Problem World > No.2
Phases of Play by Peter Wong

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.

 7. Henry D’O Bernard Chess Amateur 1918 Hon. Mention Mate in 2

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. 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.

 8. David Shire The Problemist 1990 Mate in 2

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 ‘!’. 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.

 9. Norman Macleod Correspondence Chess 1962 5th Hon. Mention 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. 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.

 10. Josef Retter Hashavit Memorial Tourney 1982 3rd Prize Mate in 2 (b) Kf5 to h5

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. 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.

 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.

 12. Cornelis Goldschmeding Problem 1957 Mate in 2

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).

#### Problem 12 solution (To display, select or highlight the text below.)

> 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. <