[blind-chess] Spoiler Alert Problem WAC073
- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Sun, 26 Jun 2011 14:31:58 +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: Two pawn islands. The a-pawn has advanced, trying to claim some space,
and also provide an anchorage point for a knight on b5. It also combines with
the queen and c3 knight, to prevent black from attempting to open the queenside
with, pawn c6, and pawn b5. The kingside pawns can be considered as two units.
The g-pawn and h-pawn offer protection to the king, and the e-pawn and f-pawn,
have advanced as part of an attacking plan. They have become locked, but this
is not such a problem. There is enough space behind the white pawns for the
white pieces to manoeuvre. The king is safe, and there is almost no way for
black to create threats for a good while. The queen has considerable
flexibility. She does not have to assist in the defence in any way, nor is she
tied down to defending any individual unit. This offers her complete freedom to
create attacking threats as she chooses. The d1 rook is sitting on a fully open
central file, as good as can be expected in the early middle game, and also
puts pressure on the black d7 bishop. The h3 rook is aggressively located,
though can not break through on it's own. The c3 knight has influence on the
centre, with the opportunity of moving to d5 if thought necessary. The e6
knight has wandered up the board, and is a little precarious. It is doubly
attacked, and only once defended. It does however, have attacking possibilities
on the dark squares in the black kingside
.
Black: Two pawn islands. The a-pawn has advanced to block the advance of the
white a-pawn. The kingside pawns are all on dark squares. There is a hole on
g6, but it is not immediately obvious how white can exploit this. The king is
in some danger. he is in a corner, and his mobility is restricted by a rook and
pawn. Black has a dilemma which often confronts defenders. To safeguard the
king from being overpowered, pieces must be close by to neutralise the threats.
However, if they get too close, they can suffocate him. It all depends on
coordination and space, and black is lacking in both. The queen is combining
with the d7 bishop, to attack the advanced white e6 knight, and this combining
threatens to win a pawn. The a8 rook has yet to move, and could consider the a6
square, as a means of entry to the game, though it might be better for black to
find a way for this rook to challenge white's control of the d-file. The g8
rook is trying to defend the king, but had the choice been available earlier,
the f7 square may well have been a better location, permitting the king to run
along the back rank, should it be necessary to flee. The d7 bishop is part of a
threat to win a pawn on the e6 square. The e7 bishop is considerably restricted
by the kingside pawns
.
** Hints section, 5 hints
.
Hint 1, to find the key move
.
The cornered black king is vulnerable to a particular mating pattern, in would
you believe, just 3 moves
.
Hint 2, to find the key move
.
Not all combinations need to start with a bang, do they?
.
Hint 3, to find the key move
.
A quick look in the diary, and oh yes, his Majesty has an
appointment/disappointment, with a femme fatale
.
Hint 4, to find the key move
.
The mating combination can not happen by force, it is just one of two
unstoppable threats
.
Final hint, to find the key move
.
Here is a short move, which creates a twin set of double attacks
.
** Proposed solution to WAC073
.
White has to take into account the double attack on the e6 knight. If it was
black to move, then simply capturing the knight, and then winning a pawn, looks
perfectly playable for black. White would find difficulties in creating threats
against the black king, and must find some way to avoid heavy piece exchanges,
leading to an endgame a pawn down
.
White can ignore the threat to the knight, because there is an opportunity to
create a double-threat. The first threat is to doubly attack a once-defended
piece, but much more dangerous for black, is the second threat of a
corner-square mating pattern. This happens with, 1. Qd2. A double attack
against the d7 bishop, but the h6 pawn is also a target. Black has little
choice here, any move which permits white to capture the d7 bishop is futile.
The d7 bishop can not be protected directly, if, 1. ... Rd8, then, 2. Nxd8, and
the d7 bishop still hangs. Black can play, 1. ... Bxe6, and now comes the point
of the second threat. White has, 2. Rxh6+, a forcing capture with check, and
the constricted black king is move-less, so, 2. gxh6 3. Qxh6+ mate. The
cornered black king is hemmed-in by the g8 rook
.There is another defensive try after, 1. Qd2. Black can block the d-file with
1. ... Bd6, but this allows white the luxury of 2 different finishes. There is
still the same, 2. Rxh6+ mating attack. However, white with a knight still
firmly planted on e6, has the much more spectacular, 2. Qxh6+. Again black must
capture, 2. ... gxh6+, and now a different mating pattern emerges with, 3.
Rxh6+ mate. Again, the g8 rook is restricting the black king, but here the e6
knight is preventing the g7 square from being an escape-door
.
** Condensed proposed solution
.
1. Qd2 Bxe6 2. Rxh6+ gxh6 3. Qxh6+ mate
.
** Other tactical variations considered, and rejected
.
Attempting to create the same dark square mating net with, 1. Qe3, will not
lead to checkmate. Black has a variety of ways of breaking the mating pattern.
