What does solved mean?
Solving a game can mean three things, from the least to the most.
| Knowing the answer | You know how the game ends from the start if both sides play perfectly: a win for the first player, a loss, or a draw. |
|---|---|
| Being able to show it | You have a way of playing from the start that always gets that result, whatever the opponent does. |
| Knowing everything | You know the best move in every legal position. |
Chess isn't solved in any of these senses.
Games that are solved
Connect Four was solved in 1988, by James D. Allen and, fifteen days later, Victor Allis, independently. The first player can always win.
Checkers was solved in 2007 by Jonathan Schaeffer's research team. With perfect play from both sides, it's a draw. The game is roughly a million times more complex than Connect Four, the researchers wrote. Chess is far more complex than that: there are about 4.8 × 1044 possible positions, according to an estimate from 2022.
The endgames that are solved
What is solved in chess is the endgames with few pieces left. There, computers know the best move in every position. The kings count.
| Pieces on the board | Solved |
|---|---|
| 6 | every position, 2005 |
| 7 | almost all in 2012, at Moscow State University; all in 2018 |
| 8 | work in progress |
There are surprises in there. When the seven-piece positions were finished in 2012, one was found in which the winning side needs 549 moves to deliver mate. Among eight-piece positions where each side has one pawn and the two pawns block each other, Marc Bourzutschky found one in 2021 in which White needs at least 584 moves to mate or reach a won seven-piece ending.
You can learn the simplest endgames yourself, under endgames.
And computers?
Computers play far stronger than humans, but they haven't solved the game. They calculate and judge positions, which isn't the same as knowing the answer. More under Can a computer beat the world champion?
Sources
- Wikipedia: Solving chess; Solved game; Endgame tablebase; Connect Four
- John Tromp: Connect-4 (on Allen's and Allis's solutions in 1988)
- J. Schaeffer et al.: Checkers Is Solved, Science 317 (2007), the abstract on PubMed
- Chessprogramming Wiki: Nalimov Tablebases; Syzygy Bases
- ChessBase, May 11, 2022: 8-piece endgame tablebases, first findings
- Marc Bourzutschky: 8-men Tablebase explorations, "opposing 1 pawn" endgames (ARVES, 2021)
- John Tromp: ChessPositionRanking (the number of positions)
The facts on this page come from the sources above and, where possible, were checked across several sources. Where the sources disagree, we say less or say what each one says. A number that is an estimate says whose it is, and a counted number comes with its date.
Updated November 14, 2026