Babson task


The Babson task is a particular type of chess problem, namely, a directmate with the following properties:
  1. White makes the only move that forces checkmate in the stipulated number of moves.
  2. Black's defences include the promotion of a certain pawn, to either a knight, a bishop, a rook, or a queen.
  3. If Black promotes, then White must promote a pawn to the same piece that Black just promoted to - this is the only way to force checkmate within the stipulated number of moves.
The task is named after the first person to speculate about the existence of such a chess problem, Joseph Ney Babson, in 1884.
It is regarded as one of the greatest challenges for a composer of chess problems to devise a satisfying Babson task problem, and for almost a century, it was unknown whether the task was possible.
The Babson task is a special form of Allumwandlung, a chess problem in which the solution contains promotions to each of the four possible pieces. Such problems were already known when Babson formulated his task.

Forerunners of the Babson task

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.
The key move in Bettmann's problem 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 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 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 :
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 fewer than 30 men are on the board. It also has six promoted pieces in the initial position, which is in any case illegal—it could not be reached in the course of a game. 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:
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 hxg3+ 2.Kh3 Bxb8 3.Qxc2 and mate next move. Yarosh then substituted a knight is on that square; now 1.axb8=N fails to 1...Nf3+ 2.Bxf3 Bxb8 3.Qxc2 Bxg3+ and White is too late. 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:
The key here is non-capturing and also thematic : 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

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:
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.
The key is 1.Nxb6. The thematic defences are: