Babson task

The Babson task is a kind of chess problem of the form "White to move and mate Black in n moves against any defence" (a directmate) with the following play:

1. White makes his first move.
2. Black defends by promoting a pawn to a queen, rook, bishop or knight.
3. White responds by also promoting a pawn to queen, rook, bishop or knight respectively. That is, if Black promoted to rook, so does White, if Black promoted to knight, so does White and so on. No other promotion (or any other move) leads to a forced mate in the stipulated number of moves.

The task is named after the first person to speculate about the possibility of such a problem, Joseph Ney Babson. It is regarded as one of the greatest challenges for a composer of chess problems to devise a satisfying Babson task problem, and for around half a century the task was considered to be near-impossible in directmate form.

Technically, the task can be regarded as a form of Allumwandlung with corresponding promotions by Black and White. An Allumwandlung is a problem which contains, at some point in the solution, promotions to each of the four possible pieces - such problems had already been composed before Babson devised his task.

Forerunners of the Babson task

Wolfgang Pauly, 1912

This 1912 problem by Wolfgang Pauly is, as it were, a three-quarter Babson task - three of Black's promotions are matched by White. White to move and mate in four:

The key is 1.b3, after which there are the following lines:

This is not a full Babson, however, because 1...a1=B 2.f8=B does not work - White must instead play 2.f8=Q, with similar play to above.

Selfmate Babsons

The earliest Babson tasks are all in the form of a selfmate - this is where White, moving first, must force Black to mate him against his will within a specified number of moves. In 1914, Babson himself published a selfmate which achieved the task, although three different white pawns shared the promotions. The first problem in which a single black and single white pawn were involved in the promotions was by Henry Wald Bettmann, and won 1st prize in the Babson Task Tourney 1925-26.

Henry Wald Bettmann
1st Prize, 1925-26 Babson Task Tourney

The key move in Bettmann's problem (left) is 1.a8=B, after which the play goes:

A number of other selfmate Babson tasks with one pawn of each colour doing all the promotions followed this one.

Directmate Babsons

Composing a Babson task problem in directmate form (where White moves first, and must checkmate Black against any defence within a stipulated number of moves) was thought so difficult that very little effort was put into solving it until the 1960s, when Pierre Drumare began his work on the problem which occupied him for the next twenty years or so. He managed to compose a Babson task problem using nightriders (a fairy piece which moves like a knight, but can make any number of knight-like moves in the same direction in one go) instead of knights, but found it hard to devise one using normal pieces - because of their limited range, it is difficult to justify White promoting to a knight because of Black promoting to one way over the other side of the board.

When Drumare did eventually succeed using conventional pieces in 1980, the result was regarded as highly unsatisfactory, even by Drumare himself. It is a mate in five (first published Memorial Seneca, 1980):

Pierre Drumare
Memorial Camil Seneca, 1980

The key is 1.Rf2, after which Black captures on b1 are answered by white captures on g8.

Efficiency in chess problems is considered a great boon, but Drumare's attempt is very inefficient - no less than 30 men are on the board. It also has six promoted pieces in the initial position (even a single promoted piece is considered something of a "cheat" in chess problems), which is in any case illegal - it could not be reached in the course of a game (one of the white f-pawns must have made a capture, and the white and black b- and c-pawns must have made two captures between them, making three in total, yet only two units are missing from the board). Despite all these flaws, it is the first complete Babson task.

In 1982, two years after composing this problem, Drumare gave up, saying that the Babson task would never be satisfactorily solved.

The following year, Leonid Yarosh, a football coach from Kazan then virtually unknown as a problem composer, came up with a much better Babson task problem than Drumare's - the position is legal, it is much simpler than Drumare's problem, and there are no promoted pieces on board. First published in March 1983 in the famous Russian chess magazine Shakhmaty v SSSR, this is generally thought of as the first satisfactory solution of the Babson task. Drumare himself had high praise for the problem. It is a mate in four:

Leonid Yarosh
Shakhmaty v SSSR, March 1983

The key is 1.Rxh4, and the main lines are:

Black has more options for its first move, of course, but these are not part of the Babson theme. They also result in checkmate on the fourth move.

However, Yarosh's problem has a small flaw - the key is a capture, something which is generally frowned upon in problems. Also, when first presented the black piece at h4 was a pawn, but a computer discovered an additional solution by 1.axb8=N in that construction which is not there when a knight is substituted on that square. Nevertheless, when Dutch author Tim Krabbé saw this version in the Soviet publication 64, he records that the realisation that somebody had at last solved the Babson task had the effect upon him as if he had "... opened a newspaper and seen the headline 'Purpose Of Life Discovered'."

Yarosh continued to work on the problem and in August 1983 his improved version with a non-capturing key appeared in Shakhmaty v SSSR. It is generally considered one of the greatest chess problems ever composed. Again, mate in four:

Leonid Yarosh
Shakhmaty v SSSR, August 1983

The key here is non-capturing and also thematic (that is, it is logically related to the rest of the solution): 1.a7. The variations are largely the same as in the original:

Yarosh composed a completely different Babson task problem later in 1983 and another in 1986. Several other Babsons have since been composed by other authors.

The cyclic Babson

Peter Hoffmann, Die Schwalbe, 2003

In the August 2003 issue of the German problem magazine Die Schwalbe, the problem to the right, a mate in four by Peter Hoffmann appeared. Hoffmann had previously published a number of conventional directmate Babsons, but this one is significant as it is the first cyclic Babson: rather than black promotions being matched by White, they are related in cyclic form: Black promoting to a queen means White must promote to a bishop, Black promoting to a bishop means White must promote to a rook, Black promoting to a rook means White must promote to a knight, and Black promoting to a knight means White must promote to a queen.

The key is 1.Nxe6, threatening 2.hxg8=Q and 3.Qf7#. The thematic defences are:

• 1...d1=Q 2.hxg8=B (2.hxg8=Q? Qd7+ 3.Bxd7 stalemate), threatening 3.c4+ Q-moves 4.BxQ#
  • 2...Qd7+ 3.Bxd7 Kxg6 4.Rxh6#
  • 2...Qxc1 3.Rxg5 (threat: 4.Rf5#) hxg5 4.Qh8#
• 1...d1=B 2.hxg8=R (2.hxg8=Q? stalemate) Kxe6 3.Rd8 3.Kf6 Rd6#
• 1...d1=R 2.hxg8=N (2.hxg8=Q? Rd4+ 3.c4 stalemate) Kxe6 3.Qxe2+ K-moves 4.Qe5#
• 1...d1=N 2.hxg8=Q Nxb2+ 3.Kb5(Bxb2) and 4.Qf7#

There are also a number of sidelines.

As with Drumare's original Babson task, the problem uses promoted pieces and has a capturing key, but it is nonetheless remarkable for being the first published cyclic Babson.

In the September 2005 issue of Schach, the first cyclic Babson without promoted pieces in the initial position was published. Again, the composer was Peter Hoffmann.