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Aug2209
  kevin86: The pawn needed to be coaxed away from b6attack it enough and it will fall! 

Aug2209   remolino: Per the game, in my variation C, 19 Bxc6 Rxc6 20 Qb7 is immediately conclusive while 19. c4 is not. Black need not castle, could play Rg8 and although white has a much better position, there are no immediate material gains. 

Aug2209   obender71: Portisch got it much neater with Bxc6 BEFORE Qb7. It was so simple :((( And my analysis is flawed since after 19 ... Kd8 the move Nxd6 is not double check! For a reason I saw the Queen on the wrong diagonal. Epic fail. Again. 

Aug2209
  agb2002: White has the bishop pair for B+N. The compromising position of the black queen and the defenseless rook on h8 suggest the maneuver c5Bb5c4Bd2. 17.c5: A) 17... bxc5 18.Bb5 Qa5 (18... Rb8 19.Bxa4 Rxb2 20.Bxc6) 19.c4 Rg8 (19... 00 20.Bh6 and 21.Bxf8 or 20.Bxc6 Rxc6 (20... Bxd5 21.Bxd5) 21.Nxe7+) 20.Bxc6 Rxc6 21.Qb7 Bxd5 (21... Ne5 22.Qxe7#; 21... Ra6 22.Nc7+ or 22.Qa8+) 22.exd5 Ra6 (22... Rb6 23.Qc8#; 22... Rc7 23.Qa8+) 23.Qc8+ Qd8 24.Qxa6 + . B) 17... Nxc5 18.Bb5 Qa5 19.c4 Rg8 20.Bd2 Na4 21.Qc2 + . C) 17... Bxd5 18.c4
C.1) 18... 00 19.Bh6 f6 (or 19... Nf6) 20.cxd5 Nce5 21.Bxf8 Kxf8 22.c6 + . C.2) 18... Rg8 19.cxd5
C.2.a) 19... Nb4 20.a3 Nc2 (20... Na6 21.Bb5 Qa5 22.Bd2) 21.Bd1 + .
C.2.b) 19... Nb8 20.Bb5 Qa5 21.Bd2 + .
C.3) 18... Bxc4 19.Qxh8+ Nf8 20.Bxc4 Qxc4 21.Bh6 Kd7 22.Bxf8 + . D) 17... dxc5 18.Bb5 Qa5 19.c4, etc. 

Aug2209
  playground player: Reason # 549 Why I am Not a Grand Master: I just don't think big enough! Had I been playing this game, I would have moved Bh6 just to annoy Black and prevent him from castling. I would not have seen the opportunity for a major Queenside incursion. 

Aug2209
  johnlspouge: Saturday (Very Difficult)
Portisch vs A Deze, 1971 (17.?) White to play and win.
Material: B for N. The uncastled Black Ke8 has 2 legal moves. The Black Qa4 is loose and has 2 flight squares; the Black Rc8 and Rh8 are loose. The White Qb7 xrays Rh8 through c3, suggesting clearance. The Black Qside has weak light squares; the Kside, weak dark squares. Presently, both weaknesses appear incidental. The White Kg1 is secured from check. Candidates (17.): c5
17.c5, threatening
(A) 18.Bb5 Qa5 19.c4 then 20.Bd2 winning Qa5 or 20.Qxh8+ Black can accept the sacrifice of Pc5:
(1) 17…bxc5 [dxc5 permits the threat]
[17…Nxc5 18.Bb5 Qa5 19.c4 OO 20.Bd2 Na4 21.Qc1 wins Qa5] After 17…bxc5, d8 is a haven: Qa4a5d8.
Candidates (18.): Bb5, Qb7
18.Bb5 Qa5 [Rb8 19.Bxa4 Rxb2 20.Bxc6 wins N for P]
19.Bxc6 Rxc6 [else, drop N for P]
Candidates (19.): Qb7, c4
20.Qb7, threatening
(1.A) 21.Qxc6 or 21.Qa8+ [or 21.Qc8+] Qd8 22.Nc7+ Kf8 23.Qxd8 Any move by Rc6 permits the threats [e.g., 21.Qb7c8#]. Black must therefore protect Rc6. (1.1) 20…Bxd5 21.exd5 (threatening 22.dxc6 protecting Qb7) To avoid dropping Rc6, Black must move it.
21…Ra6 [else, permit the threat] 22.Qc8+ Qd8 23.Qxa6, winning Ra6 (1.2) 20…Qa6 21.Nc7+ Rxc7 [else, Nxa6] 22.Qxa6, winning Qa6 (2) Black can decline the sacrifice:
(2.1) 17…b5 [Bxd5 18.exd5 Nc6moves 19.c6 is a winning bind] 18.Bxb5 White wins a P, and the combination in Variation (1) then ensures the additional win of R for B at c5. (2.2) On 17…Nde5 [or Ndf6 or Nce5], White wins material with Threat (A), because Qb2 pins the moved N to the loose Rh8, and Pc3c4 still gains the required tempo. 

