[blind-chess] Spoiler Alert Problem WAC083
- From: "Paul Benson" <paul.benson@xxxxxxxxxxxxxxx>
- To: <blind-chess@xxxxxxxxxxxxx>
- Date: Mon, 12 Sep 2011 17:52:53 +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. There are no weaknesses in either the queenside or
kingside pawn structures. The king is safe from immediate attack, but the
unmoved kingside pawns mean there is always the possibility of a back rank
mate. The queen is centrally placed, and is combining to place pressure on the
black d7 bishop. She is also attacking the undefended black a7 pawn, though at
present it is not safe to capture this pawn. The d1 rook is combining with the
queen down the d-file, placing the d7 bishop under severe pressure. The e7 rook
has not only found it's way onto a fully open file, but has also managed to
penetrate to the 7th rank, two favourable factors for a rook's placement. It is
however, unprotected and is also under attack from the black e8 rook. The c2
bishop, for attacking purposes, is pointing into the black kingside, and for
defensive purposes, is offering protection of both the d1 rook, and the d1
square itself. The g3 knight is ready to move forward if appropriate, however
it might be advised to stay where it is, preventing the black f4 knight from
landing on e2, with a royal checking fork, which at present would cost white an
exchange
.
Black: Two pawn islands. There are no weaknesses in either the queenside or
kingside pawn structures. The a7 pawn can be captured, though tactics presently
in the position, means that it is safe for the moment. The king has no piece
protection nearby, though the white pieces are not combining well for a direct
attack against the black king. The unmoved kingside pawns mean there will
always be the danger of a back rank mate, once any tactics start flowing. The
queen is uncomfortably placed on c7,she is in a pin through the d7 bishop from
the white e7 rook, not a happy situation. Both of the rooks has found their way
to a central fully open file, normally desirable, however here matters are not
so simple. The d8 rook has it's action blocked by it's own bishop, however, the
e8 rook is at least trying to negate the influence of the advanced white e7
rook. The d7 bishop is in all sort of problems. It is defended only twice,
while being attacked 3 times by the white heavy pieces, note the battery of
white queen and rook down the d-file. The f4 knight has made an advance which
does not coordinate well with the rest of the black army. However, some
attacking opportunities for this piece must be always considered by white, when
any tactics begin
.
** Hints section, 5 hints
.
Hint 1, to find the key move
.
Identify a serious weakness in the black position
.
Hint 2, to find the key move
.
The white e7 rook is undefended and can be captured. You are going to do
something about it, right?
.
Hint 3, to find the key move
.
Sometimes an attacking move has secondary defensive properties
.
Hint 4, to find the key move
.
The central pressure looks very strong for white
.
Final hint, to find the key move
.
Taking pawn-count piece values into consideration, think the unthinkable
.
** Proposed solution to WAC083
.
White has built up a superior position, and as Bobby Fischer tells us: "Tactics
flow from a positionally superior game". The only problem, is that when you
have such a strong position, sifting the best line from many tempting
variations, can take some hard work. Clearly the weakest black piece is that d7
bishop, and white has been building pressure there for a few moves. Combine
this with a potential for a back rank mate, a familiar theme in quite a few of
these problems, and white has a killer blow. It starts with, 1. Qxd7. Yes, the
queen heads the charge. Black has 3 possible replies
.
Variation A: The worst of all is, 1. ... Rxd7, which leaves the back rank
unguarded and so, 2. Rxe8+ is mate
.
Variation B: Equally losing for black is, 1. ... Rxe7, and the newly weakened
back rank is the target again for white. It goes, 2. Qxd8+, leaving black with
no real choice other than, 2. ... Qxd8 3. Rxd8+ Re8 4. Rxe8+ mate
.
Variation C: The best test of white's play is the black reply, 1. ... Qxd7. Now
white must be careful. One rook recapture on d7 wins for white, the other
loses. If, 2. Rexd7, black wins material or gives mate with, 2. ... Rxd7. White
is now an exchange down, but can take that black d7 rook. However after, 3.
