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|May-30-09|| ||randomsac: wow! this is a very intense endgame puzzle. I did guess Bh7, but I was unable to work through the rest.|
|May-30-09|| ||agb2002: White is an exchange ahead. Black pieces are loose or overburdened (defending themselves or preventing mate). This suggests 86.Bh7, threatening various discovered checks to win either the bishop or the knight:|
A) 86... Nd5 87.Rc8
A.1) 87... Bg7(f6-a1) 88.Kc4+ and 89.Kxd5 + -.
A.2) 87... Nb4+ 88.Kc4+ Nc2 89.Rxh8 + -.
A.3) 87... Nf4+ 88.Ke3+, etc.
B) 86... Nb5 87.Rc8 is similar to A.
C) 86... Na4 87.Kd2 (threatening 88.Rc8+ and 88.Rc4+)
C.1) 87... Bc3+ 88.Rxc3+ + -.
C.2) 87... Ka1 88.Rc8 followed by 89.Ra8 + -.
D) 86... Na2 87.Kd2 (threatening 88.Rc8+)
D.1) 87... Bg7(f6-c3) 88.Rc7(c6-c3)+ + -.
D.2) 87... Bb2 88.Rc1#.
D.3) 87... Ba1 88.Rc1+ Kb2 89.Rb1+ Ka3 90.Rxa1 + -.
D.4) 87... Ka1 88.Rc8
D.4.a) 88... Bc3+ 89.Kc2 Bd4(e5-g7) 90.Ra8 followed by 91.Bg8 + -.
D.4.b) 88... Bg7(f6-d4,b2) 89.Ra8 followed by Bg8 + -.
E) 86... Nd1 87.Kd2 Nb2(f2) 88.Rc8+ + -.
E) 86... Ka1 87.Kc4
E.1) 87... Na4 88.Kb3 Nc3 89.Rc1+ Nb1 90.Rxb1#.
E.2) 87... Na2 88.Kb3 + -.
E.3) 87... Bg7(f6,e5) 88.Kb3 + - (the knight is lost).
E.4) 87... Kb1 88.Rxc3+ + -.
F) 86... Bg7(f6,e5) 87.Kc4 (threatens 88.Rxc3+ and 88.Rg2(f2,e2)+) Ka1 88.Kb3 + - (the knight is lost).
|May-30-09|| ||johnlspouge: Saturday (Very Difficult)
P Nikolic vs Korchnoi, 1987 (86.?)
White to play and win.
Material: R+B vs. B+N endgame. The Black Kb1 has 1 legal move, a1. The Black Bh8 is loose and bears the burden of protecting Nc3. Being in a corner, Bh8 temporarily has only 1 diagonal. The White Kc3 is secured from checks.
If Black loses either Nc3 or Bh8 for nothing, he loses. To win, White must construct a mating net. The White Rc2 has Kb1 in a box. White should play his Kd3 to b3, while playing Bg8-h7 to protect Rc2 during the journey and incidentally threatening a discovered check along the b1-h7 diagonal to win a tempo.
Candidates (86.): Bh7
(White threatens 87.Kc4 88.Kb3, and then if …Ka1 89.Rc1+ 90.Rxb1#, else 89.Rc8+ 90.Rxh8 wins Bh8.)
(1) Flight is futile:
86…Ka1 87.Kc4 Na4 [else, 88.Kb3] 88.Kb4
White successfully shoulders Na4 away, so he can play 89.Kb3. Without 89…Na4-c5+, Black loses.
Only the Black Nc3 can frustrate the mate threat, and its squares are limited:
(2) 86…Na2 87.Kc4 Nc1 [else, 88.Kb3 wins]
88.Kb4 (threatening 89.Ka3 or 89.Rc8+ 90.Rxh8)
88…Bb2 89.Rc8+ Ka2 [Ka1 90.Ra8+ Na2 91.Kb3]
90.Ra8+ Ba3+ 91.Rxa3+ wins Ba3 and the game.
(3) 86…Na4 87.Kc4 (threatening 88.Kb4 89.Kb3 then mate)
87…Nb6+ [Nb2 Kb3] 88.Kb5 (threatening 89.Kxb6 or 89.Rc8+ 90.Rxh8)
Black must choose between losing B or N.
(4) 86… Nd5 [or Nb5] 87.Rc8 (threatening 88.Rxh8 or 88.Kc4+ 89.Kxb5)
87…Nf4+ [Nb4+ 88.Kc4] Ke4
Black must choose between losing B or N, because Bh7 prevents the double parry Nf4-g6 (which protects a threatened piece by moving a threatened piece).
