O Meien on AlphaGo
Posted: Mon Nov 11, 2019 2:55 am
I made a very small dent in the tsundoku on my bedside cabinet last night, and turned at last to a book by O Meien on "The New Age of Go AI". It was supposed to help me nod off, but it kept me awake. Here's a few of the reasons why.
You may recognise this position as from Game 1 of the million-dollar match between Yi Se-tol and AlphaGo in March 2016. O Meien was present there. He has a special status in the go AI world. Apart from his own interest in computers, he is probably - as a multiple title holder - the highest-ranked player to write about AI in depth.
His book dates from March 2017 and so is really about AI based on training with human games rather than self-play. That doesn't matter too much here, though it does explain why Yi played the odd "shimari" in the lower right. He wanted to achieve a position the computer hadn't seen before. This fuseki arrangement (rather than the one with Black A) had actually appeared a couple of times before, but in effect he probably achieved his objective.
But it was the triangled White 10 that fascinated O. In general, in human play White is reluctant to approach in the top right whenever Black can combine a pincer with another stone (as here). AlphaGo went with it anyway.
Lizzie/LZ (the self-play version) agrees. So there's the first interesting point - the bots trained on human games and self-play agree.
It is also of interest that LZ looks at just three moves: this White 10, B and C, all fairly close. This seems to go against human wisdom, in that White is playing close or contact plays on a side dominated by Black. As I have remarked in other threads, the Japanese pro view appears to be that the bots are aiming for early overconcentration, so the move in such areas has to be a full-frontal attack (shoulder hits are also in the armoury; even the early 3-3 invasion can be seen as inducing overconcentration, and the new outside player's replies as resisting that).
Next interesting point: these three moves are also chosen by LZ if Black makes the bigger (Dosaku) "shimari" at A. But LZ hen gives White a markedly better score! That seems to go against human intuition that A is better than the shimari of the game, which is less "connected" with the upper-right corner stone. Connection can be bad? That's what O seems to be suggesting.
First, O Meien said he approved of White 10 himself. But what he really approved of was White's strategy, which was revealed in the diagram below:
I'll leave you to look up the actual moves (effortful practice!), but the important point is the evaluation of this position. O points out that the Black stone at A is not participating in the fighting, and so he wants to be White. (It is this kind of evaluation that pros often use for counting the game BTW - they keep a debit-credit list of such bad moves in their heads, being able to pin a value on each error.)
O doesn't say specifically, but it seems this also explains why, to a bot, Black's right-side position is better than if it had used the usual shimari at B: it would be even less involved in the fighting and would actually be overconcentrated.
What we seem to come back to time and again is simply that bot play is EFFICIENT. Perhaps there really isn't much more to it than that. Overconcentration is one measure which humans seem able to get to grips with. Maybe another measure is how many of your stones participate in a fight (defined how, thohgh?), and of course if you can efficiently place stones so that they participate in more than one fight, you win the lottery.
You may recognise this position as from Game 1 of the million-dollar match between Yi Se-tol and AlphaGo in March 2016. O Meien was present there. He has a special status in the go AI world. Apart from his own interest in computers, he is probably - as a multiple title holder - the highest-ranked player to write about AI in depth.
His book dates from March 2017 and so is really about AI based on training with human games rather than self-play. That doesn't matter too much here, though it does explain why Yi played the odd "shimari" in the lower right. He wanted to achieve a position the computer hadn't seen before. This fuseki arrangement (rather than the one with Black A) had actually appeared a couple of times before, but in effect he probably achieved his objective.
But it was the triangled White 10 that fascinated O. In general, in human play White is reluctant to approach in the top right whenever Black can combine a pincer with another stone (as here). AlphaGo went with it anyway.
Lizzie/LZ (the self-play version) agrees. So there's the first interesting point - the bots trained on human games and self-play agree.
It is also of interest that LZ looks at just three moves: this White 10, B and C, all fairly close. This seems to go against human wisdom, in that White is playing close or contact plays on a side dominated by Black. As I have remarked in other threads, the Japanese pro view appears to be that the bots are aiming for early overconcentration, so the move in such areas has to be a full-frontal attack (shoulder hits are also in the armoury; even the early 3-3 invasion can be seen as inducing overconcentration, and the new outside player's replies as resisting that).
Next interesting point: these three moves are also chosen by LZ if Black makes the bigger (Dosaku) "shimari" at A. But LZ hen gives White a markedly better score! That seems to go against human intuition that A is better than the shimari of the game, which is less "connected" with the upper-right corner stone. Connection can be bad? That's what O seems to be suggesting.
First, O Meien said he approved of White 10 himself. But what he really approved of was White's strategy, which was revealed in the diagram below:
I'll leave you to look up the actual moves (effortful practice!), but the important point is the evaluation of this position. O points out that the Black stone at A is not participating in the fighting, and so he wants to be White. (It is this kind of evaluation that pros often use for counting the game BTW - they keep a debit-credit list of such bad moves in their heads, being able to pin a value on each error.)
O doesn't say specifically, but it seems this also explains why, to a bot, Black's right-side position is better than if it had used the usual shimari at B: it would be even less involved in the fighting and would actually be overconcentrated.
What we seem to come back to time and again is simply that bot play is EFFICIENT. Perhaps there really isn't much more to it than that. Overconcentration is one measure which humans seem able to get to grips with. Maybe another measure is how many of your stones participate in a fight (defined how, thohgh?), and of course if you can efficiently place stones so that they participate in more than one fight, you win the lottery.
was totally off of Elf's radar (0 repeat 0 playouts). Elf's choice is the beloved underneath attachment at a.
and 
.
, inclusive. 
, is a strong play. Elf stops this variation here after 
because the number of playouts for subsequent plays drops below 1500. I am not qualified to judge this result, except to say that to me it looks playable for Black. Because of the threat to White's center stones, I expect that White will have to give up the 
stone.