[blind-chess] Spoiler Alert Problem WAC071
- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Sun, 12 Jun 2011 20:25:56 +0100
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: Three pawn islands, and a pawn down. The 2 queenside pawns are each
isolated, and potentially more difficult to defend. However, here is a position
with opposite-wing castling. This means if black were to get greedy, and play
to capture these pawns, then white will have been given open lines down which
attacking pressure can be mounted. Assessing wether black is winning pawns, or
just opening up lines for a quick defeat, is not easy to judge. The 3 kingside
pawns are unmoved, and not under pressure. The king is not under immediate
threat from black, it will be several moves for black to get activity. The
queen is challenged by her black counterpart, but has many squares to which to
move, should this be deemed desirable. The b1 rook has moved to a semi-open
file, though the power of the rook is blocked for the moment by the b5 knight.
The f1 rook might have to stay where it is for a while, black may be able to
mount an attack on f2, involving a pawn d3 move at some point in the future,
though this is a few moves away. The bishop is excellently placed, firing down
an open diagonal straight into the castled king's locality. The knight is
aggressively placed, and may be able to combine with the f4 bishop should the
opportunity arise
.
Black: Three pawn islands, and a pawn up. The queenside pawns have yet to move,
and black should only consider moving either of them if it is absolutely
necessary. The d4 pawn is passed, and should black be able to neutralise the
white piece activity, and exchange down to an ending, then this pawn may be the
decisive factor. This plan, is of course, a very long way away. The kingside
pawns have yet to move. In opposite-wing castling, one way of mounting an
attack, is to hurl the pawns in front of the opposing king, down the board as
quickly as possible. Black is going to need much free time to play this plan,
and might find there is never going to be time for such a pawn charge. The king
is under considerable pressure. There are 4 white attacking units putting
pressure into the queenside. Not only that, it is the h2-b8 diagonal which is
seriously weak, that white f4 bishop is dramatically restricting the mobility
of the black king. The queen is pinned to her king, but if given the chance,
should definitely trade queens next move. The d8 rook is supporting the
potential game-winning d4 passed pawn, but will find difficulties to assist in
defending the king, since the dangerous white activity is from minor pieces.
The h8 rook is ready to centralise, and control the e-file. The c5 bishop is
defending , and will need several moves to re-locate itself in order to
neutralise the activity of the white bishop. The knight on f6 is neither
attacking nor defending
.
** Hints section, 6 hints
.
Hint 1, to find the key move
.
The white queen is going to be needed for any attack, so what should she do?
.
Hint 2, to find the key move
.
Examine any forcing moves, and look for any new weaknesses which might have
been created by their actions
.
Hint 3, to find the key move
.
If the white heavy pieces are to get into the action, then some lines need
opening
.
Hint 4, to find the key move
.
The crucial action will take place on dark squares
.
Hint 5, to find the key move
.
An English king, in the middle of a battle, is reputed to have said: "A horse,
a horse. My kingdom for a horse". He wanted to trade a kingdom for a horse,
right? So, does that mean the reverse trade is possible?
.
Final hint, to find the key move
.
They say, "Don't look a gift horse in the mouth". Ah, but what if it is not a
gift?
.
** Proposed solution to WAC071
.
The key factor in this position, is the powerful white bishop, restricting the
black king entirely. White would like some open lines over on the queenside, to
permit heavy piece infiltration. So, white starts with a forcing move, 1.
Nxa7+. Black has no choice, 1. ... Bxa7. Now, the white queen can switch from
the kingside to the queenside with, 2. Qa3. The queen could not have moved here
previously, the black bishop on c5 preventing this strong change of direction.
Black has a few moves to consider now
.
Variation A: 2. Qf5, which lets the bishop go, in order to create a flight
square on d7 for the king, and also attacks that annoying white bishop. White,
however, has too many trump cards here, 3. Qxa7, and if, 3. ... Qxf4, then
simply, 4. Qxb7+ is mate. Black will not comply and take the bishop, instead,
3. ... Kd7, trying to run away seems sensible, but it fails to, 4. Rxb7+, and
now the threats with white queen and rook along the 7th rank are tremendous. If
now, 4. ... Ke6, then simply, 5. Re7+ is mate. Instead black goes, 4. ... Ke8.
Now white has a forced mate in 4 as follows, 5. Re7+ Kf8 6. Rxf7+ Kg8 7. Rxg7+
Kf8 8. Qf7+ mate
.
Variation B: 2. ... Qg4, similar to variation A, but now the f5 square is free
for the black king. So, 3. Qxa7 Kd7, and white has such a powerful position,
there is time to prevent the black king from escaping with, 4. Rfe1. Now here
is a position with many choices for black. The obvious piece snatch with, 4.
... Qxf4 loses to, 5. Qxb7+ Kd6 6. Rb6+ mate. It seems black must instead try,
4. ... Rb8, but white wins with, 5. Rxb7+, and the trade of rooks is virtually
forced, 5. ... Rxb7 6. Qxb7+ Kd8 7. Qc7+ mate
.
Variation C: 2. ... Qc6, again freeing d7 for a flight square, and trying to
save the b7 pawn. White continues with, 3. Qxa7, and now there is material
equality, but white has a fantastic attack. Black could blunder with, 3. ...
Nd7, guarding the b8 square, but allowing, 4. Qa8+ Nb8 5. Qxb8+, and queens
will soon trade, and white is a piece up. Black will not bring the knight to
it's doom, instead, 3. ... Kd7, trying to run away to f5, but, 4. Rxb7+ Ke6.