(5) 86…Nd1 87.Kd2 (threatening 89.Kxd1 or 88.Rc8+ 89.Rxh8)
Black cannot parry all the threats.
|May-30-09|| ||agb2002: Curious. I overlooked 89.Kc2 in my line D.4.b after writing this move in the previous line. 89.Ra8 directly fails because of 89... Kb2, unpinning the knight.|
Initially I considered the possibility of forcing the exchange of the bishop for the knight because the black king is in the wrong corner (the same color as the bishop) but was unable to find a way to accomplish it.
|May-30-09|| ||WhiteRook48: didn't get it|
|May-30-09|| ||remolino: 86. Bh7 I think must be the move, with significant energy given discovered check threats with rook or king. Think I have worked the answer in most variations but not all.|
A. 86...Nb5, 87.Rc8 wins a piece
B. 86...Nd5, 87.Rc8 wins a piece
C. 86...Na4, 87.Kc4 and
C1.87...Nb6+, 88.Kb5 wins a piece
C2.87...Be4, 88.Kb4 wins a piece
C3.87...Nb2, Kb6 wins
D.86...Bg7, 87.Kc4 will win
Now, where I have not figure out all variations:
E. 86...Na2, 87.Rc8, Black can play 87...Ba1 or 87... Bb2. Intuition tells me White will win this position given cramped position of Black's pieces, but I have not got precise variations in all lines and have spent 30 minutes on this, so...
...Time to check.
|May-30-09|| ||remolino: OK, so in my line E. after 87...Na2, 88.Kd2 keeps Black tied up, while my 87...Rc8 allows the position to open up. So no point despite getting first move and all other variations right, because it would have been a draw all the same. Not enough to find Bh7 to get the point, you need to find a couple of other subtetlies.|
|May-30-09|| ||kevin86: A nice conclusion-now explain it to me...|
|May-30-09|| ||remolino: I will, someday...|
|May-30-09|| ||Jimfromprovidence: Black resigns because it’s forced mate in 7.
89…Nb4+ 90 Kb3 Na2 91 Rc2 Bb2 92 Rxb2 Nc1+ 93 Ka3 Nd3 94 Rc2 Kb1 95 Bxd3 Ka1 96 Ra2# or Rc1#.
(This is best play by both sides, courtesy of the Nalimov table bases, link below).
The table bases allow you to walk through any position to its conclusion. You can enter any legal move and the table base will calculate the result of the move (win, lose or draw) and the number of subsequent moves required to get there.
It’s a perfect resource for endgame learning.
As an aside, after 70 Rb8, white had a forced mate in 55 moves! Less than optimal play by black shortened that time frame.
|May-30-09|| ||zzzzzzzzzzzz: I got it... but I didn't get anything more than just the first move.|
|May-30-09|| ||zzzzzzzzzzzz: I got it... but I didn't get anything more than the first move.|
|May-30-09|| ||zzzzzzzzzzzz: Sorry, I wrote it twice|
|May-30-09|| ||tivrfoa: oh yeah! long game Oo|
|May-30-09|| ||dumbgai: Way too hard for me, I wasn't even close.|
|May-30-09|| ||Geronimo: Thank you <chessbookforum>. I just checked out your page and YOU ROCK!|
|May-30-09|| ||goodevans: Aha! My broadband link has finally been restored!
Got the first move OK, but there were just too many variations for me to calculate this late in the day.
|May-30-09|| ||njchess: Got this one, though it took some time. Bh7 enables the king to get to d2, and it forces the Black king into the corner for mate. Tough, well played game by both players.|
|May-30-09|| ||gofer: My thoughts were....
86 Bh7 ...
86 ... Nb5, Rc8 wins
86 ... Nd5, Rc8 wins
86 ... Nd1, Rc8 wins
86 ... Na2, 87 Kc4 Nc1, 88 Kb4 Na2, 89 Ka3 Nc1 90 Ra2#
86 ... Na4, 87 Kc4 Nb2/6, 88 Kb3 ..., 89 Ka3 ... mating
86 ... Bg7 (or Bf6 or Be5) , 87 Kc4 Bh8, 88 Kb3 Ka1 89 Rc1#
(okay these three are just an examples, not real theory, as I think Na2, Na4 or a Bishop move are not going to be blacks first choice I would recon that he will pay Ka1 immediately)
86 ... Ka1 (virtually forced)
87 Kc4 ...
88 Kb3 ...
89 Ka3 or Ra2# or Rc1#
all these moves are really unavoidable for black...
time to check...
|May-30-09|| ||gofer: Using the link provide by <Jimfromprovidence> (TVM), I now have a better understanding of why my simple Kc4, Kb3, Ka3 approach just doesn't work! But it does keep the discovered check in place and that means that a mate is only 10 more moves away...|
...hmmm not sure that I am completely happy about having a computer spell it all out for me in black and white...
