So how strong is AlphaGo? To answer this question, we played a
tournament between AlphaGo and the best of the rest - the top Go
programs at the forefront of A.I. research. Using a single
machine, AlphaGo won all but one of its 500 games against these
programs. In fact, AlphaGo even beat those programs after giving
them 4 free moves headstart at the beginning of each game. A
high-performance version of AlphaGo, distributed across many
machines, was even stronger.
It seemed that AlphaGo was ready for a greater challenge. So we
invited the reigning 3-time European Go champion Fan Hui — an
elite professional player who has devoted his life to Go since the
age of 12 — to our London office for a challenge match. The match
was played behind closed doors between October 5-9 last year.
AlphaGo won by 5 games to 0 — the first time a computer program
has ever beaten a professional Go player.