[blind-chess] Spoiler Alert: Problem WAC100 - Patience Is A Virtue
- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Sun, 16 Dec 2012 19:21:46 -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: Three pawn islands and a pawn up. The white king is in no danger, and as
such would like to infiltrate the black position, though black appears to have
set up a blockade. The bishop on d2 is tied down to defending the f4 pawn, a
pawn which can not be given away without finding good compensation elsewhere on
the board. The 3 connected queenside pawns are being blockaded by the combined
forces of the black king, bishop and c5 pawn. The kingside f4 and h4 pawns are
fixed, and so are vulnerable on dark squares
.
Black: Three pawn islands and a pawn down. The king is combining with the c7
bishop to restrain further advance of the white queenside pawns. The c5 pawn is
preventing the white king from using the b4 and d4 squares. The 3 black
kingside pawns are reduced in effect to 2 pawns, illustrating here how
sometimes doubled pawns are really only worth a single pawn. This
generalisation is found to be most valid when the position is blocked, with
little or no chance of a dynamic opening of the position on that side of the
board
.
** Hints section, 5 hints
.
Hint 1, to find the key move
.
The festive season is approaching, so wrap this one up
.
Hint 2, to find the key move
.
Quotation from the Godfather: Don Corleone: "I'm gonna make him an offer he
won't refuse"
.
Hint 3, to find the key move
.
Invest small for a large return
.
Hint 4, to find the key move
.
Does this bring a lightning strike to mind?
.
Final hint, to find the key move
.
There must be a royal invasion, but how to proceed?
.
** Proposed solution to WAC100
.
White has a dynamic means of improving the king with a temporary pawn
sacrifice, being, 1. b6+. This forks king and bishop, so this can not be
declined. Black now has 2 replies
.
Variation A: Black plays, 1. ... Kxb6, which allows white to win a piece with,
2. Ba5+. If the black king captures the now unprotected white a6 pawn, then
simply, 2. Bxc7, and white is a bishop ahead and winning. Instead, after, 2.
Ba5+, the black king can keep a guard on the c7 bishop with, 2. ... Kc6. Now
white overloads the black king with, 3. a7, and the only way for black to
prevent this pawn from promoting is, 3. Kb7. Now the simplest win for white is,
4. Bxc7, and the overloaded black king can not capture both the
about-to-promote a7 pawn and bishop on c7. White will also quickly win the
black c5 pawn, and is thus winning
.
Variation B: Black captures with, 1. ... Bxb6. White must now advance the king,
with 3 purposes in mind. This puts pressure on the black c5 pawn, defends the
a6 pawn, but most importantly, offers the king entry into the black queenside.
Note, if instead, 2. Ba5, black achieves an easy draw with, 2. ... Kxa6. So,
now the white king has advanced, black must move, and obviously a black king
retreat will lose the bishop on b6. So, a black bishop move is demanded and the
most sensible is, 2. ... Bc7, placing pressure on the white f4 pawn. Now white
shows how a bishop can both defend and attack simultaneously with, 3. Be3. This
maintains the defence of the f4 pawn, and now also attacks the unprotected
black c5 pawn. Note, if instead white tries, 3. Kxc5, white will still be
winning, but black will be given the luxury of removing the white a6 pawn with,
3. ... Kxa6. White does not need to give away the a6 pawn, and as will soon
become apparent, this pawn severely restricts the black king and bishop
mobility. So after, 3. Be3, black must be careful. Either, 3. ... Bb6 4. Bxc5,
or, 3. ... Bd6 4. Bxc5+, and in both cases bishops will be traded off, leaving
white with a won king and pawn ending. So after, 3 Be3, black can try, 3. ...
Ka8, though it does not really matter what black tries, as the white plan can
not be prevented. Now, 4. Kxc5, and the 2 extra queenside pawns are going to
cost black a bishop. Note, white can even march the king into the black
kingside here, to snatch even more pawns, but the chosen plan offered here
seems rather neat and instructive. Black can try, 4. ... Kb8, and white should
resist the temptation to advance the pawn to a7, it is quite well placed on a6,
controlling the b7 square. So white instead infiltrates with, 5. Kc6, which
contains a threat of, pawn a7+, which would deflect the black king from
defending the black c7 bishop. So, black must move the bishop and the most
sensible seems, 5. ... Ba5. White keeps the king infiltration going with, 6.
