[blind-chess] Chess Article #46 Chess Tactics
- From: Roderick Macdonald <rmacd@xxxxxxxx>
- To: Blind Chess Mailing List <blind-chess@xxxxxxxxxxxxx>
- Date: Tue, 8 Jun 2010 15:08:28 -1000 (HST)
Chess Article #46
Chess Tactics
Adapted and Condensed from
Wikipedia, the free Encyclopedia
Guarding
When one of your pieces is placed so that it attacks a square
occupied by another of your pieces, the first piece is said to be
guarding the other. When your opponent captures the guarded piece,
you can recapture with the guarding piece. Note that if you have a
piece that is pinned to your king by an opposing piece (see below
for a description of pins), it can only guard other pieces against
capturing by the enemy king, but not from other enemy pieces, since
it is unable to move or capture.
Batteries
FEN: 1r3k2/
p1rqn1p1/
Ppn1p2p/
1B1pPp2/
1P1P1P2/
2R2N2/
2R3PP/
2Q3K1/
Alekhine-Nimzowitsch 1930
Position after 26. Qc1
Batteries are formed when two or more pieces work together. The
most common kind of battery is the doubling of rooks on a file.
Other batteries can be formed by rook-queen or bishop-queen.
A triple battery can be constructed with the queen and both rooks.
This is known as Alekhine's gun (diagram at right) and can be very
dangerous. It is often advantageous to place the queen behind one
or both rooks as it is a more valuable piece.
The Exchange
In pretty much any game, a player will have the opportunity to take
one of his opponents pieces in exchange for one of his own pieces.
This should however NOT be done for its own sake! Initiate an
exchange only when it benefits you. Benefits can include, but are
not limited to:
* Material advantage - queen for a minor piece, queen for rook,
rook for a minor piece, a piece for a pawn or two, etc.
* Doubling pawns - Take when taking back means the doubling (or
tripling) of your opponent's pawns on the same file.
* Opening up the king's defenses - Take when taking back means
moving a pawn that exposes the king.
* Removing a defender - Take when the piece being taken is
providing an essential service for the opponent.
* Blunting an attack - When you are being attacked, often a well
timed exchange will leave your opponent with too few pieces to
keep up the attack.
* Gaining space - In a cramped position, having more pieces can
actually be a disadvantage because the pieces get in the way
of each other. If your opponent has a space advantage,
exchanging pieces can lessen the advantage and make the
resultant less confining.
* Improving a material advantage - if you are ahead material,
exchanging pieces will usually benefit you (note - pieces, NOT
pawns). Similarly, if you have an extra pawn, trade pieces
that may otherwise be used as a sacrifice to prevent pawn
promotion.
Forks and Double Attacks
Sometimes a piece can be in position to attack two enemy pieces at
once. This is called a fork or a Double Attack. All pieces can
fork, even pawns, but knights have a reputation for making
especially vicious forks because they can jump over other pieces.
Forking with check
Forks on unguarded squares which attack the king are the most
powerful. The opponent must then move his king to safety and the
other piece in the fork has no chance of escape.
The Royal Fork
FEN: rnbqr2k/
pppp1Npp/
5n2/
4p3/
4P3/
8/
PPPP1PPP/
R1BQKBNR/
The Royal Fork
A royal fork is one involving both your opponent's king and queen.
In the example shown here, white's knight on f7 has engaged black
in a Royal fork. Black will be down the exchange of a queen for a
knight.
Forks do not always win material
FEN: 7k/
r6p/
2p3p1/
p7/
P2Q4/
6P1/
6KP/
8/
A Queen Fork - Black to Move
If every time you saw a fork you played it, you would be making a
mistake. You have to examine the different possibilities to escape
the fork. In the queen fork on the right white has just played
1.Qd4+ forking the black king and rook. However black can play 1.
... Rg7 blocking the check and moving the rook to safety.
However Qd4 is by no means a bad move. Perhaps white played Qd4 in
order to force black to play Rg7 in which white can now play 2.Qd8+
Rg8 (forced) followed by 3.Qxa5 in which case white can push his a-
pawn. Here white forked black's king and rook not to win the rook
but to win a pawn and pave the way for his a-pawn to become a
queen.
Pinned pieces
FEN: 4k3/
ppp2ppp/
5n2/
8/
1b2P3/
2N5/
PPP2PPP/
4K3/
The white knight pinned by the black bishop
A pinned piece is a piece that cannot move because it would expose
an attack on an important piece by one of the opposing pieces, such
that the capture of the important piece would result in material
gain by the opponent. A very useful device is to pin the opponent's
pieces to his king; this is known as an absolute pin. For example,
imagine white's king on e1, a white knight on c3, and d2 empty.
Black now moves his dark-squared bishop to b4. The white knight is
now pinned and cannot move. A pawn on e4 is no longer guarded by
the knight, which could not capture a black piece taking this pawn.
FEN: 7k/
pp1n1rpp/
2p5/
8/
2BP4/
5N2/
P4PPP/
6K1/
Attack the pinned piece, white to move
In contrast to the absolute pin, a relative pin occurs when one
player's piece is pinned to one of lesser value than the king, such
as a queen or rook. If the benefit of moving the pinned piece
outweighs the loss of material occasioned by the capture of the
exposed piece (for example, if a forced mate may be achieved), then
the pin can be disregarded and the pinned piece moved.
