Minimax
Minimax is a decision method in which one side tries to maximize the evaluation while the opponent tries to minimize it, forming the basis of how traditional chess engines choose moves.
Also called: minimax search
Minimax is the core idea behind classic chess engines. Picture a tree of positions. At each level, one player picks the move that gives the highest score for themselves, and the other picks the move that gives the lowest score for the first player. The engine works backwards from the evaluations at the bottom of the tree and chooses the move at the top that gives the best result against the strongest reply.
In plain terms, minimax assumes the opponent will always find your best response. That makes it a cautious way to choose moves, since it prepares for the worst case rather than hoping for a mistake. In practice, engines use alpha-beta pruning to avoid checking every branch, which keeps the idea practical.
The same thinking helps human players. When comparing candidate moves, imagine your opponent’s best answer to each one, and choose the move whose worst case is the most acceptable. This is often more reliable than choosing the move that looks best if your opponent cooperates. Calculating forcing lines with that mindset reduces the chance of overlooking a strong reply.
A neighboring idea is Principal variation. The principal variation is the line of best play for both sides that an engine has found, shown as a sequence of moves and tied to the evaluation it reports.
Compare it with Search depth. Search depth is how many moves ahead an engine has looked in a position, counted in half-moves called plies, and deeper searches generally give more reliable evaluations and moves.
An engine can tell you what "Minimax" means for a position, but not which mistakes you keep making; a first lesson with George Li reviews your games and finds those.
Related terms
Alpha-beta pruning is a search technique that skips branches of the move tree that cannot change the minimax result, letting engines look much deeper using the same amount of computing time.
Search depth is how many moves ahead an engine has looked in a position, counted in half-moves called plies, and deeper searches generally give more reliable evaluations and moves.
A chess engine is a computer program that searches positions and evaluates moves, usually playing and analyzing far stronger than any human, and it is used for analysis, preparation and play against a machine.
An evaluation is a numerical judgment of who stands better in a position, usually given in pawns from White’s point of view, where positive favors White and negative favors Black.
The principal variation is the line of best play for both sides that an engine has found, shown as a sequence of moves and tied to the evaluation it reports.
Stockfish is a free, open-source chess engine developed by a worldwide community, widely regarded as one of the strongest engines available and used by many analysis websites and apps.
Guides that go further
What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.
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Published rates for private, group and subscription chess coaching, with the source and the date of each.
A game review, a read on your level and a written study plan from George Li.
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A first lesson starts with your games: George reviews them and builds a study plan around what he finds.