Aug2209   BOSTER: The mobility of Black Queen is too limited, she is almost trapped.
This is why17. c5 opening the green light for Bishop to b5,and the same time attacking b6 pawn .
17...bxc5to the center.
18.Bb5 Qa5 and then I had no any idea. 

Aug2209
  johnlspouge: < <Athamas> wrote: [snip] I can't believe this is what happens from the board, it looks so quiet and balanced, if a bit cramped from black. > I had exactly the same reaction to the position as <Athamas> and <TheBish>: the position permits a combination?!? I found it interesting that a methodical tactical analysis pointed so unerringly to 17.c5 as the only move worthy of any calculation. 

Aug2209   Eduardo Leon: Black's queen and rook are in a precarious situation. However, he could consolidate the position of the latter by castling. Therefore, white must take decisive steps against the queenside quickly. <17. c5!>
The main idea is that, after black takes the pawn with either the knight or the d pawn, the queen is trapped: <17. ... dxc5?/Nxc5? 18. Bb5 Qa5 19. c4> ... and <20. Bd2> comes next. Castling doesn't work either:
<17. ... 00? 18. Bb5 Qa5 19. Bxc6> ... winning a piece.
The most obvious defensive possibility is...
<17. ... bxc5>
... so the queen can return to d8 if white proceeds with the original plan (Bb5c4Bd2). But this fails as well: <18. Bxc6 Rxc6 19. Qb7> ... winning at least a piece:
<19. ... Ne5 20. f4> So the most stubborn line probably is...
<17. ... Qa5>
... but this only gives black more ways to die to choose from. White shall still play the key move: <18. Bb5>
Now <19. c4> is a serious threat. Besides transposing to the previous lines, black has other possibilities, all of which lead to disaster: <18. ... a6? 19. c4 Rg8 20. Bd2> ... or...
<18. ... Rg8 19. c4 bxc5> Now this is absolutely forced.
<20. Bxc6 Rxc6 21. Qb7> So the conclusion is <17. c5!> wins by force. 

Aug2209
  johnlspouge: < <remolino> wrote: [snip] 19 Bxc6 Rxc6 20 Qb7 is immediately conclusive while 19. c4 is not. > On Thursday, in Gligoric vs Sveshnikov, 1986, there was a similar tempting choice. In each case, diversion of the attack from the tactical theme was the inferior option. One could draw a moral: "Keep hitting your opponent relentlessly, where he is weakest." Hey, it's neither nice nor polite, but chess <is> a zerosum game :P 

Aug2209
  Jimfromprovidence: <Obit> <After your 17...Qa5, my first impulse was 18. cxb6. However, Bb5 seems to be good in all the main lines, so maybe just that: 17...Qa5 Bb5, threatening c4. Capturing the pawn transposes to the other lines, while 18. OO? allows 18...Bxc6.> <athamas> <I believe that line just basically transposes.
17. c5 Qa5 18. Bb5. You still can't castle because you lose a rook or knight.> Thanks for your comments. I don’t quite see the transposition, though. Here is the position after 17. c5 Qa5 18. Bb5 .
click for larger viewThe key difference here is that black has not played bxc5 in this position as in the text, leaving him with more options. To prevent 19 c4 he can play either 18…Ncd5 or 18…Nde5, for example. 18…f6 is another interesting possibility. For an offensive move, he can try 18…Nxc5?!
In summary, all of these lines seem incredibly difficult to follow. 

