Lee Se-dol will be able to exploit artificial intelligence (AI) AlphaGo's weaknesses with creative and unexpected moves in the final of the five-game match, today, according to analysts.
After scoring his first win following three straight losses in the Google DeepMind Challenge Match, Lee will be seeking revenge against AlphaGo in the historic final human versus machine game.
Professional go players and AI experts expect Lee will play more with his original aggressive, creative style.
“Lee has already learned that AlphaGo tends to make strange moves when it faces unfavorable conditions,” said professional eighth-dan go player Kwon Gap-yong, who also has been a mentor to Lee. “Lee will have more of a chance of winning the final match if he makes key moves that are difficult to read.”
Other go experts warned that the machine may not make a mistake in the final round.
“The chance of Lee winning is still below 50 percent considering AlphaGo's superb calculations though Lee found a strategy to beat the AI program in the fourth game,” Korean ninth-dan professional go player Hong Min-pyo said.
Korea Baduk Association Vice President Park Chi-mun said, “Lee's task here will be to engage in a tussle without taking too many risks.”
On Sunday, Lee clinched a long-awaited first win against the AI in the fourth game.
Lee forced a resignation from the program in 180 moves.
He made a key move in the 78th round of the game and led AlphaGo to commit to a “strange” position on the right edge of the board. Despite the program recovering its normal play mode and trying to make up the points it had lost, Lee succeeded in defending his advantage with safer moves.
Once the AI concluded that the probability of its loss was too high to overcome, it popped up a message that read, “AlphaGo resigns. The result ‘W+resign' was added to the game information.” AlphaGo programmer Aja Huang, who placed the stones on the board on behalf of the machine throughout the competition, made the actual move of “throwing the stone” to resign.
After the game, Lee said he has discovered that the machine has two weaknesses.
“AlphaGo seems to have more difficulty playing with black than white,” he said. “It also revealed some kind of bug when it faced unexpected positions.”
DeepMind CEO Demis Hassabis said, “AlphaGo seems to have realized its mistake in the 87th move,” admitting that its winning rate, which was about 70 percent in the 79th move, dropped below 50 percent in the 87th move.
He said it is difficult to tell AlphaGo's strategic move from a mistake because it is designed to make decisions that will lead to the highest win rate. Such an algorithm structure proved successful in the first three games when the machine maintained advantages throughout most of the match, but not when facing an unfavorable condition.
“We have designed AlphaGo to learn by itself by repeating self-plays,” said David Silver, Google DeepMind's AlphaGo team leader. “But such an algorithm must have hulls in it that we cannot know about. Lee was able to push AlphaGo to expose such a weakness.”
A Korea Baduk Association spokesman said, “AlphaGo, which had played like a top-class professional go player up to that point, abruptly changed into an entry-level player. Even when it could take a step back and head to a close match, it repeated preposterous moves.”
Google and the association, which jointly organized the showdown, had previously agreed that the match will go through the fifth game even after the victory was settled with the first three wins by AlphaGo.
In the final match, Lee will play first with black stones, without flipping a coin or drawing straws, as the DeepMind CEO accepted his request to do so. Consequently, Lee will yield 7.5 compensation points to AlphaGo.
The game is scheduled to start at 1 p.m. today at the Four Seasons Hotel in central Seoul.
Korean Language
이세돌 "바둑만큼 정확한게 없어. 남 탓할 수 없어"
MBC다큐스페셜 '세기의 대결 이세돌 vs. 알파고' 14일 방송
'바둑만큼 정확한 게 없어요. 남 탓할 수 없잖아요. 자기가 오롯이 책임진다는 것을 인정하고….'(이세돌)
MBC TV 'MBC스페셜'은 14일 밤 11시10분 '세기의 대결 이세돌 vs. 알파고'를 방송한다.
프로그램은 전세계의 눈이 집중된 가운데 서울에서 진행되는 이세돌 9단과 인공지능 바둑 프로그램 알파고의 세기의 대국이 가진 의미와 이를 둘러싼 반응·전망 등을 조명하고, 이세돌과의 인터뷰도 전한다.
바둑이 가진 경우의 수는 최대 250의 150승으로 천문학적 수에 달하기에 인간은 많은 부분을 직관에 의존해 경우의 수를 좁혀나간다. 구글이 알파고의 상대로 이세돌을 선택한 이유가 이세돌이 가장 창의적인 바둑을 두기 때문이었음은 인간이 가진 직관의 힘을 시사한다.
프로그램은 기계가 어떤 방법으로 사람의 수 읽기 능력과 형세를 이해하는 능력을 흉내 낼 수 있는지 살피고, 이세돌과 알파고의 대국을 통해 구글이 추구하는 바는 무엇인지 알아본다고 밝혔다.
제작진은 대국 전 이세돌이 가수 김장훈과 가진 인터뷰를 전했다. 김장훈은 바둑 아마 5단이자, 이세돌과 친분이 깊다.
이세돌은 알파고와의 대국에 대해 '일단 설레잖아요. 아무래도…. 정말 설레지 않으면 사실 사람이 어떻게 살아갑니까. 그런 흥분이 없으면…. 근데 진짜 바둑으로 오랜만에 이렇게 좀 설레는 마음이 생긴 것 같아요'라며 매너리즘에 빠진 자신에게 큰 자극이 됐다고 말했다.
이세돌은 이와 함께 5세에 처음 바둑을 배운 일부터 아버지로부터 죽도록 혼났던 기억들, 힘겨운 서울 살이에 방황했던 이야기 등을 풀어놓았다.
그는 '조훈현 국수님이 89년도에 (응씨배 세계기전) 우승하잖아요. 카퍼레이드가 너무 멋있는 거예요. 그거 보고서 일곱 살 때부터 프로기사가 되겠단 생각으로 공부한 거예요'라고 말했다.
13세에 입단해 천재 소리를 들었지만 3~4년 동안 별다른 성과 없이 보내던 그는 아버지의 죽음을 계기로 독기를 품게 됐다고 밝혔다.
이세돌은 '독기가 없었어요. 어느 정도는 인정은 받고 있었고 어린 나이에 큰돈은 아니지만 그 당시 돈을 벌고 있는 거고. 친구들이 중학생인데 떡볶이라도 먹을 땐 제가 돈 내지 않습니까. 그런 거에 만족하고 있었던 거죠'라며 '근데 아버지가 건강이 안 좋아지시고 돌아가시니까 아차 싶더라고요. 아, 이게 아니구나. 사실 우승한 거 보여줬으면 얼마나 좋았겠어요. 그래서 그때 이제 맘 잡고 열심히 한 거죠'라고 말했다. (연합뉴스)