Note if, 4. ... Ke8, it is a forced mate in 4, given above. Now, the black king
is on the 6th rank, so, 5. Rb6 skewers the black queen to the king
.
Variation D: 2. ... b6, or 2. b5, they are essentially the same, so just
assume, 2. ... b6 is the move. The queen is now guarding the a7 bishop, and the
b6 pawn is blocking the action of the white rook down the b-file. Remember,
heavy pieces enjoy open lines, so white can break through with, 3. Rxb6. If
black takes the bait with, 3. ... Bxb6, then simply, 4. Qa8+ mate. Instead,
black is advised to give the king a flight route, and the queen must keep guard
of the bishop, so, 3. ... Rde8 seems right, but now white invades with, 4.
Qa6+, the black reply is essentially forced, 4. ... Kd8. Now black loses the
queen with, 5. Rd6, and if that was not enough, the a7 bishop is still a
problem, and the king is still exposed
.
Variation E: Which I choose to regard as the main line of my proposed solution.
It is, 2. ... Bb8, escaping the attack from the white queen, and challenging
that powerful white bishop. It is not so simple as that for black, is it? Well,
3. Qa8, a strong infiltration to the black back rank, pinning the b8 bishop,
and also threatening to capture on b8 with checkmate. Again, the black king
needs a flight square, and it must be a queen move. This time the black queen
can not move to either f5 or g4, since white will play 4. Qxb7+ mate. So black
must play, 3. ... Qc6, and now white regains the material with interest with,
4. Qxb8+ Kd7 5. Rxb7+. The black king has 2 choices, if, 5. Ke6, then simply,
6. Qe5+ is mate. Instead the king goes, 5. ... Ke8, but now the last white
piece joins in with, 6. Re1+. Black can block the file with, 6. ... Ne4.
Instead, 6. ... Kf8 immediately loses the d8 rook, and much more will follow.
So, now the white queen springs into central action with, 7. Qe5+, and black
must lose at least a knight to 8. Qxe4, no matter what black does, and inferior
replies on move 7 for black can lose much more
.
** Condensed proposed solution
.
1. Nxa7+ Bxa7 2. Qa3 Bb8 3 Qa8 Qc6 4. Qxb8+ Kd7
5. Rxb7+ Ke8 6. Re1+ Ne4 7. Qe5+
.
** Other tactical variations considered, and rejected
.
Liquidating the tension with, 1. Qxd7+, is a very poor mis-judgement of the
possibilities in the position. White does not wish for an endgame, there are
well placed pieces, all ready to start tactics. There is however a chance for
black to go wrong. If, 1. ... Kxd7, anticipating an endgame, and getting the
king into the centre, there would follow, 2. Nxa7, regaining a pawn. If then,
2. ... Bxa7, then white regains the piece with, 3. Rxb7+, and also winning a
pawn. Instead, after 1. Qxd7+, simply, 1. ... Rxd7 and white has no immediate
threat, and the attack can be slowly pushed back
.
From the start, there is the very tempting, 1. ... Qa3, which sets a tricky
test for black. The obvious, 1. ... Bxa3, leaves white with a pretty end to the
game with, 2. Nxa7+ mate. Note how the white bishop leaves the black king
without a single legal move, and the knight gives check. So, what has black got
against, 1. Qa3 then? There is quite some complicated lines should black choose
from, 1. ... Bb6, or 1. ... b6. However, black has a startling counter in, 1.
... Qxb5, and white is helpless. The minor piece mating pattern has been
broken, the white queen is attacked, and black is a piece up. If either, 2.
cxb5 or 2. Rxb5, then, 2. ... Bxa3, a simple win for black. There is, 2. Qh3+,
escaping the attack from the bishop and giving check, and also leaving the
black queen in trouble. However, 2. ... Qd7, the black queen escapes and blocks
the check, and lack has won a piece
.
Lastly on move 1 for white, Any other queen move gains nothing. If there was a
quick way to reach the e5 square, then the queen supported by the bishop down
the h2-b8 diagonal would be crushing. No such forcing manoeuvre exists
.
** Alarm bells
.
1. The dark squares around the black king are controlled by white. Earlier
different play by black might have prevented this. This is a classic example of
massive positional compensation, for just one pawn
.
2. The forcing knight sacrifice on a7, opened up two files, the a-file, and the
b-file, for a decisive invasion by the white queen and rook, while the dark
squares around the black king were further weakened
.
3. Any king without a move, like the black king here, is very likely a prime
candidate for a decisive attack
.
4. Note very carefully the path taken by the white queen, once the white knight
had created a half-open a-file. Her journey, in the 7 move proposed solution,
saw her move from one side of the board to the other. Then an 8th rank
invasion. Next a material-gaining capture. Finally, a centralising check to win
a knight. That is what queen mobility is all about
.
Paul Benson.
-----Original Message-----
From: R Dinger - Email Address: rrdinger@xxxxxxxxxx
Sent On: 06/06/2011 19:02
Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx
Subject: [blind-chess] Problem WAC071
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.
Problem WAC071
White to move
FEN Problem Setup:
2kr3r/
pp1q1ppp/
5n2/
1Nb5/
2Pp1B2/
7Q/
P4PPP/
1R3RK1
w - - 0 1
Short Algebraic Problem Setup:
White: Kg1, Qh3, Rb1, Rf1, Bf4, Nb5, Pa2, Pc4, Pf2, Pg2, Ph2
Black: Kc8, Qd7, Rd8, Rh8, Bc5, Nf6, Pa7, Pb7, Pd4, Pf7, Pg7, Ph7
No virus found in this incoming message.
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07:35:00
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