Try

In classical problem terminology, a try is a White first move that appears to solve the task but fails to one Black defense. That unique defense is called the refutation. Because Black has it, the line is not the actual solution.

Not every failed attempt made by a solver is a try. The term is normally reserved for a deliberately constructed false solution with thematic relevance. The variations following a try form a virtual phase, meaning analyzed content that is not the actual solution, and can be compared with set play, the replies already prepared in the initial position.

The difference from the key, the first move of the actual solution, is decisive: the key survives every defense and solves the problem, while the try has exactly the weakness that lets Black refute it. In inverse problems such as a selfmate, where White forces Black to mate the white king, tries can also appear under the same idea of a thematic false key.