[blind-chess] Spoiler Alert: Problem WAC101
- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Tue, 30 Jul 2013 11:03:17 +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 queenside island has a passed c-pawn, which can
not make progress at the moment. The b-pawn is backward, and as such a
potential target for attack by the black rook, either from the f3 square or the
b8 square. The king on h1 has been hiding from whatever middlegame tactics have
preceded this position. The rook on e1 is attacking the black e4 pawn, but is
also tied down to defending the f1 knight. The knight on f1 could be regarded
as defending the kingside pawns, but this passive location for a short range
piece means the knight is not well placed
.
Black: Three pawn islands. The a7 pawn is isolated, and potentially vulnerable
to attack from the white rook down the a-file, though at present it is
protected by the d4 bishop, which also guards the a1 square. The e4 pawn is
both passed, a plus attribute, and isolated, a minus attribute. Which factor is
the greater depends on the remaining black forces, and how they interact with
each other. The king is safe and ready to centralise, possibly either thinking
of heading for the white queenside pawns, or supporting the e4 pawn. The rook
on f8 controls the fully open f-file, and also attacking the white f1 knight,
which in turn means the white rook must remain on the white back rank for the
present. The d4 bishop is centrally placed, and since white has no similar dark
square bishop, will be able to look forward to good prospects in the next few
moves
.
** Hints section, 5 hints
.
Hint 1, to find the key move
.
Passed pawns must be pushed, but remember, patience is a virtue
.
Hint 2, to find the key move
.
If the first move is a gentle nudge to the nose, the second move is a
jaw-cruncher
.
Hint 3, to find the key move
.
Don't you just love stories where the humblest of all becomes the eventual hero?
.
Hint 4, to find the key move
.
In Medieval days over here, when times were hard, the menu often offered a
second course of rook pie
.
Final hint, to find the key move
.
Opening strategy recommends: Knights before bishops. No-one seems to have
recommended: Endgame strategy: Bishops before rooks
.
** Proposed solution to WAC101
.
Black is going to be a piece ahead in just 5 or 6 moves, depending on how white
plays. The 3 active units are about to demonstrate the concept of coordination,
and in turn demonstrate how poorly coordinated the white forces are. Black
begins by taking control of the promotion square for the e-pawn with, 1. ...
Bc3. The white rook is tied down to the back rank, since if, 2. Rxe4 Rxf1+,
black wins a piece. So, the rook moves sideways and the best is probably, 2.
Rc1, attacking the unprotected black bishop. Now black produces the winning
concept with, 2. ... Rxf1+. Black sacrifices an exchange which can not be
declined, as, 3. Kg2 Rxc1, black wins a rook. Why has black given up a
well-placed rook for a poorly placed knight? The answer lies in the middle of
the board, on e4, to be precise. This pawn is now going to advance
unchallenged, with the black bishop on c3 playing a vital passive role. So
after white recaptures with, 3. Rxf1, black follows the maxim: "Passed pawns
must be pushed", with, 3. ... e3. Now white has no sensible means of getting in
front of the black e-pawn, and attempting to get behind the advancing be-pawn
is too slow. The key square now is e1, white can not cover this square with
more then one defending unit without losing material. Clearly, 4. Re1 Bxe1,
will not stop the advancing e-pawn. White has 2 plausible attempts, firstly to
bring the king across and secondly to defend actively with the rook
.
Variation A: White brings the king into play with, 4. Kg2, and black continues
the advance with, 4. e2, so that any white rook move, say, 5. Rc1, will be met
with, 5. ... e1=Q 6. Rxe1 Bxe1, and black is a bishop for a pawn ahead and
winning. White has one try with, 5. Kf2, hoping black will promote the pawn,
when after, 5. ... e1=Q+ 6. Rxe1 Bxe1+ 7. Kxe1, white has a won 4 against 3
king and pawn ending. However after, 5. Kf2, black captures the attacked f1
rook with, 5. ... exf1=Q+, remaining a bishop ahead and winning
.
Variation B: White tries to catch the apparently unprotected black bishop and
pawn. However, just because a piece or pawn is not actually protected, it does
not automatically mean that each are vulnerable. Black has sufficient activity
such that there are now unstoppable threats, the black advanced forces are
being protected by tactics. White can try 2 rook moves and black replies the
same to both. If 4. Rc1, black can ignore the attack and keep advancing with,
4. ... e2, since if now, 5. Rxc3 e1=Q+, a queen promotion which also picks up
the white c3 rook. Instead, 4. Rf3, laterally pinning the e3 pawn to the c3
bishop, black similarly ignores this pin with, 4. e2, with the same possible
sequence, 5. Rxc3 e1=Q+, black wins the rook. Lastly if, 4. Rf3 e2 5. Re3,
holding the pawn from the rear, simply, 5. ... e1=Q+ 6. Rxe1 Bxe1, and black is
a bishop ahead
.
** Condensed proposed solution
.
1. ... Bc3 2. Rc1 Rxf1+ 3. Rxf1 e3 4. Kg2 e2
5. Kf2 exf1=Q+
.
** Other tactical variations considered, and rejected
.
If black tries advancing the pawn immediately with, 1. ... e3, white can
capture with, 2. Nxe3. Black must be careful here, since, 2. ... Re8, pinning
the white knight will not win as, 3. Nc2, breaks the pin and protects the e1
rook. White has won a pawn. So instead after, 1. ... e3 2. Nxe3 Rf3, attempting
to regain material on the 6th rank. However this is flawed thinking as, 3. Nc2,
places an attack on the black d4 bishop, so black does not have time for, Rxb3,
yet. So, after, 3. ... Bc5 4. Rb1, white has an extra pawn, black is not
winning but instead struggling
.
** Alarm bells
.
1. The black e4 pawn had dual identities. Passed or isolated. The coordination
of the remaining black forces determined the pawn was a passed pawn, and a very
dangerous one at that
.
2. The white king clearly hid in the corner to avoid middlegame threats. This
unfortunately means it needs extra time to run towards the centre when the
endgame begins. He can't have it both ways
.
3. The black bishop immediately took control of the promotion square, with an
attacking gain of tempo on the white rook. This allowed a black deflective
exchange sacrifice, which then allowed the e-pawn to advance to win material
.
4. The white rook was forced to defend without access to important squares, the
combined attack of bishop and pawn on dark squares, control of e1 and f2, meant
the white rook could not attempt to create a blockade by sitting on the e2
square
.
Paul Benson.
. -----Original Message-----
From: R Dinger - Email Address: rrdinger@xxxxxxxxxx
Sent On: 27/07/2013 18:40
Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx
Subject: [blind-chess] Problem WAC101
Good Morning Puzzlers,
Another WAC series problem. This problem starts a new section.
This problem is from Mario Lang's puzzle web page at:
http://delysid.org/chess/epd.cgi
Problem WAC101
Black to move
FEN Problem Setup:
5rk1/
p5pp/
8/
8/
2Pbp3/
1P4P1/
7P/
4RN1K
b - - 0 1
Short Algebraic Problem Setup:
White: Kh1, Re1, Nf1, Pb3, Pc4, Pg3, Ph2
Black: Kg8, Rf8, Bd4, Pa7, Pe4, Pg7, Ph7
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