The position diagrammed above shows the theme of attacking the
pinned piece. In this position it is white to move. The white
player can look at this position and immediately take the rook and
win an exchange. However if he did this he would not be playing the
BEST move. If white did this then the material would be dead even;
however, white has more pawn islands and it would be a very close
game. White can instead play Ng5! The rook cannot move, and black
has no way of effectively defending the rook a second time in the
next move, therefore in the end result black will lose a rook and
not gain anything back. So, if you have pinned a piece take a look
to see if you can attack the piece again, and if a piece of yours
is pinned take a look to see if your opponent can attack it again.
And above all else, if you see a good move stop and look around for
the best move.
Skewers
FeN: 3q4/3k1ppp/8/8/8/8/PPP2PPP/R4RK1/
Skewer about to happen
A skewer is similar to a pin, but it is in a sense more powerful.
Black has, in a blunderous moment, placed his king on d7 in front
of his queen on d8. White may now triumphantly slide his rook
(either one) to d1, skewering Black's king and queen. Since Black
cannot block the check, the king has to move, exposing the black
queen to the attack of the white rook.
Discoveries
A discovery is an attack on an enemy piece which is unveiled by
moving one of your pieces. The power of discoveries is that two
targets can be attacked simultaneously. If combined with a check
they can be lethal.
FEN: 1kr3nr/
pp3ppp/
8/
P3N3/
3P1B2/
6P1/
1PP2P1P/
R4RK1/
If white moves his knight ...
1. Nd7+
FEN: 1kr3nr/
pp1N1ppp/
8/
P7/
3P1B2/
6P1/
1PP2P1P/
R4RK1/
... it's a discovered check ...
1. ... Ka8
FEN: k1r3nr/
pp1N1ppp/
8/
P7/
3P1B2/
6P1/
1PP2P1P/
R4RK1/
... and after he moves ...
2. Nb6+
FEN: k1r3nr/
pp1N1ppp/
1N6/
P7/
3P1B2/
6P1/
1PP2P1P/
R4RK1/
... a sacrifice ...
FEN: k1r3nr/
1p1N1ppp/
1P6/
P7/
3P1B2/
6P1/
1PP2P1P/
R4RK1/
... and after
3. ... axb6
4. axb6
it's another discovered check and mate!
Note that White's 1. Nd7+ was a double check, a type of discovered
check where the piece moving also gives check. Such checks are very
powerful, since the king is forced to move (both checks cannot be
blocked at the same time). They are also often lethal, as in the
above game.
Removing the defender
By first capturing, threatening, or pinning a piece that guards
another, you might be able to capture the other piece for free.
Sacrifices
A sacrifice is an exchange of a piece for a non material advantage:
FEN: k1r3nr/
1p3ppp/
1P6/
8/
3P1B2/
6P1/
1PP2P1P/
R4RK1/
In the first diagram, White just moved 1. Kh1 to get out of check.
FEN: 5k2/
ppp2ppp/
1q6/
8/
8/
7n/
PPP3PP/
R4R1K/
Position After 1. Kh1
2. qg1+
FEN: 5k2/
ppp2ppp/
8/
8/
8/
7n/
PPP3PP/
R4RqK/
Position After 1. ... Qg1+
Black sacrifices his queen with 1. ... Qg1+ for a winning
positional advantage - White is in check and can not take with his
king because the knight guards the queen.
2. Rxg1 - forced - this smothers the king - he cannot move because
his own pieces are on every square he could go to - any check on an
unguarded square now is mate.
FEN: 5k2/
ppp2ppp/
8/
8/
8/
7n/
PPP3PP/
R5RK/
After 2. Rxg1
2. ... Nf2#
FEN: 5k2/
ppp2ppp/
8/
8/
8/
8/
PPP2nPP/
R5RK/
Position After 2. ... Nf2#
Checkmate. This queen's sacrifice was an example of a smothered
mate (in which a knight delivers a checkmate that is caused by the
king's inability to move anywhere).
In-between moves
stop here
a8 b8 c8 d8 e8 f8 g8 h8
a7 b7 c7 d7 e7 f7 g7 h7
a6 b6 c6 d6 e6 f6 g6 h6
a5 b5 c5 d5 e5 f5 g5 h5
a4 b4 c4 d4 e4 f4 kd g4 h4
a3 b3 pd c3 d3 e3 f3 pd g3 rl h3
a2 bd b2 kl c2 d2 e2 f2 g2 h2 pl
a1 b1 c1 d1 e1 f1 g1 h1
Before 1. ... f2
a8 b8 c8 d8 e8 f8 g8 rl h8
a7 b7 c7 d7 e7 f7 g7 h7
a6 b6 c6 d6 e6 f6 g6 h6
a5 b5 c5 d5 e5 f5 g5 h5
a4 b4 c4 d4 e4 f4 kd g4 h4
a3 b3 pd c3 d3 e3 f3 g3 h3
a2 b2 kl c2 d2 e2 f2 pd g2 h2 pl
a1 b1 bd c1 d1 e1 f1 g1 h1
After 2. ... Bb1! (white resigned)
An in-between move or Zwischenzug is one that is made unexpectedly
in the midst of a sequence of moves. But not just any series of
moves, one in which the player falling for the Zwischenzug feels
the sequence is forced, while his opponent demonstrates to him that
it certainly isn't! Most commonly these fall in between trades
where a recapture seems to be the only proper means of play.
Such in-between moves often have a surprising and pleasing effect
of increasing the potency of a combination beyond the opponent's
expectations.
Borisenkov-Mezenev (diagram, Black to play), went 1. ... f2,
threatening to queen, which White countered with 2. Rg8, intending
3. Rf8+, and 4. Rxf1. But White resigned after the zwischenzug 2.
... Bb1! which allows Black to queen (3. Kxb1 f1Q+ or 3. Rf8+ Bf5).
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