...but it is nice to know how and why you went wrong!
|May-30-09|| ||CHESSTTCAMPS: In this endgame position, white can cash in on the mobility advantage that a rook has over the black minor pieces. white's |
rook is already in a strong position that limits the black king to 2 squares. Therefore,
..to set up a dangerous battery and free the white king to get closer. Now, if
A. 86....Bg7 (or f6 or e5) 87.Kc4 Ka1 (otherwise, a discovered check wins B or N) 88.Kb3 and black can only stop Rc1# by giving up the knight.
KNIGHT MOVES (in clockwise order):
B. 86...Na2 87.Kd2! (Kc4 Bb2 stops progress) Ka1 88.Rc8! Be4 (best, but B-any is met by Kc2) 89.Kc2 Nb4+ (there is no defense against Ra8) 90.Kb3 Na2 91.Ra8 Bh7 (trying for stalemate) 92.Bg6 B-any 93.Rxa2#
B.1 87...Bg7 (or f6 or e5 or d4) 88.Rc7+ (or Rc6+ or Rc5+ or Rc4+ wins the B)
B.2 87...Bf3+ 88.Rxf6+
B.3 87...Bb2 88.Rc1#
B.4 87...Ba1 88.Rc1+ Kb2 89.Rb1+ wins the N
C. 86...Na4 87.Kc4 Ka1 88.Kb3 Nc3 89.Rc1+ and mates next
C.1 87...Nb2 (or b6) 88.Kb3 Ka1 (otherwise, a discovered check wins B or N) 89.Rc1#
D. 86...Nb5 87.Rc8 B-any 88.Kc4+ wins the N
E. 86....Ne5 87.Rc8 B-any 88.Kc4+ wins the N
E.1 87...Nb4+ 87.Kc4+ wins the N
E.2 87...Nf4+ 88.Ke3+ wins the N
F. 86...Nd1 87.Ke2 Nb2 (or Bc3+ 88.Rxc3+) 88.Rc8+ wins the B
G. 86...Ka1 87.Kc4 Na4 (or Na2) 88.Kb3 wins
G.1 87...B-any 88.Kb3 wins
G.2 87...Kb8 88.Kb3 leaves no defense against Rxc3+ or other winning discovery.
All this analysis is presented as proof - not to scare chess students away from tricky endings. The main principles to remember are: (1) Maneuver the white king to get close to the black king and create mate threats, but be careful to avoid forks. (2) Look for chances to reposition pieces favorably by attacking a loose piece to gain a tempo. (3) In general, try to restrict the mobility of the opposing pieces. (4) when the opposing king is trapped, keep it that way!
|May-30-09|| ||CHESSTTCAMPS: <dzechiel> <...I like this stuff> |
<totololo:> <...Congratulation for the puzzle choice.>
<Craigokat: Bh7 is vaguely reminiscent of endings
with K+Q vs. K+R. Some of the key positions involve setting up discovered check by placing the Q behind the king on a diagonal>
I agree with the positive comments about this challenging puzzle. The last comment is particularly interesting, because I have fits with that ending.
|May-31-09|| ||totololo: <Geronimo>I prefer Averbach books on endings .... I think that now they are on CD.|
|Jun-01-09|| ||patzer2: Nikolic's 86. Bh7! solves the Saturday, May 30, 2009 puzzle with a clever endgame tactic which utilizes the dual threats of discovered check or mate (e.g. White Rook on c1 and White king on b3 or White Rook on a8 and White King on b3) to secure the win.|
See <CHESSTTCAMPS> post above for an excellent discussion of the ideas and plans as well as the specific tactics involved with this winning move.
|Jun-01-09|| ||patzer2: <CHESSTTCAMPS> <E. 86....Ne5 87.Rc8 B-any 88.Kc4+ wins the N> I think you meant 86...Nd5 87. Rc8! etc.|
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