A classic retractor

Last April we posted a report on a new proposal by Bobby Fischer to modify the rules of chess. Apparently in order to eliminate the "unbearable preponderance of tactics in chess" the ex world champion submitted a rule modification to FIDE that allowed players to take back moves and play something else instead. At the time we wrote: "The new 'Fischer move', (which is also referred to as a 'retractor') does not change the original flavour of the game – in fact many believe it actually reflects it more completely than the rules practised in tournaments today."

Unfortunately it turned out that the whole report had been a cruel hoax, perpetrated by an evil prankster in the ChessBase team. Apparently he was practising a pagan ritual know as "April Fool".

So the retractor was not introduced into current-day chess, and the "touch-move" rule is still strictly enforced. However there is an area of the game in which you can – in fact must – take back moves and execute an alternative line instead. Here's a simple example:

B. Sommer, Deutsches Wochenschach 1910

White takes back his last move and mates in one

To clarify: in the above position White has just executed a move. He takes back this moves and plays instead a different move, one that immediately mates the black king. Try to solve it yourself. The answer is given below.

A good place to find problems of the unorthodox kind is Tim Krabbé's Chess Curiosity page. That is where I found the following charming retractor, specifically in Tim's "Chess Diary" (entry #204).

M. Adabashev, "64" 1938

White takes back his last move, and instead mates in one

This is, incredibly, a quadruplet retractor, i.e. it has four parts:

A: diagram position above
B: move all pieces one rank up
C: move all pieces two ranks up
D: move all pieces three ranks up

Each solution is different and unique. To make it easier for you to solve here are the problems B–D as separate diagrams:

Puzzle contest

Have you finished solving our Christmas Puzzle Contest? If you go to work on the four-part Adabashev problem you can once again win a prize, an autographed copy of one of our top programs. The solutions must be received before the 15th of March 2003. Please do not send multiple emails or attached Word documents.

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Solutions to the Adabashev puzzle and prize winner

Solution to the problem by B. Sommer: White takes back the move 1.exf6 e.p. (Black previous move was ...f7-f5) and instead plays 1.e8Q mate.

Frederic Friedel

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