Aug2209   Eduardo Leon: <Jimfromprovidence>, after <17. c5! Qa5 18. Bb5> I fail to see how blocking the e5 square with either knight prevents <19. c4>. <18. ... Nce5 19. c6! Nxc6 20. c4> <18. ... Nde5 19. c4 bxc5 20. f4> The other possibility you mention can also be adequately refuted: <18. ... f6 19. cxd6 cxd6 20. c4> 

Aug2209   Athamas: The best try is probably as you suggest Jim, but it should still lose 17. c5 Qa5 18. Bb5 Nxc5 19. c4 Rg8
Now as Old Wolf pointed out earlier...
20. a3! and white has a queen.
20...a6 21. Bd2 Nd3 22. Qc2
The real key is black loses another tempo after moving to c4 because he cannot simply ignore the threat or castle away 

Aug2209   Athamas: And you lose 2 tempos if you move a knight to e5 after white pushes f4 

Aug2209
  Jimfromprovidence: <Eduardo Leon> <17. c5! Qa5 18. Bb5>
<I fail to see how blocking the e5 square with either knight prevents <19. c4>.
<18. ... Nce5 19. c6! Nxc6 20. c4>
<18. ... Nde5 19. c4 bxc5 20. f4>
The other possibility you mention can also be adequately refuted:
<18. ... f6 19. cxd6 cxd6 20. c4>> Your analysis is interesting.
My point was that there are plenty of options to work through in this 17 c5! Qa5 18. Bb5 line, knowing that black has better options than having to castle or play 18…a6 or 18…Rg8 in this continuation. In your first line for example, <18. ... Nce5 19. c6! Nxc6 20. c4> black does not have to play 19…Nxc6 but has 19…Nd5. If white follows with 20 c4 black has 20…a6 or 20…Bxd5. White has an advantage but it is a very deep position. 

Aug2209
  johnlspouge: < <JimFromProvidence> wrote: [snip] In summary, all these lines seem incredibly difficult to follow. > Because I try to "prove" the candidate puzzle move wins, I have developed methods to abbreviate my (longwinded and tedious) posts. The best method is to state the threat after (e.g.) White makes each of his moves. The analysis can then omit moves that do not meet the threat. By my convention, Black's later moves must all meet the threat. Today, some kibitzers repeat the threat of trapping Qa4 in several variations, making the lines "incredibly difficult to follow." Black can always play his responses to a threat one move early, but in my implicit conventions, if White just plays the corresponding move from the threat, the threat remains in force. My post considered responses to the candidate 17.c5 like Black's N moves, but they eventually transpose into the threat, or obviously lose material. The convention of stating the threat prunes the decision tree drastically, which speeds calculation in any situation where time is precious (such as over the board, or indeed, in life itself). 

Aug2209   WiseWizard: not only does it win material, the move is an excellent strategic decision because Black closes the c file and Whites's weak c pawn and file can breath a little. It also takes aggressive measure to avoid the nightmare of a knight on c4 where black would achieve a positional plus. Instructive play Portisch. 

Aug2209
  johnlspouge: < <Athamas> wrote: [snip] 17. c5 Qa5 18. Bb5 Nxc5 19. c4 Rg8 [snip] > The variation is essentially transposes the basic threat after the immediate response 17...Nxc5 (which I gave). Kotov's Rule (a P advantage terminates analysis) speeds calculation, particular if suboptimal variations are permitted. In several previous puzzles, suboptimal variations have followed a comprehensible human "logic" better than best play. (Today, e.g., I do not know if the variation I gave against 17...Nxc5 is best play.) 

Aug2209
  David2009: Saturday's puzzle Portisch vs A Deze, 1971 White to play 17? Very difficult There are no obvious forcing moves. I can play positionally to undouble my Pawns, e.g. 17 Bd4 Nxd4 18 cxd4 but White has no advantage. The Black Q is short of squares, so 17 c5 is possible. The Pawn can be captured in three ways: (a) If 17... bxc5 18 Bb5 Qa5 19 c4 Rg8 20 Bd2 and 20... Qd8 is forced. 17... bxc5 18 Bb5 Rb8 doesn't work: the Nc6 is en prise after the Queens come off. (b) 17... dxc5 is similar to line (a) but much worse for Black since the Queen is trapped. (c) 17... Nxc5 18 Bb5 Qa4 19 c4 Rg8 20 Bd2 traps the Queen. Conclusion: Black must play line (a). In exchange for the Pawn at c3 Black's pieces have been driven to very passive squares, and White can build up on the b file. Time to check. ========
I got the first two moves but not the stunning 19 Bxc6!! followed by
Qb7 winning everything. The unlucky Rook can't move anywhere sensible, neither can the Queen protect it. I wonder if Anton Deze was as surprised as I was when 19 Bxc6 was played instead of 19 c4. Time to digest other comments and the full game. 

Aug2209   wals: [Event "Vrsac"]
[Site "Vrsac"]
[Date "1971.??.??"]
[Round "?"]
[White "Lajos Portisch"]
[Black "Anton Deze"]
[Result "10"]
[ECO "A30"]
[Annotator "Rybka 3 1cpu (30m)"]
[PlyCount "39"]
{B37: Sicilian: Maroczy Bind
1. c4 c5 2. d4 g6 3. Nf3
cxd4 4. Nxd4 Nc6 5. e4 Nf6 6. Nc3 d6 7. Nc2 Bg7 8. Be2 Nd7 9. Be3 Bxc3+ 10.
bxc3 Qa5 11. Qd2 Nc5 12. f3 Qa4 13. OO Be6 ♗lack threatens to win material:
♗e6xc4 (13... OO 14. Nb4 ) 14. Nb4 (14. Rab1 OO (14... Qxa2 the
pawn must be left alone, otherwise ♗lack will be punished 15. Bxc5 Na5 16. Bd4
)) 14... Rc8 (14... OO 15. Nd5 ) 15. Nd5 (15. Bxc5 dxc5 16. Nd5 )
15... Nd7 (15... OO 16. h4 ) 16. Qb2 (16. Rab1 b6 17. c5 bxc5 18. Rb7
) 16... b6 ? ♙revents intrusion on c5 (16... f6 17. c5 (17. Qxb7
Rb8 18. Bd1 Qxc4 (18... Rxb7 19. Bxa4 Na5 20. Rfb1 )) 17...
Nxc5 18. Bxc5 dxc5 19. Qxb7 ) 17. c5 bxc5 ?? (17... Nxc5 18. Bb5
Qa5 ) 18. Bb5 Qa5 (18... Rb8 19. Bxa4 Rxb2 20. Bxc6 Bxd5 21. exd5 )
19. Bxc6 Rxc6 (19... Qd8 is not the saving move 20. Qb5 OO 21. Bh6 ) 20.
Qb7 (20. Qb7 f6 21. Qxc6 ) 10
The above may be of interest to those needing help. 

Aug2209
  David2009: After 17 c5! 17...Nxc5 is a very good try. Queen trapping is harder than it looks: <TheBish: [snip] D) 17...Nxc5 18. Bb5! Qa5 19. c4 f6 20. Bd2 Nd3 21. Qc2 Qa3 22. Rab1 Qc5+ 23. Be3 Qa3 24. Rb3 Qa5 25. Bd2! traps and wins the queen.>
Crafty plays 17...Nxc5 18 Bb5 Qa5 19 c4 Rf8 20 Bd2 Nd3 21 Qc2 Qa3 22 Rab1 Nc5! and if 23 Bb4 Qe6, or if 23 Rfe1 Kd8. <OBIT [snip] Simpler is 20. a3! trapping the queen without all the fuss.> Exactly. Continuing with <OBIT>'s suggestion gives 20 a3! Nd3 21 Qc2 Kd8 22 Qxd3 Ne5 23 Qe2 Bxd5 24 cxd5
and extricating the Queen has cost Crafty a piece.
http://www.chessvideos.tv/endgamet... 

Aug2209
  johnlspouge: < <David2009> wrote: <OBIT [snip] Simpler is 20. a3! trapping the queen without all the fuss.> Exactly. Continuing with <OBIT>'s suggestion gives 20 a3! Nd3 21 Qc2 Kd8 22 Qxd3 Ne5 23 Qe2 Bxd5 24 cxd5 and extricating the Queen has cost Crafty a piece. > Hi, <David2009>. Thanks. I missed 20...Nd3, so I underestimated 17...Nxc5. Your variation also indicates nicely how an "inferior" variation can be both simple and sufficient to win. 

