Nakamura and Lc0 competed in a 3+2 blitz format (3 minutes per side, plus 2 seconds increment per move). Lc0 played with a one-rook handicap, while the starting positions of the other pieces remained standard. Nakamura, the Japanese-American grandmaster, chose his color.

In chess, the queen is the most powerful piece, valued at 9 points. A rook is worth 4.5 to 5 points. Bishops and knights are both worth 3 points, while a pawn is worth 1. The rook handicap gave Nakamura a +5 point advantage from the start.

A meme of Nakamura (right) playing against the supercomputer. Photo: GMHikaru

A meme of Nakamura (right) playing against the supercomputer. Photo: GMHikaru

Nakamura began the match with an aggressive, attacking style but lost the first 4 games. In each loss, he made critical errors in winning positions. Lc0, on the other hand, made no mistakes, capitalizing on every one of Nakamura's slips.

The next 3 games were drawn. From this point, the 37-year-old grandmaster began to adapt his strategy. He aimed to exchange queens early and simplify the position by quickly trading pieces, leading to an endgame. With fewer pieces on the board, the position would be less complex, reducing the likelihood of errors.

However, it wasn't until the 12th game that Nakamura secured his first victory, bringing the score to 3.5-8.5. In this game, he achieved a significant advantage in the middlegame, being up a rook and 3 pawns. He then sacrificed his queen to transition into a rook and 2 pawns versus rook endgame, a basic endgame scenario where even an amateur player could potentially defeat a supercomputer.

The final score was 9.5-4.5 in favor of the supercomputer. Had the match continued, Nakamura might have narrowed the gap. His revised opening strategy yielded better results compared to the beginning of the match.

Throughout the match, Nakamura repeatedly expressed admiration for Lc0's skill in finding the necessary moves. During the hour-long contest, he exclaimed "insane" 13 times and "ridiculous" 11 times, praising the supercomputer. In contrast, he admitted to "stupid mistakes" 26 times regarding his own play.

Nakamura is currently ranked second in the world in classical chess, 10th in rapid chess, and second in blitz chess. His classical rating is 2,807.

Lc0 is a free, open-source chess engine based on Google's AlphaZero. Gary Linscott, a computer scientist, initiated Lc0 and also founded another supercomputer, Stockfish. The Elo ratings of both Lc0 and Stockfish are estimated to exceed 3,600.

Xuan Binh