Line Strategy
Peter's Problem World with FIDE Master of Chess
Composition
Peter Wong
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Note that Peter's articles, follow a chess problem
convention in using ‘S’ to represent the knight
(from the German word,
Springer). ‘N’ is reserved for a fairy piece called the nightrider.
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Problem
themes of the strategic variety are based on the concrete
departure and arrival effects of moves.
Such strategic ideas may be divided into two
main types, those that involve the occupation of squares (the subject
of the previous article), and those that focus on lines, as utilized
by the three long-range pieces: queen, rook, and bishop.
Line play in comparison offers a greater
range of possible effects, and indeed it is a broad category encompassing
many different concepts, such as the
battery, line clearance and pins.
But here we will limit our discussion to the
primary ideas of line-opening and line-closing, and look at some
directmates that elaborate on their use in striking ways. |
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Requiring only ten pieces, Problem 121 demonstrates intricate line
strategy, and shows how a single move can entail multiple line-opening and
-closing effects.
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White starts with 1.Re7! to
threaten 2.Rd7. Any move of the black knight will foil the
threat by unblocking the black bishop’s path to d5. However, a
knight move will also clear the file for the white rook to attack e5
(a potential
flight), so that after a ‘random’ placement, e.g. 1…Sd8,
2.Be3 is enabled.
The knight can make a correction
– stops this ‘secondary threat’ of 2.Be3 – by shutting off the
white bishop. But in doing so, with 1…Sf4, the knight
also interferes with the black rook, and so permits 2.Qe4.
Hence, two lines are opened and two closed by this
defence, producing a scheme known as four-way play.
Another four-way move is 1…Sg5;
again it shuts off the bishop and interferes with the rook, allowing
2.Bg7. |
121. Gustav Källgren
Tidskrift för Schack 1942
   
 
 
 
Mate in 2 |
(Also,
1…c4 2.Qe3, and 1…Rg5/Rg7/Re4 2.Qe4.)
The
three-mover 122 illustrates the Novotny, a theme closely related
to the
Grimshaw. In the diagram, Black’s rook and bishop are each
guarding against a knight mate, and their lines of defence intersect on e6.
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If White places a piece on e6, both lines
are shut off, so that the capture of this piece by either the rook or
the bishop will still leave one mate undefended. Such a white
sacrifice on the intersection of two defensive lines is called a
Novotny, and here it appears as the threat after a fine key,
1.Rh7!, viz. 2.Qe6+ forcing 2…Rxe6 3.Sf4 or 2…Bxe6 3.Se8. The
knight gives two attractive indirect battery mates.
A typical way for Black to answer a
Novotny threat is to play one of the line-pieces across the critical
square, so 1…Re7 and if 2.Qe6+? Bxe6 stops both mates, but
now 2.Sf5+ Bxf5 3.Qxe7.
A similar defence by the bishop, 1…Bg4,
sets off an even more thematic variation, when White replies with a
different Novotny, 2.Se6. This move cuts off the two
black pieces again but threatens new queen mates, which are separated by
2…Rxe6 3.Qd7 and 2…Bxe6 3.Qe7. |
122. Helmut Pruscha
Deutsche Schachzeitung 1959
1st Prize
Mate in
3 |
Lastly,
Black can take the flight given by the key, 1…Ke5 2.Se6+ Kd6 3.Qe7,
or 2…Ke4 3.Sc5.
Problem
123’s play revolves around the closure of two white lines of guard,
Qa4-d4 and Bh8-d4. The c5-knight begins with various
tries that contain double-threats, but they are handled by Black because
one of the threats entails a white self-interference, a weakness that will
potentially leave d4 unguarded.
The
first try 1.Se4? threatens 2.Sc3 and 2.Sf6. Both knight mates are
neutralised by 1…b4!: it covers c3 directly and also shuts off the white
queen, so that 2.Sf6 – interfering with the bishop’s control of d4 – does
not mate.
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An analogous try is 1.Sd3?, which
threatens of 2.Sf4 and 2.Sb4. It is
refuted by 1…e5!, which defends f4 and prevents the other knight
mate by shutting off the bishop, since 2.Sb4 would close the queen’s
line to d4.
A third try 1.Sa6?, threatening 2.Sc7 and
2.Sb4, is similarly defeated by 1…f6!, which activates the black rook’s
defence of c7, and again cuts off the bishop to stop 2.Sb4 indirectly.
In the
actual play, White’s key 1.Sd7! threatens another pair of
mates, 2.Sb6 and 2.Sf6. Remarkably, Black parries them by using
the same defensive strategy as that seen in the
try play. 1…S5c4 covers b6 directly and shuts off the
queen to disable 2.Sf6, forcing a new mate 2.Qa8. And
1…S3c4 thwarts both threats for the same reason, and leads to
2.Qxb5. |
123. Herbert Ahues
Die Schwalbe 1987
1st Prize
Mate in 2 |
A wealth
of line effects, executed by both White and Black, occur in Problem 124.
First note how Black is preventing two white mates in the diagram: Rxd4 is
stopped by the black knight, and exd4 is stopped by the black queen.
The
thematic move 1…Sd2 seemingly would admit both mates, by unguarding d4 and
interfering with the queen’s line. But in fact neither mate works,
because the knight move has also opened two black lines, allowing the
a2-bishop to pin the white rook, and the a3-rook to control e3.
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Now consider White’s play. After
moving the f4-knight to open the f-file, White threatens 2.Qf3. A
‘random’ knight move, such as 1.Sh3? because it has no additional
effects, is refuted by the thematic defence 1…Sd2!
White attempts to improve on this try by
picking a square for the knight that will close, in anticipation, a line
that Black wants to open. So 1.Sd3? to block the third rank: 1…Sd2
2.exd4. However, 1.Sd3? also closes the c2-e4 diagonal, and
consequently it is defeated by 1…Qxc2!, when 2.Bxc2 no longer mates.
Another try, 1.Sd5?, intercepts the pin
line: 1…Sd2 2.Rxd4 – a
changed mate. But the a8-e4 diagonal is also closed by this
try, enabling Black to answer with 1…Ra8!, and White cannot mate with
2.Qxa8.
Finally, 1.Se6! works by avoiding
the self-interferences: 1…Sd2 2.Rxd4, 1…Qxc2 2.Bxc2,
1…Ra8 2.Qxa8, and 1…Rg3/Rxg2/Rf4 2.Qf4. |
124. Herbert
Ahues
Hans-Dieter Leiss Memorial Tourney 1996
3rd Prize
 
