[blind-chess] Spoiler Alert Problem WAC090
- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Fri, 23 Dec 2011 00:37:36 -0000
Hello all,
This posting is divided into various parts. You can jump to the headings of the
sections by search/find for **, a pair of asterisks
.
** Positional evaluation of the problem
.
White: Two pawn islands. The 3 queenside pawns on dark squares, a3, b2, c3, are
not in any danger. The c4 pawn is attacked and undefended. The kingside pawns
have no weaknesses. The king is not in any danger, and though the f-pawn is
absent, there is no obvious way for black to exploit the slight exposure. While
the queen might appear to be passive on c1, she is putting some pressure onto
the dark squares in the black kingside. The rooks, on e1 and f1, have semi-open
files on which to work, and are ready to be lifted off the back rank, should
the option arise. The g3 bishop has considerable control of the dark squares,
since the black dark square bishop has been traded off. The knight on f5 has in
an active attacking location, placing pressure on the dark square pawns in
front of the black king
.
Black: Two pawn islands. The queenside pawn structure has been slightly
weakened by the doubling of pawns on the b-file. The kingside pawns on the dark
squares are under a little pressure. The king has defensive support from all
the black pieces. The queen is tied down to defending the c7 pawn, and could
find herself under attack at some point down the fully open d-file. The rooks
are not as well placed as the white rooks. The e8 rook has it's power
restricted by the e6 bishop, and the f8 rook is totally blocked in, and has
little immediate prospect of activity. The e6 bishop is attacking the
undefended white c4 pawn, and as white has no light square bishop, it can not
be easily challenged for light square control. The f6 knight is assisting in
defence of the king, but has no immediate prospect of advancing into the
centre, since there are no black pawns around to offer support
.
** Hints section, 5 hints
.
Hint 1, to find the key move
.
What does each side have, that the other does not? The difference will prove
decisive on move 3
.
Hint 2, to find the key move
.
According to legend, the Trojans showed little dental expertise
.
Hint 3, to find the key move
.
Oh, just the one gift, then? Try more generosity
.
Hint 4, to find the key move
.
Despite the queen being the strongest piece, this time the white queen is a
passive observer in the main line, though she will assist in some sidelines
.
Final hint, to find the key move
.
The black royalty are coming to a dark-squared defeat, in just 3 moves
.
** Proposed solution to WAC090
.
Despite having only 1 piece in the opponent's side of the board, white has a
dark squared destruction with, 1. Nxg7. This move has 3 effects. The black e8
rook is attacked, the black h6 pawn is now undefended, and can be captured if
permitted by the white queen on c1, and much more subtly, undermines the black
f6 knight. Oh, but surely that black f6 knight is protected by the black d8
queen, isn't it? Black has 2 replies
.
Variation A: Black declines to capture, and instead plays, 1. ... Re7. This has
saved the e8 rook, but now the f6 knight falls to, 2. Rxf6. Black, to avoid
being a piece down, must now capture the white knight with, 2. ... Kxg7, but
now white invades with, 3. Qxh6+, which leads to a forced mate in 2 moves as
follows: 3. ... Kg8 4. Qg5+ Kh8 5. Rh6+ mate. Note, how all the moves by white
took place on dark squares
.
Variation B: Black accepts the offered knight with, 1. Kxg7. White has 3
choices here, they all lead to wins
.
Choice 1: The proposed solution, and by far the most spectacular is, 2. Rxf6.
If black captures in either of 2 ways with, 2. ... Kxf6, then, 3. Bh4+, skewers
the black king and queen. Similarly, if black plays, 2. ... Qxf6, then another
bishop skewering of royalty happens with, 3. Be5, as the bishop is supported by
the white e1 rook. In each of these cases, black is losing a queen and pawn for
a white rook and bishop. This reduces the game to an ending, where white will
soon have a queen against black rook and bishop, since white is bound to lose
the c4 pawn almost immediately. This will be eventually won for white,the
critical factor is the state of the black pawn structure. The isolated kingside
pawns, and the doubled queenside pawns, will mean the white queen will just
keep shuffling around, slowly forcing the black army into defensive
contortions. Once the black pieces are tied down to defending,the white king
can advance to put further pressure around the black king. Soon, black will
lose a pawn on the kingside, and then the white kingside pawns will advance.
This sounds long-winded, but some endings need a little patience
.
