Chess

OF ALL chess moves, with the possible exception of castling, pawn- promotion is the one which has taken longest to stabilise. The rules today are admirably clear:

"When a pawn reaches the rank furthest from its starting position it must be exchanged as part of the same move for a queen, rook, bishop or knight of the same colour. The player's choice is not restricted to pieces that have been captured previously..."

This, The Oxford Companion to Chess by David Hooper and Kenneth Whyld (inter alia) informs me, is essentially the same as the rules that applied in the first international tournament - London 1851. I turned for further elucidation to HJR Murray's definitive A History of Chess, which was originally published by Oxford University Press in 1913 (his father, Sir James AH Murray, was the first editor-in-chief of the Oxford English Dictionary).

From Murray I learnt that in the first edition of his L'Analyse du Jeu des Echecs (1749) the great Francois-Andre Danican Philidor (1726-95) deplored the custom of the French players who permitted a plurality of queens: indeed in earlier times this had even been seen as condoning adultery! But by the 1790 edition the present form had been adopted; it had been published in English by Arthur Saul in The Famous Game of Chesse- Play as early as 1614.

Ignoring the multifarious variants - the pawn must be exchanged for a piece already captured, and must otherwise await one; it can remain as a pawn for ever, etc - the modern variant gives rise to an awesomely complex problem theme, the "Babson task", which is named after the American composer Joseph Ney Babson.

Before I explain it, here is a quite magnificent setting - a mate in four. I would be tremendously impressed if any reader solved it, though of course, you're more than welcome to try; the beauty is in the effect of the problem, rather than in grappling with it.

Mate in four

LV Yarosh 1st prize Shakhmaty

vs SSSR 1983

The point of the Babson task is that Black should promote to all four pieces, in each case met by the matching white promotion.

After 1 a7!

if 1... axb1Q 2 axb8Q Qxb2 3 Qxb3 Qxa1 4 Rxf4 mate

or 1... axb1R 2 axb8R Rxb2 3 Rxb3 Kxc4 4 Qa4 mate

or 1... axb1B 2 axb8B Be4 3 Bxf4 and 4 Be3 or Be5 mate

or 1... axb1N 2 axb8N Nxd2 3 Qc1 Ne4 4 Nc6 mate.

There are also some (unthematic but necessary) sidelines, eg

1... Qxa8 2 Rxf4+ Qe4 3 a8Q Qxf4 4 Qd5 mate

or 1... Qxd8+ 2 Kg7! Qf8+ 3 Kxf8 axb1Q 4 d8Q mate.