Win/Draw/Loss tablebase value

A tablebase is a precomputed database of endgames with few pieces. Instead of estimating a position, it stores the correct outcome under defined rules. A WDL value, short for win, draw, loss, answers whether the position is a win, draw, or loss.

The result is stated from the perspective of the side to move. If a tablebase query returns a win, that side can force the winning outcome against every permitted defense. Changing whose turn it is can therefore change the category even when all pieces remain on the same squares.

Syzygy tablebases refine the three basic outcomes into five values. In addition to win, draw, and loss, they distinguish a cursed win, which may not be converted before the fifty-move rule intervenes, and a blessed loss, where that rule may allow the losing side to save a draw. The rule limits an extended phase without a capture or pawn move.

WDL does not say how many moves remain, which route is easiest, or which move best preserves progress toward the goal. It is also not an approximate pawn-based evaluation. It is an exact classification within the positions and conditions supported by the tablebase. A chess engine, a program that analyzes positions, may combine it with other information when choosing among several moves that share the same outcome.