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|May-30-09|| ||Smothered Mate: 86. Bh7 with mate in 17
Next best in Be6 with mate in 23
|May-30-09|| ||BraveUlysses: Wow, this just baffled me and I couldn't nut it out. I was dimly aware of various points like the potential discovery check and the black K's potential corner entrapment, but I cannot even begin to calculate how this was forced. I would seem if black just keeps his N on c3 and moves the B along the a1-h8 diagonal, and keeps his K on a1 or b2 white isn't going to be able to mate him... yet somehow Nikolic has squeezed a win out of this drawish-looking position -against Korchnoi no less. Did Viktor make a mistake...?|
|May-30-09|| ||An Englishman: Good Evening: Partial credit. The first move was easy, but Black has 8 or more plausible defenses, and the complexities of this "simple" endgame were a bit much for me.|
|May-30-09|| ||totololo: Let's see
Th efinal position should be related to the black pieces as follows Kb3,Bh7, R on column A with the killing attack and the white K on a1.
So 1. Bh7 is obvious to put in place the battery Bh7 +Rc2
A1. 1. .... Bg7
2. Kc4 Na4
3. Kb3 Nb6
(Nc5 is countered by Rxc5+)
followed by the battery fire and RxN
so the knight should move .
However if the knight is given in c3 then echo positions occur as in the following variations:
A2. 1. Bh7 Bg7
2. Kc4 Bf6
3. Kb3 Bg7
4. Rxc3+ Ka1
A3. 1. Bh7 Bg7
2. Kc4 Na2 ( see A1 for Na4)
A31. 3. ... Nc3 see A2
A32. 3. ... Nb4 and now
A321 4. Rc4+ Nd3
5. Bxd3+ Ka1
A322 4. Rc4+ Ka1
The conclusion of the A solutions is that the Knight should move first !
Now there are 4 possible moves: in a2,a4,b5,d5
B1. 1. Bh7 Nb5 (with the threat of forking in a3 if Kc4 as in A variations ) So
2. Rc8 Be5 ( to protect b8)
3. Rc5 and one of the black minor pieces is lost so white win
B2. 1. Bh7 Nd5
2. Kd2 ( opposition to the knight ) followed by the battery fire winning one minor pieces
B3. 1. Bh7 Na4
2. Kd2 Nb2 ( any other B or N move the battery fires and one minor piece is lost)
3. Rc3+ Ka2 (Ka1 then 4.Ra3#)
4. Bg8+ Ka1
B4. 1. Bh7 Na2
2. Kd2 ( opposition to the knight) .... Ka1 ( if B or N moves then the battery fires
3. Rc8 B on the diagonal
4. Kc2 Nc3
5. Kb3 Na2
6. Ra8 B move
if 4. ... Nb4
5. Kb3 and rook in c8 threats are in c1# or in a8# and can't be covered both so # on move 6.
I enjoyed the puzzle for the artistic content. There is more counterplay on forking with the black Knight on B1-B3 variation that give value to the puzzle. That forking variations make the white king moves critical and require opposition ( rank, column or diagonal)...I appologize if I missed something.
Congratulation for the puzzle choice.
|May-30-09|| ||dzechiel: White to play (86?). White is up an exchange. "Very Difficult."|
This is one of those positions where you don't need the text "Very Difficult" to know it will be very difficult.
I'm just going to take a stab here, then check and see how it actually ended. My plan is to take advantage of the light squares. The black bishop only controls dark squares, and the black knight is on a dark square, which means when it moves, it can only check another dark square. I would like to reposition my king to b3, but I don't want to move the rook, as that would give the black king unearned freedom. So I would start...
Indirectly protecting the rook. Now black has lots of moves, but none that can stop my plan. Let's say he "passes":
86...Bg7 87 Kc4
Now there's a real threat, 88 Rxc3+. Black can't allow that.
87...Ka1 88 Kb3
and now black is lost. The threat is 89 Rc1+ Nb1 90 Rxb1#. If the knight moves, then it's 89 Ra2#. If the bishop plays 88...Bh6 then 89 Rxc3.
There must be better moves for black than 86...Bg7, perhaps
86...Nd1 87 Kd2
attacking the knight.
87...Nf2 88 Rc8+ and 89 Rxh8
I like this stuff. Time to check and see if we are close.
|May-30-09|| ||totololo: I wonder if 14... Nc7 followed by 15...d4 can't be a more effective way not to give the exchange. If someone has a chess program could you check, pls?|
|May-30-09|| ||Andrijadj: This one was not so hard...Bh7 is the most logical move,protecting the rook and not letting the king escape...|
|May-30-09|| ||dghins: Kd2 leads to mate in 12 moves.|
|May-30-09|| ||UnsoundHero: At first, I was wondering why black didn't play 51...Bxh4. Then I finally found 52 Rb8+ Ka6 53 b4 axb4 54 Ra1+ Na4 55 Bc4!|
|May-30-09|| ||OhioChessFan: Intuitively, I knew immediately Bh7 but there are way too many options for Black that I couldn't work out.|
|May-30-09|| ||tallinn: If you are looking for the perfect play of this position, try|
to gain access to the 6-piece Nalimov table bases.
|May-30-09|| ||newzild: I chose 86.Bh7 because it defends the rook. This means that white can play Kc4 and Kb3, with nasty threats. Black can't leave the king on b1 because of discovered check threats, winning a minor piece, so he must move it to a1. On this square, the king is susceptible to back-rank mate.|
I managed to figure this out in 20 to 30 seconds with a skinful of red wine, which suggests that this puzzle is too easy for a Saturday (and I missed one earlier this week without a skinful of red wine).
|May-30-09|| ||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
|May-30-09|| ||Geronimo: Anyone can see Bh7 as the best first move, as it frees the king to move toward the mating net square b3. But I didn't 'earn the point' today because I couldn't see black's best response ...Bg7, all the knight's options, etc... I guess this week's theme was "easy first move with many lines to calculate".|
BTW: Thank's for your clear analysis <totololo>. (And as always Dzechiel>!) I've tried to work into Dvoretsky's Endgame manual to varied degrees of success - as it's more suited to players stronger than I. Do you have any suggestions for a good education in engame theory that could lead towards Dvoretsky's master class?
|May-30-09|| ||ChessBookForum: <Geronimo> Try Jesus de la Villa's <101 Endgames You Must Know>. It will give you an easy-to-read firm basis from which to move forward.|
|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.
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