Obviously, black will avoid, 1. ... Bxe6, which allows the proposed solution
above. The queen on e3 does not place a double attack on the d7 bishop, so this
piece does not have to do anything. Black can try, 1. ... Bf8, and now the h6
pawn is doubly defended. This can be removed with, 2. Nxf8, which again sets up
the mate threat on h6. Black has 2 recaptures on f8, if, 2. ... Qxf8, the d7
bishop is unprotected and falls with, 3. Rxd7. Instead, 2. ... Rxf8, avoids
immediate disaster and gives the king some breathing room, but will lose at
least a pawn, and possibly more, to, 3. Rxh6+. Black should just accept the
loss of the pawn, and suffer pressure against the king with, 3. ... Kg8, when
white is very much better, but must still find the path to victory. Instead,
after 3. Rxh6+, acceptance of the rook, 3. ... gxh6, loses to, 4. Qxh6+ Kg8.
Now the f8 rook is going to restrict the black king, as white continues to push
the black king back to the corner with, 5. Qg6+ Kh8. Now all white needs is a
rook check on the h-file, this pattern is more often observed with attacking
queen and rook combining on the enemy 7th and 8th ranks. So, 6. Rd3, and black
can only prevent an immediate checkmate by giving up a bishop and queen with,
6. ... Bxf5 7. exf5 Qxf5 8. Qxf5, black has avoided checkmate, but lost too
much material to survive
.
Again, if, 1. Qe3, black could try to prevent the tactics on h6 with, 1. ...
Kh7. This is rather risky. White has 3 attacking units pointing at the black
king, so something like, 2. Nxg7, has to be considered. Now the h6 pawn is
seriously weak, so black must take the knight, and white will have pressure for
some moves, but a checkmate is not obvious. There are some perpetual checks,
which can occur after, 2. ... Rxg7 3. Qxh6+ Kg8 4. Qh8+ Kf7 5. Qh5+ Kg8. Note,
if black wishes to play for more, then, 5. ... Kf8, leaves the possibility of
a rook retreat to g8. White will have much activity, and may find doubling
rooks down the d-file may keep the attack going, but it is not obvious that
white is winning
.
White could try inverting the move order of the proposed solution with, 1.
Rxh6+. The idea is to create a weakness on h6 before creating a double-threat.
The reply is forced, 1. gxh6, and now the queen has 2 choices. If, 2. Qh5,
threatening mate on h6 again, but now black has many options, and 2. ... Kh7,
seems to leave white without any immediate follow-up. Black can push out the
white queen with, Qe8, next move. So, after black has taken the h6 rook, it
must be, 2. Qd2, again a double-threat against d7 and h6. Black has no way of
saving the d7 bishop, and preventing the h6 mate, but remember, white has given
up a rook to reach this position, so black can afford to let some material go,
and it will have to be the d7 bishop. The simplest is, 2. ... Bf8, and white
should go for an ending with, 3. Qxd7. The activity of the white pieces might
just be enough to draw with accurate play, not what white really wants, is it?
.
Lastly, white could have just ignored any tactical ideas, and defended the
attacked knight with, 1. Qc4, which also threatens the black c7 pawn. White can
achieve a lot of pressure should black play, 1. ... Bxe6, For example, keeping
queens on seems sensible so, 2. fxe6, and the d7 square looks inviting for a
white rook. So, black can stop this with, 2. ... Bd6. Now black intends to
play, Re8 when appropriate, and just take the e6 pawn. White must play actively
with, 3. Nb5, which threatens to win a pawn on d6. So, 3. ... Ra6, defending,
but now white can increase the pressure with, 4. Rhd3. Black has no time to
round up the e6 pawn now, and so must defend again with, 4. ... Rd8. This is
good for white, there is, 5. Nxd6, and black is going to lose at least one pawn
after, 5. ... cxd6 6. Qxc8 Rxc8 7. Rxd6. Of course, after 1 Qc4, black does not
have to capture the e6 knight, but can instead play, 1. ... Bc6. White is
better, but has no obvious plan other than doubling rooks on the d-file, which
will keep pressure, but this is not decisive
.
** Alarm bells
.
1. Black had two weaknesses. The primary weakness, was the potential mating
pattern against a cornered and restricted king, though this alone, can not be
exploited by force. White will have been aware of the potential mating pattern,
when placing a rook on h3,
.
2. The secondary black weakness, was the d7 bishop. Though it was not
restricted in movement, it was vulnerable to a double attack, and that double
attack was also one threat of a double-threat
.
3. A variety of middle game mating patterns should be committed to memory. This
will assist in planning, as the possibility can be recognised early. Then it is
a question of organising the pieces in such a way to create the possibility. If
a defending opponent, has not noted the danger, then a decisive attack can occur
.
Paul Benson.
-----Original Message-----
From: R Dinger - Email Address: rrdinger@xxxxxxxxxx
Sent On: 22/06/2011 03:40
Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx
Subject: [blind-chess] Problem WAC073
Good Evening 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 WAC073
White to move
FEN Problem Setup:
r1q3rk/
1ppbb1p1/
4Np1p/
p3pP2/
P3P3/
2N4R/
1PP1Q1PP/
3R2K1
w - - 0 1
Short Algebraic Problem Setup:
White: Kg1, Qe2, Rd1, Rh3, Nc3, Ne6, Pa4, Pb2, Pc2, Pe4, Pf5, Pg2, Ph2
Black: Kh8, Qc8, Ra8, Rg8, Bd7, Be7, Pa5, Pb7, Pc7, Pe5, Pf6, Pg7, Ph6
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