How Common is the "Horse Head" Play?

[Katharsys]

I know this is probably a silly topic, but I noticed this move that AlphaGo played in the match against Lee last night but I didn't really hear any commentary about it. Is it a fairly weak move to play this many moves in? I feel like that move chosen by AG was pretty solid and surprising and may have however turned the game considering that Lee didn't bother with a ko in the top left at all. I was also reading through "Lessons in the Fundamentals of Go" today and this move was mentioned as well. But isn't it more of a move for the opening? Did AG know that it could have potential benefit playing it later in the game (not like it knows the importance/name of the move)? Either way, probably from being new, but I thought it was fascinating.

Just wanted to share my thoughts.

[DrStraw]

Isn't that the sake bottle. The horsehead is one move further I think. Regardless, it was not just that shape as much as the connection with E12.

[illluck]

That move (not the shape itself but the fact that it being a flexible, indirectly response to white's previous move) seems to be pretty impressive.

Edit: An amateur (I think around Tygem 7d or so) compared it to a Shusaku move in the famous ear-reddening game. http://tieba.baidu.com/p/4404176046

[Uberdude]

Myungwan Kim commented a lot on that move. He said if it is the best move, which is a distinct possibility, then humans are in trouble because AlphaGo showed a superb sense of positional judgement in playing this unusual move.

[RobertJasiek]

Commentators praise the move 81 in game 2 too much. It is a leaning attack and so attacking from a distance. Each dan knows this strategic concept. Although it is not the first move to consider (first we look at direct attacks or defenses), it belongs to the moves to be considered. We must not lose our minds just because Alphago implicitly applies strategic concepts.

[oren]

Commentators praise the move 81 in game 2 too much. It is a leaning attack and so attacking from a distance. Each dan knows this strategic concept. Although it is not the first move to consider (first we look at direct attacks or defenses), it belongs to the moves to be considered. We must not lose our minds just because Alphago implicitly applies strategic concepts.

And if commentators praise it, it's usually a move worth focusing on and trying to figure out why it is praised.

[Calvin Clark]

If white peeps at D17 after this (a standard move), it helps with black's response.

[Pio2001]

If white peeps at D17 after this (a standard move), it helps with black's response.

Yes, that's what Motoki Noguchi (amateur 7 dan) told us in his commentary: that it was a defense against White D17.