Phases of Play
Peter's Problem World with FIDE Master of Chess
Composition
Peter Wong
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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The full solution of a
directmate problem often consists of more than the
key-move that solves it and the ensuing variations. In addition to
the
actual play that follows the key, there may be other
phases of play that are of
thematic interest, such as set play and try play.
Both types are distinct groups of potential
variations that tend to be considered naturally when solving a problem.
Furthermore, a problem may incorporate several phases of actual play, either
by using the device of twinning to create multiple positions for solving, or
simply by calling for more than one solution to be found.
Let us look at some
two-movers that clearly illustrate these types of extra play. |
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Set play is what would occur if the side that normally moves first could
miss a turn. So in a directmate, this phase refers to any
variations that are already prepared in the diagram, before White makes
the key.
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7. Henry D’O
Bernard
Chess Amateur
1918
Hon. Mention
  
 
  
Mate in 2 |
In
Problem 7, if Black were to begin, we find that every possible
move has been provided with a mating reply. The set play is
therefore: 1…f4 2.Qe4, 1…Rc5 2.Sxb4, and 1…R-else 2.Qb5.
A non-disruptive
move by White that preserves these set mates would solve the problem,
but none is available. Instead, the key 1.Sb8! (waiting),
by giving the black king a
flight square on c5 and putting an extra guard on c6, surprisingly
changes some of White’s mating responses: 1…f4 2.Qh5, and
1…Rc5 2.Qe6.
The other rook
variation is unchanged, 1…R-else 2.Qb5, and the king’s flight
leads to an added mate, 1…Kc5 2.Qc6. Set play is notable
thematically when it differs from the actual play, as here, giving rise
to
changed play. |
A first move by White
that nearly solves a directmate problem, but is defeated by only one black
defence, is called a
try. In notation, a try is signified by ‘?’, while the black move
that defeats it – known as the
refutation – is indicated by ‘!’.
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In 8, if the white king moves to
guard e4, 2.Rd6 will be threatened. The king has three ways to
approach e4, and two of them are thematic tries.
1.Kf3? makes the error of closing the
long diagonal, and it is refuted by 1…dxe6!, a
self-blocking defence that would have permitted 2.Bg2, if not for
the white king’s placement.
Likewise 1.Kd3? closes a vital line,
this time the d-file, so that 1…Rxc5! refutes, as White cannot take
advantage of this self-block with 2.Rd1.
The last way to attack e4 is the key:
1.Ke3! The black moves that previously worked as
refutations are now answered by the unhindered white mates, 1…dxe6
2.Bg2 and 1…Rxc5 2.Rd1.
One
by-play variation is 1…Rc6 2.Re5. |
8. David Shire
The Problemist
1990
 
 
Mate in 2 |
In the previous example,
the closely related tries (and their refutations) are sufficiently
interesting by themselves to represent a large part of the problem’s
content. Another type of tries creates even more content, by
introducing variations that are different from the actual play. Such
variations make up a phase that is called
try play or
virtual play.
Problem 9 neatly
illustrates this, along with the
focal theme.
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9. Norman
Macleod
Correspondence Chess
1962
5th Hon. Mention
 
Mate in 2 |
The first try is 1.Sd4? (waiting),
after which the black bishop is "focusing" on two possible mating
squares of the d4-knight, b3 and c6.
Upon moving, the bishop is forced to
"lose the focus" and unguard one of the two squares, e.g. 1…Be4
2.Sdb3, and 1…Be6 2.Sc6. Black cleverly defeats this try with
1…Bb7!, cutting off the rook on b8, so that 2.Sdb3 would not be mate.
Another try, 1.Sd6? (waiting), leads to
a different pair of knight mates following the bishop moves, 1…Be4
2.Sc4, and 1…Be6 2.Sdb7. But Black employs the same tactic as
before to refute: 1… Bb3! shuts off the other rook, so that 2.Sdb7
would only check.
Finally, the key 1.Sc3!
(waiting) controls a4 and frees the other knight to give a third pair
of mates, 1…Be4 2.Sb3, and 1…Be6 2.Sb7 (also 1…Bb3
2.Sxb3, and 1…Bb7 2.Sxb7). |
Three pairs of changed
mates are thus shown in this two-mover.
A
twin refers to a problem with multiple settings, each of which requiring
its own solution. The settings are produced by making small
adjustments to the initial diagram. Problem 10 demonstrates
such a twin with two parts. The diagram position is regarded as part
(a), and it is for solving as usual.
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The
stipulation then specifies that part (b) be formed by shifting the
black king to h5, and this position is to be solved anew.
Many methods of twinning are possible,
besides shifting a piece to another square, such as adding or removing
a piece, and replacing one piece with another.
Part (a) of this problem begins with
1.Be3!, which threatens 2.Sh4. Black has only two defences,
both self-blocks that provoke queen mates, 1…Rxg6 2.Qf3, and
1…Sxg6 2.Qh3.
Part (b) has the key 1.Bxf6!,
threatening 2.Sf4. The same defences by Black are playable, but
they lead to a special type of changed play called reciprocal
change. In this scheme, two white mating moves that work
against two defences respectively in one phase are effective again in
another phase, but these mates have to be swapped in dealing with the
two defences; so here 1…Rxg6 2.Qh3, and 1…Sxg6 2.Qf3. |
10. Josef
Retter
Hashavit Memorial Tourney
1982
3rd Prize
Mate in 2
(b) Kf5 to h5 |
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11. Barry
Barnes
British Chess Magazine
1970
Mate in 2
2 solutions |
Directmates that involve multiple solutions,
i.e. those necessitating more than one key to be found, are relatively
uncommon but quite legitimate.
Additional solutions are of course
distinguished from
cooks in that the former are intentional, and their presence in a
problem is always indicated as part of the stipulation.
The two solution phases in 11 feature
very harmonious strategy. The first key, 1.Qxc5! (waiting),
sacrifices a knight to the black king and activates the rook, 1…Kxe6
2.Qc6. And if 1…c3, a bishop line is opened, enabling 2.Qf2.
The second key, 1.Qxc4! (waiting),
sacrifices the other knight and activates the bishop, 1…Kxe5 2.Qd4.
And 1…cxb4 opens a rook line, which allows 2.Qf1. |
Problem 12 is for you to solve. Look out for two prominent defences
that are dealt with differently in three phases (set, try, and actual play).
12. Cornelis Goldschmeding
Problem
1957
Mate in 2
Solution
to Problem 12 (To display, hold down your mouse button and select the
text below)
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>The two thematic
defences are the rook
checks on b7 and c6. Set
play: 1…Rb7+ 2.cxb7, and
1…Rxc6+ 2.Qxc6. Try
play: 1.Qa1? (threat:
2.S-any), 1…Rb7+ 2.Sxb7,
and 1…Rxc6+ 2.Sxc6, but
1…Rxb5! refutes. Actual
play: 1.Qf1!
(threat: 2.Rxb6),
1…Rb7+ 2.Rxb7,
1…Rxc6+
2.Rxc6, and
1…Rxb5
2.Qxb5.>
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Chess Composition
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