Some years ago I was inspired by discussion with a friend, Nicholas, to write a chess problem in which the difficulty was not to identify the best line of play but to identify what piece is missing from the position and where. This grew to be a series of problems, which having gone through a few rounds of play testing and editing1There may still be errors… I share here.
In each problem, a valid chess position is shown, and its valuation. However, the white king is invisible. Determine the location of the white king such that the chess position is valid and has the given valuation. The valuation of a position assumes, as always, that both sides play perfectly.
Note that one or more of these problems have elements of retrograde analysis. A valid chess position is one that is reachable from the standard starting position with a series of legal moves. As is conventional for chess composition, castling is assumed to be legal and en passant to be illegal in cases where there is ambiguity, i.e., unless otherwise is specified or can be proven.2If that sounds contrived, consider that someone once wrote a series of retrograde chess problems centered on the following gimmick: “Sometimes it is possible to prove that if castling is possible, then the previous move must have been a double step of a pawn, making an en passant capture legal. In this case, the en passant capture is made, then its legality is proved a posteriori; this is accomplished by castling. In some such problems, Black’s defence consists of trying to prevent White from castling, rendering the initial en passant capture illegal. […] This composition was highly controversial […] Amid the controversy, it was overlooked that the win is not clear in the final position”.
No chess principles were involved in setting these problems and none are required to solve them.
This is the first problem I wrote.
I really enjoy the visual appearance of this position. This problem illustrates an important concept which will recur. Even though the position is symmetric, there exists a unique solution.
Hints and solutions to each problem will be given in the following posting in this series.
Follow RSS/Atom feed for updates.