 
Mate in 2 |
More complex line strategy is
seen in Problem 125, which brilliantly combines the Novotny theme
with white Grimshaws.
Black’s thematic pieces are the
d8-rook, h2-bishop, and g8-bishop, and initially they prevent the white
mates Sd4, Sc7, and dxc4, respectively. By playing to the Novotny
squares, d5 and d6, White will shut off two of the black pieces and threaten
two mates.
However, the white pieces
available to do this – the two rooks and bishops – have important duties in
controlling c5 and c6, and when they make the Novotny moves, they also
interfere with one another’s guard of these potential flights.
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In three of the four cases, Black is able
to take advantage of these white Grimshaws and hence defeats the white
moves.
The first try is 1.Rd6? (threats: 2.Sd4
and 2.Sc7), which stops the f8-bishop from attacking c5, and it is
refuted by 1…Be5!, when Black guards d4 directly and shuts off the
f5-rook (2.Sc7+ Kxc5).
The second try, 1.Bd6? (2.Sd4 and 2.Sc7),
interferes with the f6-rook’s control of c6, and fails to 1…Sf3!, which
protects d4 and cuts off the h1-bishop (2.Sc7+ Kxc6).
The third try, 1.Rd5? (2.Sd4 and 2.dxc4),
disables the h1-bishop’s control of c6, and Black defeats it by 1…Se6!,
guarding d4 and shutting off the f6-rook (2.dxc4+ Kxc6). |
125. Nils van Dijk
Die Schwalbe 1961
 
Mate in 2 |
The key is 1.Bd5!
(2.Sd4 and 2.dxc4), which interferes with the f5-rook’s line to c5, but
Black cannot exploit this with 1…Rd6 (to shut off the f8-bishop), because
the a6-knight controls c5 and White’s threats remain effective. The
two threats are separated by 1…Bxd5 2.Sd4 and 1.Rxd5 2.dxc4,
while 1…g3 stops both and is answered by 2.Sc7.
Have a go at solving Problem
126, which shows line play comparable to that in Problem 124, but
achieves it in a marvellously light setting.
126. Hendrik Prins
The Problemist
1984
Mate in 2
Solution
to Problem 126 (To display, hold down your mouse button and select the
text below)
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>
White’s a6-knight makes
two tries and the key,
aiming to mate on c6 or
b7. Each of the thematic
replies, 1…e5 and 1…f2,
opens a black line of
defence but also closes
another one, causing
Black to lose control of
a white bishop mate.
1.Sb4? (threat: 2.Sc6),
1…f2 2.Bb6, but 1…e5!
refutes because White’s
own self-interference
has disabled 2.Bc3.
1.Sac5? (2.Sb7) is
defeated by 1…f2!, when
2.Bb6 is obstructed. The
key 1.Sab8! (2.Sc6)
avoids closing any white
bishop line: 1…e5 2.Bc3,
and 1…f2 2.Bb6.>
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