Kd7, and black has no means to halt the advance of the white c4 pawn. There are
still however some tricks black can try. After, 6. ... Ka8 7. c5 Kb8 8. c6,
black can set a trap with, 8. Bc7. White must tread carefully here, the black
king is hoping for a stalemate in the corner. White continues with, 9. a7+,
forcing the black king into the corner with, 9. ... Ka8. White must not capture
with, 10. Kxc7, which is blundering into a stalemate. Instead, white is
prepared to lose the a7 pawn for the black bishop, and the simplest way is a
white bishop retreat off the g1-a7 diagonal with, 10. Bd2. The black king can
not move to protect the black bishop so, 10. ... Bb6, is all there is, and now
the white c-pawn advances with, 11. c7. Clearly, 11. ... Bxc7, 12. Kxc7, and
white wins, as the black king can legally take the a7 pawn. So instead black
tries, 11. ... Kb7, but, 12. c8-Q+ Kxa7 13. Kc6, and white, 14. Qb7+ mate is
unpreventable
.
** Condensed proposed solution
.
1. b6+ Bxb6 2. Kb5 Bc7 3. Be3 Ka8 4. Kxc5 Kb8
5. Kc6 Ba5 6. Kd7
.
** Other tactical variations considered, and rejected
.
White could miss the above opportunity, of the dynamic temporary sacrificial
opening of the queenside, permitting entry of the king, by attempting to follow
another concept, that of trying to further increase the pressure on the
position with, 1. Be3. This just allows black to successfully complete the
queenside blockade with, 1. ... Bb6. Assuming white is never going to find the
idea of pushing the b-pawn, should it become possible, then white now has no
means to win. If, 2. Bf2, keeping the pressure on the c5 pawn, black simply
plays, 2. ... Kb8, and white can make no further progress, as black keeps
shuffling the king between a8 and b8. If white tries to correct matters by
trying to dislodge the black bishop from b6 with, 3. Be1, then black retreats
with, 3. ... Bc7, which keeps pressure on the important white f4 pawn, which
can not be casually jettisoned by white. Again, assuming white will not find
the idea of giving up the b5 pawn, letting the white king infiltrate, then
there is no way to break through, black achieves a draw
.
** Alarm bells
.
1. The window of opportunity for a decisive move may only be open once,
constant vigilance is necessary if the chance is to be taken
.
2. The white king was apparently shut-out of advancing into the centre by one
of his own pawns. The solution: Give the blocking pawn away, and use the
vacated square as an entry point
.
3. The white bishop subtly moved to a parallel diagonal, effectively doubling
the work load, maintaining a necessary defence while creating an attack on a
newly exposed weakness
.
4. The first part of the plan was to advance the white king as far into the
black position as possible. Only then was the passed pawn finally permitted to
get moving. This sequence of steps will have shortened the game considerably
.
5. White retained the outside passed a-pawn, until the position was so strong
that it became dispensable. Recognise when a unit is no longer necessary to the
overall cause, and be prepared to let it go for bigger gains elsewhere
.
. Paul Benson.
-----Original Message-----
From: R Dinger - Email Address: rrdinger@xxxxxxxxxx
Sent On: 09/11/2012 19:02
Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx
Subject: [blind-chess] Problem WAC100
Good Morning Puzzlers,
Another WAC series problem. This will finish the fifth section.
This problem is from Mario Lang's puzzle web page at:
http://delysid.org/chess/epd.cgi
Problem WAC100
White to move
FEN Problem Setup:
8/
k1b5/
P4p2/
1Pp2p1p/
K1P2P1P/
8/
3B4/
8
w - - 0 1
Short Algebraic Problem Setup:
White: Ka4, Bd2, Pa6, Pb5, Pc4, Pf4, Ph4
Black: Ka7, Bc7, Pc5, Pf5, Pf6, Ph5
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