3) How it figured out how to Evaluate a Board
Traditional chess engines (like older versions of Stockfish) were explicitly programmed by humans to evaluate positions using hardcoded values: a pawn is 1 point, a knight is 3 points, king safety has a specific formula, etc. [
1]
- AlphaZero’s approach: It was given a neural network with a "value head". At first, its board evaluations were completely random. However, as it played millions of games against itself, it looked at the final outcomes (win, loss, or draw) and worked backward to adjust its internal math. [1, 2, 3, 4]
- The result: It independently discovered nuanced positional concepts—like piece coordination, king safety, and sacrificing material for long-term activity—achieving a deep, machine-learned "intuition" for board evaluation without human assistance. [1, 2]
4) How it figured out how to Calculate Future Moves
Traditional engines use a "brute-force" approach (like Minimax search with Alpha-Beta pruning) to calculate tens of millions of possible move combinations per second. [
1,
2]
- AlphaZero’s approach: It was programmed with a Monte Carlo Tree Search (MCTS) algorithm. Instead of checking every legal response, MCTS relies on the neural network's "policy head" (which predicts what the most promising moves are) to act as a filter. [1, 2, 3, 4]
- The result: AlphaZero calculated far fewer positions than traditional engines (about 60,000 positions per second compared to Stockfish's 60 million). However, because its neural network told it which lines were actually worth looking into, it calculated much more deeply and intelligently along the most critical paths. [1, 2, 3]
5) How it figured out how to Choose the Best Option
AlphaZero was never programmed with "opening books" or an endgame database. [
1,
2]
- AlphaZero’s approach: During an actual game, AlphaZero combines its calculation (MCTS) and its intuition (the neural network). The search explores a tree of future possibilities, uses the evaluation network to score how those futures look, and then counts which starting move consistently leads to the highest probability of winning. [1, 2, 3]
- The result: It selects the move that maximizes its chances of victory based entirely on its own self-taught logic, routinely playing creative, highly aggressive strategies that revolutionized how grandmasters understand chess. [1, 2]