Soundness

A chess composition is a position created by an author with a specific task. Its soundness answers a precise question: does the position do exactly what its stipulation, the task written beside the diagram, claims? Soundness does not measure beauty, originality, or difficulty. It checks that the announced task can be achieved as intended and that no improper alternative exists.

Defects a soundness check looks for

• A cook is an unintended solution that begins with a different first move from the author's solution.
• A short solution fulfills the task in fewer moves than required.
• A problem has no solution when the announced task cannot be fulfilled.
• A dual occurs when, after the first move, more than one continuation can fulfill the task. How serious it is depends on the genre and where it appears.

Some compositions explicitly require several solutions, phases, meaning distinct sections of content, or continuations. That multiplicity is not a defect because it belongs to the stated task. Testing soundness means comparing all legal play with what the author declared, rather than confirming one plausible line.

A chess engine, a program that calculates moves, can help uncover alternative solutions or missed defenses. It must still be configured for the exact genre, pieces, and conditions, because soundness is a logical property of the composition and its rules.