Rxd7, black now invades with, 3. ... Re1+, and the reply from white is forced,
4. Nf1. So, white is a piece up, and threatens to mate black on d8 next move.
Black has a shock in store for white, the f4 knight has just been hanging in
mid-air, waiting to jump into action. It is, 4. ... Ne2+, white has no choice
but, 5. Kh1, and the king has been deflected away from defending the f1 knight,
and so, 5. ... Rxf1+ is mate
.
So, still examining the black capture of, 1. ... Qxd7. White now tries the
alternate rook move of, 2. Rdxd7. This keeps both the central files closed, so
no play for black here. Black has the problem of being vulnerable to a back
rank mate, so either attempted rook capture leaves it's partner undefended. If
black tries, 2. ...Rxd7, then, 3. Rxe8+ is immediate mate. Instead if black
goes, 2. ... Rxe7 3. Rxd8+ Re8 4. Rxe8+ is mate. So, the white rooks doubled on
the 7th rank are immune. Black has no sensible way to disrupt this white
formation. If 2. ... Nd5, the simplest and safest for white is, 3. Rxd8, though
3. Rxf7 and sweeping up many black pawns will clearly win. So, black must
recapture with, 3. ... Rxd8, and while keeping the white rook active in some
way will be fine, denying black any thoughts of play with, 4. Re1, seems a good
choice. White will slowly re-group, giving black not a sniff of counterplay
.
** Condensed proposed solution
.
1. Qxd7 Qxd7 2. Rdxd7 Nd5 3. Rxd8 Rxd8 4. Re1
.
** Other tactical variations considered, and rejected
.
Option 1: White can try to win the doomed d7 bishop with, 1. Rxd7, but this
backfires as follows. Black simply wins with, 1. ... Rxd7. Note, the capture,
1. ... Qxd7 will be discussed later. So, if white is not wishing to remain an
exchange down, there must be, 2. Qxd7 Qxd7 3. Rxd7. This looks fine for white,
doesn't it? Well, black now inflicts a back rank mate with, 3. ... Re1+, and
the white reply is forced, 4. Nf1. If white was hoping this knight intervention
was salvation, then disillusionment is swift. Black plays, 4. Ne2+, which
forces the white king away from protecting the f1 knight, 5. Kh1 Rxf1+ is mate.
In this line, the previously very secure white back rank, was fatally weakened
by continually capturing on d7. Also, the black knight on f4, who could not do
anything by force, was permitted activity because white lost control of the
e-file, and in particular the e2 square
.
Still examining for white, 1. Rxd7, now the alternate capture of, 1. ... Qxd7.
Note, a transposition to the losing line for white just given can occur, if
white chooses, 2. Qxd7. However, the black queen has been deflected from a
defensive duty, that of defending the f4 knight. White has, 2. Qxf4, and white
has for the moment, won 2 pieces for a rook. Black might now have to play for
complications in a material imbalance ending, of queen versus 2 rooks. If
instead, 2. ... Qe7, a rather passive choice which leaves white to prove the
material advantage is winning, which with good technique should be so, but it
is not an easy task. So, if black wishes to play actively, then it has to be,
2. ... Qxd1+, which starts a forcing sequence of, 3. Bxd1 Rxd1+ 4. Nf1. Black
is trying to exploit a weak white back rank, but as it happens, black is in
exactly the same danger. If black tries, 4. ... Ree1, apparently winning the
already pinned white knight, then, 5. Qb8+, and black can only postpone being
mated himself by giving up both rooks. So, black can not double on the 8th rank
immediately, and should play, 4. ... g6, giving the king a flight square. So
now the doubling rooks threat is on again. White must create an escape route
for the king, so, 5. g3 Ree1, and black will win the knight. Here white could
play for an equal pawn ending with, 6. Qc4, and multiple captures on f1 produce
nothing for either player. Instead, if white wishes to play on for a win, then
it must be, 6. Qb8+. Note, in an ending of queen against 2 rooks, the pawn
structure for the side with the rooks is very important. Any pawn weaknesses
will be ruthlessly exploited by a marauding queen, which will attack in several
directions at once. Play might continue, 6. Qb8+ Kg7 7. Qxb7, and now the black
queenside pawns are split and vulnerable. According to material count, the game
is equal after, 7. ... Rxf1+ 8 Kg2, and black must win all the white queenside
pawns as quickly as possible. White in turn, must keep the queen active, and
always maintain the option of a perpetual check on the black king, should the
black rooks threaten to win all the queenside pawns. Chances in this ending are
roughly equal, but this is difficult to play and either player could go wrong
very easily
.
