[blind-chess] Spoiler Alert: Problem WAC102
- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Fri, 13 Sep 2013 17:56:14 +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 d4 pawn is isolated and can easily become a target
to the black heavy pieces. The kingside pawns are controlling some dark
squares, in particular g5, and as such will not inhibit the mobility of the
white d3 bishop. The king is rather short of piece protection, though black
will need a couple of moves before threats become serious. The queen is very
active on c8, probing at the black f8 knight and d6 pawn, though both are
protected. The rook on c7 is powerfully placed, controlling the 7th rank, and
combining with the d3 bishop to doubly attack the black h7 pawn. The d3 bishop
is pointing aggressively into the black kingside, in particular targeting the
black h7 pawn
.
Black: Three pawn islands. The b6 pawn is isolated which means it will need
protection from pieces. It is however, also a distant passed pawn, which in a
king and pawn ending will become a strong asset for black. The e6 and d6 pawns
are not easy targets for white. The h7 pawn is doubly attacked by white, but is
doubly defended by black, the knight and king offering defence. The king on h6
is very uncomfortable, having only 1 flight square. The queen is tied down on
d6, having to defend the b6 and e6 pawns, as well as the f8 knight. The rook is
actively placed on a1, but has no support from the black queen and knight, and
will not be able to create problems for white on its own. The knight on f8 is
tied down to defending the h7 pawn
.
** Hints section, 5 hints
.
Hint 1, to find the key move
.
But that is suicidal, isn't it?
.
Hint 2, to find the key move
.
Are we mining for gold here? No, we are undermining for gold actually
.
Hint 3, to find the key move
.
The biggest reward can sometimes demand the biggest investment
.
Hint 4, to find the key move
.
Piece values are inconsequential when the name of the game is forcing checkmate
.
Final hint, to find the key move
.
If this was soccer, the referee would book a large attacker for removing a
vital defender from the game
.
** Proposed solution to WAC102
.
It might appear that black is just holding the defence, but appearances can be
deceptive. The key to white winning is the restricted nature of the black king,
having only 1 legal move. This should start the search for a quick finish, and
captures with check are to be considered first
.
Option A: White lands a shocker on black with, 1. Qxf8+, which is giving away
the queen for a black knight. Surely this is bad house-keeping? No, the knight
was playing a vital defensive role, protecting the h7 pawn. If the knight was
not present at all, or located on the d5 square for example, then white would
be able to immediately play, 1. Rxh7+ mate. So, it is the f8 knight which
prevents the mate threat, and so if white can somehow remove that annoying
black knight, then mate on the h7 square is possible. This powerful queen
sacrifice should then emerge into the consciousness, as a means of undermining
the defence of the h7 pawn. The obvious black reply of, 1. ... Qxf8, needs
checking, and since the newly-located black queen on f8 does not protect the h7
pawn, then white has the makings of a mate in 2 moves. Simply, 1. Qxf8+ Qxf8 2.
Rxh7+ is mate. It is worth noting that the white queen sacrifice occurred with
check, making calculations of black's replies slightly easier, as the check
must be cancelled in some way
.
Black can try to spoil the fun by not accepting the queen sacrifice. After, 1.
Qxf8+, running away with, 1. ... Kh5, does not succeed. White can of course
play, 2. Qxd6, and be a queen and knight ahead, materialism is fine if there is
nothing better. However, white can still try to sacrifice the queen with, 2.
Qh6+. If black accepts with, 2. ... Kxh6, then, 3. Rxh7+ is mate. Black can
however further decline the white queen and keep running with, 2. ... Kg4, but
white finally ends matters with either, 3. Rg7+, or, 3. f3+, both of which are
mate. Note the importance of the white king on g2, preventing further fleeing
advances of the black king
.
Another set of mates in 3 moves are, 1. Qxf8+ Kh5 2. Rxh7+ Kg4, and now any of,
3. Qg8+, or, 3. Qg7+, or, 3. f3+, are all mate
.
Lastly, some more mates in 3 moves can occur after, 1. Qxf8+ Kh5 2. Qf7+, when
black can choose between, 2. ... Kh6 3. Qxh7+, or, 2. ... Kg4 3. f3+, both mate
.
It seems the white king on g2 is vital for some of the above mating patterns,
preventing the running black king from escaping on light squares f3 and h3, and
also being the necessary support to inflict the ultimate ignominy on the black
king, that is to give checkmate with a humble pawn
.
Tactics really do flow from a positionally superior game
.
** Condensed proposed solution
.
1. Qxf8+ Qxf8 2. Rxh7+ mate
.
** Other tactical variations considered, and rejected
.