So, with, 2. Rxf6, white is now doubly attacking the h6 pawn. The only defence
for the pawn is, 2. ... Rh8. White now plays, 3. Be5, which creates some
destructive discovered checks, so the black king must retreat with, 3. ... Kg8,
but unfortunately, this loses the h6 pawn. So, 4. Rxh6 Rxh6 5. Qxh6, and white
has threats of mate on g7 and h8. Black must play, 5. ... f6, but after, 6.
Bxf6, the mate on g7 is threatened again, and so is the black queen. Black must
play, 6. ... Qd7, but white finishes it with, 7. Qh8+ Kf7 8. Qg7+ mate
.
Choice 2: White, on move 2, refrains from capturing immediately on f6, instead
preferring to increase the pressure on the f6 knight. So, 2. Bh4, and black
must choose between allowing another queen for white rook and bishop trade, or
just let the knight go. The former, will produce a lost ending, that could
occur after say, the following forcing sequence, 2. ... Bxc4 3. Bxf6+ Qxf6 4.
Rxf6 Kxf6 5. Rxe8 Rxe8 6. Qf4+ Kg7 7. Qxc4, winning a bishop. The latter, that
is avoiding the black queen trade for white rook and bishop, gives white a
tremendous position. For example, 2. ... Qd7 3. Rxf6 4. Rh8, keeping guard of
the h6 pawn. Now, 4. Re5, intending to transfer to h5, and black will soon
crumble on the dark squares
.
Choice 3: White, on move 2, selects a different bishop pin with, 2. Be5. The
bishop now has some x-ray attack against the h8 square, so ideas of black, Rh8,
are prevented. If black chooses to avoid loss of queen for white rook and
bishop with, 2. Qd3, white can again advance the f1 rook with, 3. Rxf6, and
this time, 3. ... Rh8, attempting to defend the h6 pawn, loses material to, 4.
Rxh6+, discovered check. So, the h6 pawn can not be defended, and black must
now avoid ruinous discovered white rook checks with, 3. ... Kg8. Note, If
instead, 3. ... Kf8, then white plays, 4. Qxh6+, with gain of tempo for the
attack. So, now the black king is on g8 white plays, 4. Qxh6, which has the
sneaky threat of, 5. Qh8+ Kxh8 6. Rh6+, double discovered check, 6. ... Kg8 7.
Rh8+ mate. Black can only prevent this with, 4. Qh7, the point of black placing
the Queen on d3 earlier is revealed, but it is in vain. White concludes matters
with, 5. Qg5+ Kf8 6. Rh6 Qg8 7. Qxg8+, and if now, 7. ... Kxg8 8 Rh8+ is mate
.
** Condensed proposed solution
.
1. Nxg7 Kxg7 2. Rxf6 Rh8 3. Be5 Kg8 4. Rxh6 Rxh6
5. Qxh6 f6 6. Bxf6 Qd7 7. Qh8+ Kf7 8. Qg7+ mate
.
** Other tactical variations considered, and rejected
.
Any move other than, 1. Nxg7, just permits black to organise a defence
.
Option 1: White can again try to break through on the dark squares, but this
time with, 1. Nxh6+. This seems to achieve a winning game for white, but
because the complicated variations which arise are difficult to analyse
clearly, which gives white the option to mishandle the position, this move is
not given the status of being a proposed solution. Black has 3 replies. If
black tries either, 1. ... Kh7, or, 1. ... Kh8, white must retreat with, 2.
Nf5. Black, despite having just lost a pawn, should remove this dangerous white
knight with, 2. ... Bxf5. Simplifications will occur as pieces trade. White is
better, but not clearly winning
.
After white tries, 1. Nxh6+, the true test of this move must be for black to
accept the knight with, 1. ... gxh6. It might be tempting for white to grab
another pawn and also activate the queen with, 2. Qxh6, however, simply, 2. ...
Nh7, and white has no immediate follow up. It is still dangerous for black, but
careful regrouping, combined with challenging the white active pieces, should
slowly push white back. Instead of snatching the black h6 pawn, white should
continue to put more pressure onto the dark squares with, 2. Bh4, This now pins
an already attacked knight, white will regain the piece, but now the
complications emerge. Black plays, 2. ... Bxc4. This bishop capture attacks the
white f1 rook, and also opposes rooks down the now fully-open e-file. White has
to choose correctly from 5 moves. They are: 3. Qxh6, 3. Bxf6, 3. Rxf6, 3. Rxe8,
and 3. Rd1. As can be appreciated, these 5 white moves, will also generate a
variety of replies from black. Now, within 2 moves each from the start, this
looks like very hard work, the analysis tree is in danger of becoming a
Redwood. Here is one line which seems to win, there are likely to be more. So,
3. Rxe8, removing the possibility of the white queen being deflected from the
c1-h6 diagonal, should black trade rooks on e1. Black replies, 3. ... Rxe8, and
white regains the piece with, 4. Bxf6. Black must play actively with, 4. ...