Option 2: White can try, 1. Rxe8+, which forces the reply, 1. ... Rxe8. Note,
if, 1. ... Bxe8, black loses a rook on d8 with, 2. Qxd8. Now, white can fall
for the previously given trap of, 2. Qxd7, winning a piece but getting back
rank mated. The initial trade of rooks on e8 has gained white nothing, and
missed the win
.
Option 3: The other queen sacrifice must be examined as well, so, 1. Qxf4,
which forces the reply of, 1. ... Qxf4. Now white has the similar trick to that
given in the proposed solution of, 2. Rdxd7. So white has 2 pieces for a queen,
not enough, and black now has the simplifying, 2. ... Kf8. Note, black must not
make either rook takes rook capture, which allows white to make a rook takes
rook counter-capture giving mate. Now the white e7 rook is doubly attacked, and
white must trade at least one pair of rooks, and in doing so, all potential
threats evaporate, black is winning. Instead, 3. Rxf7+, trading the 2 white
rooks for the black queen and a pawn, leaves white 2 exchanges down, and lost
.
Option 4: White can try for the rather crude threat of mate with, 1. Nf5,
attacking g7 with the queen and knight. There are some really fancy lines for
white, if black goes wrong. Attempting to block the diagonal with, 1. ... f6,
only opens up the 7th rank for the white rook. Play could go, 2. Rxg7+ Kh8.
Note, 2. ... Kf8, allows an immediate demise with, 3. Qxf6+ mate. So, now white
removes a defending pawn with, 3. Qxf6, which sets up some wonderful discovered
check threats for the next white move. If black tries any of, 3. ... Rf8, or,
3. ... Re6, or, 3. ... Nh5, then white responds to all 3 moves with, 4. Rg8+.
This is a discovered double check, which means that both the checking pieces
can not be captured simultaneously. The only way to get out of a discovered
double check is to move the attacked king. Here there is only one legal move,
4. ... Kxg8, but now comes a lovely reply from white, 5. Nh6+ mate. This
demonstrates how a defending king restricted in movement by an attacking queen,
as close as is possible to be without giving check, can combine with a knight,
for a mating pattern worthy of more than a casual glance. Black has 2 more
replies to consider after white plays, 3. Qxf6, the first is, 3. ... h5, which
breaks the queen and knight mating pattern, but simply allows, 4. Qh6+ mate.
Lastly, after, 3. Qxf6, black could play, 3. ... Bxf5. This gives white several
choices again for a discovered check, and this time any move along the 7th
rank, other than capturing on h7 with check, such as, 4. Rxc7+, wins. If, 4.
... Kg8, then, 5. Qg7+ is mate. Note, at any point when black had a free move,
spite checks could have been thrown in with either the f4 knight or the e8
rook, but nothing will have been altered
.
So far, white appears to have a winning move with, 1. Nf5. Black must find
something stronger than trying to block the diagonal. Well, surely black can
not capture that knight with the d7 bishop, because the black queen could be
captured by the e7 rook in reply. Ah, but the white queen has also been placed
under a discovered attack, from the black d8 rook, when the d7 bishop captured
the knight. So, it appears black has, 1. ... Bxf5, which forces white to choose
between 2 captures. The first capture is, 2. Rxe8+, which forces the d8 rook
away from attacking the white queen with, 2. ... Rxe8. Now white regains the
piece with, 3. Bxf5, but now comes disaster. White no longer controls the e2
square, and a royal fork is given with, 3. ... Ne2+, and black wins the white
queen. If white does not play, 3. Bxf5, then black remains a piece up. So, has
white anything better after, 1. ... Bxf5. How about, 2. Rxc7, but now black has
a similar trick as just noted above in, 2. ... Ne2+, that royal fork again,
since both the previous white defenders of this square have deserted their
posts. After, 3. Kf1, black continues with, 3. ... Nxd4. Black is still a piece
ahead, and white can take both of them next move, but will still remain a piece
down. It goes, 4. Bxf5 Nxf5, and the knight recaptures and escapes being
captured. Insteadif white tries, 4. cxd4, then the c2 bishop is lost with, 4.
