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Comment by malanj | Hacker News Reader

After the first 3 games I thought that AlphaGo was far beyond human level, but it's a harder call to make now. It seems very unlikely that an AI would be very close to exactly matching a human, one would expect it to be much stronger or much weaker.

Perhaps humans are closer to the "Perfect Game" than we think? http://hikago.wikia.com/wiki/Hand_of_God The top players estimate they would need a 4 stone advantage to win a perfect player.

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I think AlphaGo is best described as, "Superhuman, but with bugs."[1] The software is very young. I bet these glitches will become ever rarer over time.

> The top players estimate they would need a 4 stone advantage to win a perfect player.

The branching factor for Go is so huge that I doubt anyone or anything comes close to optimal play. I heavily discount the opinions of most Go players on this topic, as they've been right about very little lately. Before AlphaGo existed, many of them thought it would be decades before a Go AI beat the best humans. Before this tournament, the vast majority of them predicted that Lee Sedol would trounce AlphaGo. And during the live commentary, I saw multiple 9 dan pros estimate that AlphaGo was behind, then gradually realize that it was winning. That's exactly what happens when you encounter a much more formidable player.

1. Coined by Eliezer Yudkowsky: https://www.facebook.com/yudkowsky/posts/10154024894449228

"Superhuman, but with bugs." ...this is the future that is coming :)

This :-)

> Before AlphaGo existed, many of them thought it would be decades before a Go AI beat the best humans

To be fair, before the AlphaGo paper came out, many AI researchers thought the same. I'm not in that field, though I do have more than a passing interest. If you'd asked me in 2006, I'd have said we would have robot cars before we had a computer 9dan Go professional -- and that was before all the recent progress on robot cars. My AI researcher friends mostly would have agreed with that.

I think there's something analogous to the anthropic principle happening here. This match is happening now because Google realized we are in the moment when Go AIs are passing the top players in skill. Two years ago, Lee Sedol would have won easily. Two years from now, AlphaGo will win easily. In either case, the match wouldn't have happened at all, or wouldn't receive the same amount of attention.

That assumes a continuous function of Go AI ability. It's not continuous, as alphaGo proves. AlphaGo was a huge leap in ability from the best previous AIs. It was a totally new method, and one given Google scale resources at that.

Right, but alphago was the closest thing we have to the transition - yesterday ais were too weak, today they need to try them against world champs to validate their work

AlphaGo isn't a fixed strength, though. It's substantially stronger now than it was in October. Obviously it's not a completely continuous function, but I think it's close enough to cause this effect.

It is typical for ML systems to surpass human performance while having very different characteristics in what it got right/wrong. For example in ImageNet, DCNN got a lot of points from distinguishing different breeds of dogs with subtle visual differences which are hard for human without training. I think AlphaGo is also demonstrating some of these non-human characteristics as a consequence of the Monte Carlo Tree Search and optimization objective such as the brilliant move as well as the obvious slack moves/mistakes mentioned by the commentators. I suspect that we are not close to the perfect game, as proving a perfect play requires expanding the enormous search tree and we do not have any analytical solutions nor brute force solutions.

Exactly what I thought after the third game.

I now think that a professional like Lee Sedol would have a better chance at beating AlphaGo if he has three hours instead of two.

AlphaGo's advantage seems to be the ability to read more variations more deeply in a shorter amount of time.

Go AI has been developed for some time, and the match happens now because it has reached the level where it can beat top human players. If AlphaGo is far above human level, it just means it's creators waited until they were very certain of a win.

AlphaGo was well below Sedol's level when it played the European champion in October. It must have been a bit uncertain how quickly they could improve it.

> AlphaGo was well below Sedol's level when it played the European champion in October.

How clear is this? If this just comes from professional humans saying "I would have played differently, and I could have beaten Fan Hui by more points" - well, we've seen that humans aren't necessarily very good at judging AG's moves, and we know AG doesn't care how much it wins by.

Fan Hui played more than just the official 5 games against AlphaGo, and did win some of the others.

http://www.nature.com/nature/journal/v529/n7587/fig_tab/natu...

It is not far beyond the human level. Lee Sedol already admitted that he had some psychological strategies that he employs that AlphaGo is completely impervious to.

With AlphaGo, it doesn't understand the moves like a human would. It simply looks at what other humans have played and considers that within its search tree.

>Lee Sedol already admitted that he had some psychological strategies that he employs that AlphaGo is completely impervious to

I wonder if another way to word this is

"Human are overfitted to dealing with other humans and are somewhat unprepared with dealing with alien intelligences such as AI's."

It is incorrect to consider this form of AI as an "intelligence", and it's definitely not "alien". The hype train is a bit ridiculous, and even DeepMind and Google isn't go as far as to state that "humans are overfitted". That is hilarious.

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