Qd3, which has ideas of retreating to h7 if needed, and oh yes, black has also
threatened the white f1 rook, is all this black counterplay really worth a pawn
for white? As it happens, white has a neat reply here in, 5. Rf3, removing
itself from attack, and threatening to give check down the g-file, and while
the black queen is attacked as well. White now only has to take care of the
king with, pawn h3, at some point, before invading on the kingside dark squares
.
Option 2: From the start, perhaps white can try, 1. Bh4, which plans to
increase the dark square pressure, before playing for tactics on the black dark
square pawns. However, after, 1. Bh4, black might again choose to eliminate the
dangerous white knight with, 1. ... Bxf5. White will still have pressure on the
dark squares, but black may be able to hold matters. After, 2. Rxf5, black can
activate the blocked-in f8 rook with, 2. ... Rxe1+ 3. Qxe1 Re8. White can again
increase the pressure with, 4. Qf1, but black can defend with, 4. ... Re6.
White is now at a crossroads. Continuing to trade with, 5. Bxf6 Rxf6 6. Rxf6
gxf6, giving black the worse pawn structure, but with queens still on, white
will struggle to find a win. Instead, if white now does nothing, such as, 5.
b3, black is almost forced to put the question to white with, 5. ... g5, the
only way to break the pressure on the f6 knight, and the x-ray attack against
the black f7 pawn. White can not afford to sacrifice the bishop for the 2 black
kingside pawns, it is just to speculative, because the black queen and rook can
become active very quickly, long before the remaining white queen and rook can
attempt to infiltrate. After 6. Bg3 Qe7, black is uncomfortable, but not losing
.
Option 3: From the start, another tactical move for white is, 1. Rxe6. Well,
this type of move should be briefly examined. However, after black replies, 1.
... Rxe6, white has made no progress, and is just an exchange down for nothing
.
Option 4: From the start, Playing slowly with,, 1. b3, saving the c4 pawn,
allows black to eliminate the very dangerous white knight on f5 with, 1. ...
Bxf5. After, 2. Rxf5 Rxe1+ 3. Qxe1 Qd7, black has reduced the pressure against
the kingside
.
** Alarm bells
.
1. Here is an opposite colour bishop middle game. This offers opportunities for
attacks for both sides, on the squares which can not be defended with an
opposing bishop, because they are now spectators at the edge of the board
.
2. Only one white piece, the f5 knight, was actively posted. However, 4
long-range white pieces were skulking at a distance, ready to invade once the
position opened up. Safety can not be assumed, just because pieces are far
away, especially if those pieces have the capacity to move the length of an
open board
.
3. Once the combination was under way, and a pair of knights had been removed,
an opposite bishop middle game, with all heavy pieces arose. Since neither
bishop can challenge the other, then whichever side is attacking, is
effectively attacking with one more piece
.
4. The white knight, posted on f5, was able to expose the black king by
capturing the g7 pawn. This type of exposure is well-known. Defenders who leave
knights in such an attacking position, must calculate very carefully the
consequences of doing nothing about it
.
Paul Benson.
-----Original Message-----
From: R Dinger - Email Address: rrdinger@xxxxxxxxxx
Sent On: 12/12/2011 19:13
Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx
Subject: [blind-chess] Problem WAC090
Good Morning Puzzlers,
This problem is from Mario Lang's puzzle web page at
http://delysid.org/chess/epd.cgi
and is reported to be from Fred Reinfield's book "Win At Chess" 1958.
Note: This will be the last problem for the year.
Problem WAC090
White to move
FEN Problem Setup:
3qrrk1/
1pp2pp1/
1p2bn1p/
5N2/
2P5/
P1P3B1/
1P4PP/
2Q1RRK1
w - - 0 1
Short Algebraic Problem Setup:
White: Kg1, Qc1, Re1, Rf1, Bg3, Nf5, Pa3, Pb2, Pc3, Pc4, Pg2, Ph2
Black: Kg8, Qd8, Re8, Rf8, Be6, Nf6, Pb6, Pb7, Pc7, Pf7, Pg7, Ph6
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