Elimination method

The elimination method begins with several options and removes those that fail a minimum requirement. In chess, that requirement may be surviving a threat, avoiding a concrete sequence that wins a piece or pawn, preserving an acceptable position, or meeting the practical purpose of the move.

A rejection should rest on a reason that can be checked. A candidate may be eliminated because it is illegal, allows a forcing reply that wins a piece or pawn, exposes the king, ignores an urgent threat, or leads to an outcome clearly worse than another option. Merely finding a move unusual or unattractive is not enough.

The method reduces the number of branches, the continuations growing from each option, that need deep calculation and is particularly useful when time is limited. However, being the only surviving move does not prove that a move is good. The original candidate list may be incomplete, and the remaining option still needs a basic safety check.

In practice it is often combined with the candidate-move method, which creates the initial list of options, and the comparison method, which ranks the resulting positions. Clearly unacceptable options are removed first; the viable survivors are then compared.