... Bxc2, and black is a piece ahead. Note, how in all of this, black did not
capture the white queen with the d8 rook. This would leave black with 2 pieces
for a rook, which is not so clear as just winning a piece
.
So, still examining, 1. ... Bxf5. Since both queens are attacked, white must
consider the idea of giving up the queen, before capturing the black queen. So,
white can try, 2. Qxd8, black must be careful. Firstly, if, 2. Qxe7, a blunder
by black. White wins with, 3. Qxe7, since, 3. ... ... Rxe7, allows white, 4.
Rd8+ mating next move. The second capture for black is, 2. ... Rxd8, and is bad
for black. There would follow, 3. Rxc7, rooks are opposed down the d-file and
the f5 bishop is hanging, and black is also an exchange down. If, 3. ... Rxd1+,
then white is forced to play, 4. Bxd1, and the attacked bishop moves out of
danger, white is an exchange up and winning. Any black rook move such as, 3.
... Re8, just loses another piece with, 4. Bxf5. So, has black anything
against, 2. Qxd8, by white? Yes, simply, 2. ... Qxd8, which gives white no
choice but to play, 3. Rxd8. It looks as if material equality is about to
emerge, but there is a sting in the tail. Black must play, 3. ... Rxd8, and now
white is lost. The c2 bishop wants to play, 4. Bxf5, but this leaves the back
rank unguarded and, 4. ... Rd1+ will be mate. So, black stays a piece up and
wins
.
It appears that white throwing the knight forward with, 1. Nf5, creates
complications, and puts black to the test. It is refuted by, 1. ... Bxf5, but
this move requires careful analysis to prove that white is going to lose
.
** Alarm bells
.
1. Even though white has a much superior position, care must be taken to
calculate counterplay, generated when pieces previously passive, are released
from defensive roles, as captures progress and the reason for those pieces
having to defend, no longer applies
.
2. Both kings were vulnerable to back rank mates. If calculating tactics
accurately is a skill yet to be mastered, it might be prudent at some point in
the early middle game, to take time to break the potential mating pattern,
before tactics begin to become an important factor. This will however, also
possibly create a slight weakening, which may become a target for attack. You
can't have it all
.
3. The black knight has used a minimum of 3 moves to reach the f4 square.
Perhaps it might have been advisable for black, earlier on to use a couple of
those moves, to make a challenge to white in the centre, before the pressure
became critical
.
4. When there are several ways to initiate a sequence of captures, in this
case, either rook or queen first, both should be considered. However, bear in
mind, queen sacrifices are never as common in reality, compared to the world of
books studying tactics and combinations
.
Paul Benson.
-----Original Message-----
From: R Dinger - Email Address: rrdinger@xxxxxxxxxx
Sent On: 06/09/2011 16:38
Sent To: chess - Email Address: blind-chess@xxxxxxxxxxxxx
Subject: [blind-chess] Problem WAC083
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 WAC083
White to move
FEN Problem Setup:
3rr1k1/
ppqbRppp/
2p5/
8/
3Q1n2/
2P3N1/
PPB2PPP/
3R2K1
w - - 0 1
Short Algebraic Problem Setup:
White: Kg1, Qd4, Rd1, Re7, Bc2, Ng3, Pa2, Pb2, Pc3, Pf2, Pg2, Ph2
Black: Kg8, Qc7, Rd8, Re8, Bd7, Nf4, Pa7, Pb7, Pc6, Pf7, Pg7, Ph7
No virus found in this incoming message.
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19:35:00
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