BCPS

‘White to play and checkmate in two moves’. You wouldn't miss such a short combination in a game. Surely chess problems stipulating ‘White to play and mate in 2’ (or, more usually, #2) are not that simple? No, they are not! Look at just some of the basic types of ‘two-movers’, and decide for yourself. Some amazing ideas that might never have occurred to you in over-the-board play will be revealed:

(1) Threat Problems

The obvious way to overwhelm Black is to threaten an irrefutable checkmate. But is it an obvious key-move, the white King's advance into a barrage of checks?

G Guidelli 2nd Prize, L'Eco degli Scacchi, 1916-1917 Mate in 2

1.Kf7! (threat 2.Qb8#) 1...Ke5 2.Sc4; 1...e5+ 2.S7d5; 1...Be5+ 2.S7f5; 1...Bxe7+ 2.Bxf4; 1...B else+ 2.S3f5.

(2) Waiting Problems

Sometimes, examination of the ‘White to play and mate in 2’ position reveals that every Black move (or almost every black move) is set with a mating reply – Zugzwang. Is there a White first move that provides for everything and waits for Black to commit himself? Solvers found the key-move in David Shire's problem tricky to find:

D. J. Shire The Problemist Supplement, 1997 Mate in 2

1.Kh2! (Waiting) 1...Rd2+ 2.Sxd2; 1...Rxf3 2.Qe4; 1...Rd4 2.Se5; 1...Re3 2.Sd2; 1...R else 2.Qxc3; 1...Sxa4 2.Qxa4; 1...S else 2.Qxa2; 1...B any 2.Q(x)b3. Not, for example, 1.Kg3/h3? Re3!

(3) Mutates

Supposing there was no ‘simple’ waiting move to preserve the mates provided (set) for all Black's moves, as in David Shire's problem? Before the key-move is made in Spiric's problem, the solver sees the set mates following the black moves 1...Kd5, 1...d5 and 1...B any. But there is no waiting move that preserves this state of affairs. Imagine the wonder of (eventually) finding the key move 1.Qh6! Waiting. Now, we see some changed mates following the black moves. The white Queen has craftily ambushed herself behind 3 men!

I. Spiric The Problemist, 2002 Mate in 2

Set play: Actual play: 1.Qh6! Waiting. 1...Kd5 2.Qf3; 1...Kd5 2.Qh1; 1...d5 2.Qxc7; 1...d5 2.Se5; 1...B any 2.S(x)e7. 1...B any 2.S(x)e7.

(4) Threat Problems with Set Play + Changed Play

Most compositions which change set mates are not in the Waiting (or Block) form of Spiric's Mutate, but in the freer form of a key-move making a second move threat. Prominent black moves set with mates in Swane's problem catch the solver's attention, and make him reluctant to abandon them in his search for a solution. It's more than likely that the solver will see first the set play. How long would it take him to find the key-move 1.Se4! (threat 2.Qxb3#)? from which three changed mates result!

J. A. W. Swane 1st Prize, Magasinet, 1952 Mate in 2

Actual play: Set play: 1.Se4! (threat 2.Qxb3#) 1...Rxd3 2.Qa4; 1...Rxd3 2.Qxc5; 1...S2xd3 2.Re4; 1...S2xd3 2.Sd6; 1...S4xd3 2.Bd5. 1...S4xd3 2.Sd2;   1...Kxd3 2.Qxb3.

(5) Try Play Problems

Chess composition – for long with the post-key play and set-play/post-key combinations of the first four problems – gained another dimension with the studied introduction by composers of try play. Which of the likely moves 1.Kxd5 or 1.Kxd7 should White play in the following problem? Two parallel lines of play are woven into one problem.

B. P. Barnes The Problemist, 2002 Mate in 2

Try play: 1.Kxd5? Waiting Actual play: 1.Kxd7! Waiting 1...b6/b5 2.Rxd7; 1...b6/b5 2.Kd6; 1...c3 2.Kd6; 1...c3 2.Bxd5; 1...d6 2.Rxb7; 1...d4 2.Bxc4; 1...Sxf6+ 2.Qxf6; 1..Sxf6+ 2.Qxf6; 1...S else 2.R(x)f8; 1...S else 2.R(x)f8; 1...gxh5 2.Qg7; 1...gxh5 2.Qg5; but there is no mate for 1...e4! 1...e4 2.Qxd5;.

(6) Set Play + Try Play + Changed Play Problems

Ever more is packed into the ‘modern’ two-move chess problem. It is unlikely that the solver will miss the set mates in Slesarenko's problem. You might think you have solved the problem and changed the mates after the black King flights with 1.Qa1? but 1...b5 (freeing c6) refutes the try. The key is 1.Qh7! (2.Qe4#) with changed mates and some lovely by-play. To give you a taste of chess problem jargon, this is a 3 (phases of play) × 2 (mates changed each time) Zagoruiko, named after a Russian pioneer of the 1940s.

A. Slesarenko The Problemist, 2002 Mate in 2

Set play: Try play: 1.Qa1? Actual play: 1.Qh7! (threat 2.Qe4#) 1...Kc4 2.Se5; (threat 2.Qxa2#) 1...Kc4 2.Sxb6; 1...Ke6 2.Sd4 1...Kc4 2.Qd4; 1...Ke6 2.Qf5;   1...Ke6 2.Qe5; By-play   but 1...b5 1...g6 2.Qxf7;   (freeing c6) 1...f5 2.Qg8.   refutes the try.

(7) Bizarre Problems

What does an out-and-out chess player make of Ian Shanahan's weird problem? There are three threatened mates, ABC. The seven different moves at Black's disposal (including underpromotions of the black Pawn) lead to every combination of ABC. Is combinative separation of threats too outlandish for you? Mathematics and chess are bedfellows indeed!

I. Shanahan The Problemist Supplement, 2001 Mate in 2

Key 1.Bh5! (threats 2.Qxe3 A and 2.Qg4 B and 2.Qf3 C) 1...Rh1 2.ABC; 1...g1S 2.AB; 1...g1R 2.AC; 1...g1B 2.BC; 1...Ke4 2.A; 1...Kg3 2.B; 1...g1Q 2.C.