. Ncb5?!
played in Hector vs Shirov, 1989. <15... d5!>
Not good for Black is 15... f4? 16. Nxe6 $1 Bxe6 17. Qxe6+ Kh8 18. Nd5! Qd8 19. Nxf4 Qe8 20. c3 Ne5 21. Nd5 Nc6 22. b4 Rc8 23. b3 Rb8
24. f3 .
<16. exd5!>
White can also play for advantage with 16. Nxd5! exd5 17. exd5 Kh8 18. f4 Bd6 19. dxc6 Bxf4 20. Bxf4 Qxf4 21. Ne2 Qe5 22. OOO Be6 23. Qf4 Qxe2 24. Re3 Qb5 25. Rxe6 bxc6 26. Re5 Qb8 27. Rf1 . <16... f4 17. dxc6 fxg3 18. hxg3 b5 19. Qe2 b4 20. Ne4 a5 21. f4 Ba6?> This concedes White a clear advantage. Better for Black (and maybe the last best chance to hold) is 21... e5 22. Qc4+ Kh8 23. Nb5 Qd8 24. fxe5 Ba6 . <22. Qg2 Kh8 23. OOO e5 24. Rh1!!> This surprise sacrifice offer of the Knight is the best of several winning possibilities (see <Random Visitor>'s Rybka analysis) and gives White a decisive advantage, but requires precise followup. <24...exd4>
Black can also try 24... Bc8, however White appears to gain a decisive advantage after 25. g4! h6 [25... exd4 26. Rxh7+ Kxh7 27. Qh3+ Kg8 28. g6 Bh4 29. Qxh4 Re8 30. Qh7+ Kf8 31.
Qh8+ Ke7 32. Qxg7+ Kd8 33. Qf6+ Qe7 (33... Re7 34. Bxd4 Bxg4 35. Qh8+ Re8 36. Bf6+ Qe7 37. Bxe7+ Kc7 38. Qe5+ Kb6 39. Qd4+ Kb5 40. Qd3+ Kb6 41. Bc5+ Kxc6 42. Qd6+ Kb7 43. Qb6+ Kc8 44. Nd6+ Kd7 45. Qb7+ Ke6 46. Qf7#) 34. Qxd4+ Kc7 35.
Qb6#]
26. Nf5! Rf7 (26... Rxf5 27. gxf5 Bxf5 28. Ng3 Bh7 29. gxh6 g5 30. Qd5
gxf4 31. Bxf4 Bf6 32. Nh5 Bg8 33. Qg2 exf4 34. Nxf6 Qe7 35. Qg5 Bd5 36. h7 Qg7
37. Qxd5 Qxf6 38. c7 Rf8 39. Qd7 f3 40. c8=Q Qg5+ 41. Kb1 Qg7 42. Qxf8+ Qxf8
43. Qd4+ Qg7 44. Qd8+ Qg8 45. hxg8=Q#) 27. fxe5 Bxf5 28. gxf5 Rxf5 29. gxh6 g5
30. Bd4 Rd8 31. Nd6 Rf4 32. Qd5 Kh7 33. Be3 Rxd6 34. exd6 Qxd6 35. Qxd6 Bxd6
36. Bxf4 Bxf4+ 37. Kd1 Bb8 38. c3 Bd6 39. Ke2 g4 40. cxb4 axb4 41. Kd3 g3 42.
Rh4 g2 43. Rg4 g1=Q 44. Rxg1 Kxh6 45. Kc4 Kh5 46. Rd1 Bb8 47. Rd7 . <25. g6 h6 26. Bxd4 Kg8 27. Rxh6 gxh6 28. Qh3> 10. Black resigns in lieu of such possibilities as 28...Bf6 29. Qe6+ Kh8 30. Nxf6 Qg7 (30... Rxf6 31. Qxf6+ Qg7 32. Qxg7#; 30... h5 31. Nd7+ Qe5 32. Bxe5+ Rf6 33. Bxf6#)
31. Qd6 Rfd8 (31... Qxg6 32. Nd7+ Kh7 33. Nxf8+ Rxf8 34. Qxf8 Qg8 35. Qe7+ Kg6 36. g4 Bc8 37. Qf6+ Kh7 38. g5 hxg5 39. fxg5 Qg6 40. Qh8#) 32. Nd7 Rg8 (32... Qxd4 33. Qxd4+ Kg8
34. Qd5+ Kh8 35. Qf7 Rxd7 36. g7+ Kh7 37. g8=Q#) 33. Qe7! Rae8 34. Bxg7+ Rxg7 35. Qxe8+ Rg8 36. Qe5+ Rg7 37. Qf6 h5 38. Qf8+ Rg8 39. Qh6#. 


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