Variation 1: White tries 1. Rxh7+, but after, 1. ... Nxf7, white can only
follow up with, 2. Qg8, which threatens both, 3. Qxh7+, and, 3. Qg6+, both
being mate. Black can easily prevent both threats with, 2. ... f5. White is not
quite finished as, 3. h5, again threatens Qg6+ mate. However after, 3. h5,
black can at least avoid mate with, 3. ... Kxh5, as, 4. Qxh7+ Kg5, note instead
4. ... Kg4 5. Qh4+ is mate, so after 4. ... Kg5 5. Qg7+ Kh5 6. Qh7+ Kg5, ending
in a 3-fold repetition. So, 1. Rxh7+ will not suffice for white. A draw for
black is not a failure, but to play for more needs careful analysis
.
If black is more ambitious, and after all analysing costs one nothing, then a
slightly riskier idea is after, 1. Rxh7+ Nxh7 2. Qg8 f5 3. h5 e5, the queen on
d6 is now guarding the g6 square. However, now white appears to obtains some
play with, 4. dxe5, and the black queen must stay on its 3rd rank with, 4. ...
Qc6+. White must block this with, 5. f3, since either, 5. Kh2, or, Kh3, allow,
5. ... Rh1+ mate. So after, 5. f3, black can achieve a materially won game by
finding, 5. ... Ra8, a not so obvious but vital retreat move which starts the
ejection of the white queen. After, 6. Qf7 Rf8, black has finally regrouped and
stopped all hopes of white finding a mate, black will win from here
.
Variation 2: White might try to increase the pressure against the h7 pawn with,
1. Qb7, which threatens mate in 2 with, 2. Rxh7+ Nxh7 3. Qh7+ mate. Black can
not stop this with, 1. ... Ng6, as, 2. Rh7+ is mate. Black can however prevent
mate with, 1. ... Qd5+, which forces a trade of queens. If white declines to
trade queens with, 2. Kh2, then disaster strikes with, 2. ... Rh1+ mate.
Instead, if the white king tries to run away with, 2. Kh3, then black has, 2.
... Rh1+ 3. Kg4 f5+ 4. Kf4 Qxd4+ 5. Be4 Qxe4+ 6. Qxe4 fxe4, leaving white a
piece down. So after, 1. ... Qd5+, White could block the check with, 2. f3, but
after, 2. ... Ra2+ 3. Kh3, black seems forced to trade queens with, 3. ...
Qxb7, and a rook and minor piece ending has arisen, where white is much more
active and has pawn targets to attack, but this will take both time and good
technique to win. So after, 1. Qb7 Qd5+, white should accept that queens are
going to be traded, and immediately play, 2. Qxd5 exd5, when black has 4
isolated pawns which will prove difficult to defend, white is much better but
no immediate mate will occur
.
Variation 3: White might try pawn-grabbing with, 1. Rc6. Black can either play,
1. ... Qd5+, creating problems shown above. White must block with, 2. f3, after
which black plays, 2. ... Qa2+, when white should restrict the black activity
with, 3. Rc2. The position is still better for white, but black can fight on
for some more moves. Instead, after, 1. Rc6, black can both attack and defend
with, 1. ... Qa3. White is still better as the black b6 pawn is difficult to
defend, and the black f8 knight must remain where it is to protect the e6 pawn.
White will keep black tied up for a long time, but is not guaranteed victory
.
** Alarm bells
.
1. The white bishop on d3 is powering into the black kingside. Such pieces
should be challenged early and neutralised before they become part of an
overwhelming attack
.
2. The white queen and rook might be appearing to be working vertically down
the c-file. They are instead actually operating horizontally along the 7th and
8th ranks
.
3. The restricted black king has only 1 legal move. This should be inspiration
to search for a winning combination
.
4. Lower value defending pieces are not immune to capture by a higher value
piece, piece values are always changing according to the position. A queen is a
highly valued piece, but can be sacrificed to achieve checkmate
.
5. The black king does not have any white pieces in his vicinity, and yet gets
mated. Long range pieces must not be underestimated, simply because they are a
long way away
.
6. The active black rook on a1 was part of an attempted attack. Perhaps a few
moves earlier, black should have diagnosed the danger of the 3 white long-range
pieces, and set the rook to work for the defence of his king
.
Paul Benson.
. -----Original Message-----
From: R Dinger - Email Address: rrdinger@xxxxxxxxxx
Sent On: 31/08/2013 00:37
Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx
Subject: [blind-chess] Problem WAC102
Good Afternoon Puzzlers,
Another WAC series problem.
This problem is from Mario Lang's puzzle web page at:
http://delysid.org/chess/epd.cgi
Problem WAC102
White to move
FEN Problem Setup:
2Q2n2/
2R4p/
1p1qpp1k/
8/
3P3P/
3B2P1/
5PK1/
r7
w - - 0 1
Short Algebraic Problem Setup:
White: Kg2, Qc8, Rc7, Bd3, Pd4, Pf2, Pg3, Ph4
Black: Kh6, Qd6, Ra1, Nf8, Pb6, Pe6, Pf6, Ph7
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