Updated, March 15: And finally, to round out the series, the AlphaGo AI has taken the last game against Lee Se-dol to end the match 4-1.

DeepMind's Demis Hassabis said that AlphaGo made an "initial big mistake," but managed a "mind-blowing" comeback. Lee, at the post-game press conference, said the match had been very difficult from a psychological perspective.

We can probably now conclude that AlphaGo is better than any human player of Go. Or, at the very least, it definitely will be after DeepMind makes a few tweaks following the match.

The final match was a long, drawn-out affair. You can watch it below:

Updated, March 13: Somewhat surprisingly, Lee Se-dol has finally won a game against AlphaGo, taking the current match score to 1-3. With only one game left to be played, Lee can't win the match, but at least Lee has shown there's hope for humanity yet.

Demis Hassabis, chief of the DeepMind group that created AlphaGo, said during the game that the Go-playing AI made a mistake on move 79, but didn't realise until move 87. That mistake was seemingly enough for Lee to eke out a victory.

At the post-game press conference, Lee was greeted by a massive round of applause. "I've never been congratulated so much just because I won one game," said Lee.

"Lee Se-dol is an incredible player and he was too strong for AlphaGo today," said Hassabis at the press conference. "For us this loss is very valuable. We're not sure what happened yet."

The final game of the series begins at 4am GMT on March 15 (00:01am EST). You can watch AlphaGo's first professional loss below:

Original story

Late on Tuesday night, Google's DeepMind AI group began its show down against one of the world's best human Go players, Lee Se-dol of South Korea. Now by the end of the week, the search giant's robotic hivemind has defeated humanity 3-0 in a clean sweep.

The matchup was best of five games in total between AlphaGo (DeepMind's Go-playing software) and Lee, all played at the Four Seasons hotel in Seoul. The winner of the series receives a $1 million (£700,000) prize—so with DeepMind winning, it will donate the proceeds to charity. Lee, by virtue of being a champion prizefighter who has spent most of his life honing his Go skills, still received about £100,000 just for turning up.

Match one

In the very tense initial game seen above, AlphaGo defeated Lee Se-dol. Lee, who is 32, was confident heading into the match that he could beat AlphaGo either 5-0 or 4-1 this time around. “I have heard that Google DeepMind’s AI is surprisingly strong and getting stronger, but I am confident that I can win at least this time," Lee said in statement on February 4. In a follow-up interview with the Associated Press on February 22, he added: "But if artificial intelligence continues to advance, in a year or two years, it will be really hard to guess the results."

Speaking after the first game, Lee wasn't shaken and still felt he could win. However, he admitted to being "very surprised... I didn't expect to lose. I didn't think AlphaGo would play the game in such a perfect manner."

Match two

AlphaGo defeated Lee Se-dol again in the second of five games, see above, to take the tally to 2-0.

"Yesterday I was surprised, but today it's more than that—I am quite speechless," said Lee Se-dol at the post-game press conference. "I have to say, if you look at how the game was played, I admit that it was a very clear loss on my part. From the very beginning of the game ... there was not a moment in time where I felt that that I was leading."

DeepMind's Demis Hassabis was also "speechless," adding that "we're very pleased that AlphaGo played some quite surprising and beautiful moves, according to the commentators, which was amazing to see."

During the Q&A section of the press conference, when Lee Se-dol was asked whether AlphaGo had any weaknesses or not, he replied with a smile. "Well I guess I lost the game because I wasn't able to find a weakness."

Hassabis said that's why the match with Lee Se-dol is so useful—to find out what AlphaGo's weaknesses are.

Match three

And to start this weekend, AlphaGo won its third straight game against Lee Se-dol, thus ending the match. The last two games will still be played, however, with the fourth game starting at 4am GMT (11pm EST) tonight and the final showdown happening on Monday night. Lee still has a shot at earning £15,000 for each game that he wins.

At the post-game press conference following his third loss, Lee apologised for not being able to beat AlphaGo and asked people to continue watching the rest of the series.

The third game was notable because AlphaGo had to engage with Lee in a number of ko fights—a scenario that had not occurred in the first two games. There had been some speculation that ko were one of AlphaGo's weaknesses, but that's clearly not the case.

Back in October, AlphaGo beat three-time European champion Fan Hui 5-0. The artificial intelligence community was shocked by the result. Go includes about 1,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000 possible positions to choose from, and the game can't be won with "simple" brute-force search techniques (with current amounts of processing power, anyway).

Instead, AlphaGo uses a novel mix of deep neural network machine learning and tree search techniques. Without getting into the complexities of it, DeepMind taught AlphaGo how to play the game by watching human Go masters play. The system then honed its strategy by pitching instances of AlphaGo against each other in a process known as reinforcement learning. Thousands (or millions?) of iterations later (with a bit of AI secret sauce), and AlphaGo was ready to, er, go.

Updated, March 12: The piece has been expanded throughout the week to add in and reflect the most recent match results. It originally ran on March 8 to preview everything ahead of the first match.

Listing image by Flickr user LNG0004