Aug2209
  RandomVisitor: After 17.c5!
1: Lajos Portisch  Anton Deze, Vrsac 1971
click for larger viewAnalysis by Rybka 3 : (top 4 lines 20ply, the rest 19ply) 1. (2.86): 17...Nce5 18.Bb5 Qa5 19.c4 bxc5 20.Bd2 Qd8 21.f4 00 22.fxe5 Nxe5 23.Bh6 Rb8 24.Bxf8 Qxf8 25.Qa3 Qd8 26.Rab1 Rb7 27.Ba6 Rxb1 28.Rxb1 Bd7 29.Qb2 Kg7 30.Rf1 Bc6 31.Bb5 Bxd5 32.exd5 Qa5 2. (2.87): 17...Qa5 18.Bb5 Bxd5 19.c4 00 20.cxd5 Nce5 21.Bd2 Nc4 22.Bxa5 Nxb2 23.Bxd7 Rxc5 24.Bd2 Rd8 25.Bc6 Rc2 26.Bh6 f6 27.Rac1 Rxc1 28.Rxc1 Nd3 29.Rc3 Nc5 30.Ra3 a5 31.Be3 Rc8 32.Rc3 e5 3. (2.89): 17...Bxd5 18.Bb5 Qa5 19.c4 00 20.cxd5 Nce5 21.Bd2 Nc4 22.Bxa5 Nxb2 23.Bxd7 Rxc5 24.Bd2 Rd8 25.Bc6 Nd3 26.a4 Rc2 27.Be3 Rb8 28.Bb5 Nc5 4. (2.95): 17...a6 18.c4 f6 19.cxd6 Kf7 20.dxe7 Nxe7 21.Rac1 Rhe8 22.Bd4 Bxd5 23.cxd5 Rxc1 24.Rxc1 Rc8 25.Bf2 g5 26.Rxc8 Nxc8 27.Qc3 Nd6 28.Qc7 Ne8 29.Qa7 Nd6 30.Qxa6 Qxa6 31.Bxa6 b5 32.Be1 Nb8 5. (2.98): 17...Na5 18.cxd6 Bxd5 19.exd5 Nc4 20.Bxc4 Qxc4 21.dxe7 f6 22.d6 Qxc3 23.Qe2 Qc2 24.Qa6 Qc4 25.Qxa7 Qd3 26.Rfe1 Qxd6 27.Rad1 Qc7 28.Qa4 Qc6 29.Qb4 Qc3 30.Qh4 Qc6 31.Bf2 Kf7 32.Qf4 6. (2.99): 17...f6 18.Bb5 Qa5 19.c4 bxc5 20.Bxc6 Qd8 21.Qb7 Kf7 22.f4 Nb6 23.f5 Bd7 24.Nxb6 Bxc6 25.Qxc8 Qxc8 26.Nxc8 Rxc8 27.fxg6+ Kxg6 28.Rf4 Rb8 

Aug2209   WhiteRook48: missed it 

Aug2209   LIFE Master AJ: Saturday; August 22nd, 2009.
White to move, (17. '?').
click for larger viewPortisch vs A Deze, 1971 (Kostic Memorial in Vrsac, Yugoslavia.) First of all, you should read the posts of "all the usual suspects." (<dzechiel>, <thebish>, <once>, <agb2002>, etc. Also, <"RandomVisitor"> has a good RYBKA analysis of just about all the main lines here.) I consider it a waste of time to repeat most of what has already been stated. Secondly, I found this one easy ... at least compared to the madness of Beliavsky vs. Gulko. (Yesterday's puzzle.) Today, I was teaching my chess student (John Laning), so I printed out the diagram and we set it up on my chessboard. I saw ... almost instantly ... the possibility of the "clearance move" of 17.c4c5! I very quickly worked out one line ... NOT saying that these moves are the machine moves (or best), JUST WHAT I SAW OTB: 17...dxc5; 18.Bb5 Qa5; 19.c4 f6; '▢' (Much worse was: </= 19...00?; 20.Bxc6 Rxc6; 21.Nxe7#.) 20.Bd2 Nb4; 21.a3 Nd3; 22.Qc2 Nb4; 23.axb4, and White is winning the BQ, " " I quickly worked out a few other variations, including what was played in the game. BTW, my student gave the following line, claiming it was better for White. < 17.♕b3 ♘c5; 18.♗xc5 ♕xb3; 19.axb3 dxc5; 20.f4, " "> Turns out he was right! 


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