Life In 19x19

One aspect of Go that bots seem to be particularly good at compared to humans is vague centre moves (though LeelaZero wasn't much impressed by Shusaku's famous ear-reddening move). So I thought I'd collect some examples I come across in my bot reviews that stand out to me. Maybe a top pro would also find them, but my feeling is they are pretty wacky even for top humans. I'll hide the answer so you can have a go figuring it out, and once seen can you see some reason why it makes sense?

#1 a variation from Ilya (black) vs Artem in PGETC finals, white to play

Click Here To Show Diagram Code

[go]$$Bc
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O X X X O X . . . . . . . . . . . . |
$$ | O O O O O X X . X . . . . . . . . . . |
$$ | . O X X X O O . . , . . . X . , X . . |
$$ | . . . . O X O . . . . . . . . . . . . |
$$ | . . O X X X . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . O . , . . . |
$$ | . . . . . O . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Yes, I was thinking that moves like this might have been more common by pros in times past, e.g. shin fuseki era. Also I wonder if pros of today do think about them more than they play them, but chicken out of playing them in serious tournaments because they are unsure if they are good so apply caution and go for a more traditional move they can be more confident is pretty good if not the best, whereas these centre moves might be brilliant genius moves or utter rubbish. Perhaps if they drank alcohol instead of tea whilst they played inhibitions would be lowered and we would see more creative play .

Uberdude wrote: Perhaps if they drank alcohol instead of tea whilst they played inhibitions would be lowered and we would see more creative play .

IMO the 21st century so far has been a time of creativity in go, even before the advent of AlphaGo, and modern neural network bots are only adding fuel to the fire.

From Shibano Toramaru 7p vs Huang YiJ 8p (?). White to play.

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . O O O . |
$$ | . . . . . O . . . . . . . O . X O X . |
$$ | . . . O . . . . . , . O . . . X O X . |
$$ | . . . . . . . . . . . . . . . X O X . |
$$ | . . . . . . . . . . . B . X . O X O . |
$$ | . . . . . . . . . . . . . . . . X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . X . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . O X . . , . . . . . , . . . |
$$ | . . . . . O . . X . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

I also got the impression that Elf is not exploratory enough. (And maybe Leela Zero, as well.) Certainly the usual disparity in playouts between its first and second choices gives that impression. If it did not produce such large deltas, I would not have so much confidence in its judgements, because of the small number of playouts. But again, these evaluations are for play, not analysis. To produce good play you don't have to accurately analyze all positions, as long as the ones you analyze less well do not occur very often.

I have also wondered if, at its level of play, depth of exploration is not more important than breadth. For instance, if it is relatively weak on ladders, depth of search may allow it to read a ladder out, and therefore may be more valuable than refining the evaluation of key points.

From a game in the Shuko problem book, black to play. Given this thread it's obviously not answering that odd looking peep just played . LZ 157 and Elf v0 and v1 all quickly zero in on the move Hane Naoki played in the game, though for Elf v1 it's not #1 for long (but is still good).

Click Here To Show Diagram Code

[go]$$Bc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . X X . X . O . . . . . . . . . . . |
$$ | . . O O O . . . . , . . . . . X . . . |
$$ | . . . . . . O . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . O O . O . . . . . . . O . . . . . . |
$$ | . . X . W . O . . . . O . . . O . . . |
$$ | . . . X . X . . . O O X O O . , O . . |
$$ | . . . . . . . X X . X X X X X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Andrew: Some thoughts, but first a small digression.

The position below is not a problem but part of a discussion from a book on how to "surround".



Kimu Sujun says the best move now is for White to play the hanetsugi starting at A. White can live inside Black's area if he starts at B, but Kimu says this is wrong (under the heading "jealousy is bad") and he cites, as the guide to how to surround, the maxim that you must actually make use of your sacrifice stones. The jealous line of course swingeingly damages the White stones in the lower left corner. LZ agrees with his choice.

After that little sequence White turns to the upper right:



Again LZ can apparently accept this move - it displays some alternatives but we are talking a difference of slivers of percentage points.

Kimu presumes Black A next, which is yet again well in the frame for LZ, although it perhaps may end up choosing B or C, again by a smidgeon, but as the book is about surrounding we can't assume Kimu wouldn't have considered and maybe preferred any of these alternative moves in a real game.

Kimu then finishes off his explanation by giving the White move below.



LZ looks at five moves in the this area (as well as A) but once again they are all within a percentage point. So we can say the human pro has done acceptably well so far, and we can presumably follow his advice.

The tricky part comes next. Kimu discusses the White alternative below.



Kimu's reason for rejecting this move was that it is too thin. What I found interesting was that, hitherto, LZ had basically been showing about a single set of traffic lights as it pondered each move, but now it suddenly lit up like a funfair at night, with well over a dozen moves clamouring for attention. That suggests to me some sort of criterion for computer thinking. The human pro generally sees "thinness = bad," the computer sees "thinness = fun!" Both are seeing the same manifestation but interpreting it differently.

The specific problem with the thinness for Kimu is that it invites the good erasing sequence Black A, White B, Black C, and it is good for Black because even after it White still remains thin. And, for the umpteenth time, LZ accepts the human move as one of an elite bunch of moves each almost inseparable from the other, so Kimu is not really open to criticism.

Now we come to the real reason I am posting this example. The erasing move, like the wacky centre moves already discussed and many other similar moves I have seen, involves "sector lines." This concept does not seem to get a mention much nowadays but I am going to suggest it may be a key to understanding AI play. The concept was not discovered by Wilcox (I have a much earlier book by Miyamoto with it in) but Wilcox did discuss it much more and I think we can safely go with his terminology.

However, his understanding of the concept may possibly be questioned. His basic premise was that you play on a sector line to erase. Go any deeper and you get surrounded and cut off. Go any shallower and you are making things easy for the opponent. I wonder whether this is yet another of the traps rationalists fall into - it's logical so it must be true. The real truth is that logic all depends where you start from. In the case of sector lines, the bots seem to start from a different point.

Here, although once more the LZ scores for all the possibilities cluster closely, it marginally prefers D or E, and it seems to me that sector line theory would advise against both.

In the previous examples (and others I have seen) LZ likewise seems to go against our sector line theory and most typically goes one or maybe two steps deeper. What I am arguing for is that (in black box terms) LZ does appear, like us, to follow some sort of sector line theory in that it "sees" sector lines but handles them differently. Sector lines by definition are thin. We worry about that. For a bot that's fun.

Going back to the "surrounding" theme, it's considered a high-level concept. I remember once startling Charles Matthews when I said something about being surprised the concept didn't seem to have filtered through to the west then. Charles's interest was triggered by the fact that Kim Seongjune had told him not long before that it was that concept, new to Charles, that had got him to 6-dan.

Nowadays there is some awareness of the concept here but my impression is that it's still not understood very well. The mindset seems to be that "surrounding" (kakoi, in its strategic technical-term sense) is about making territory tout court. Well, of course, that's involved, but there's a higher level to it. That higher level is "balance". The White keima at Q12 above is praised by Kimu not because it ensures territory but because it ensures balance.

Balance actually has a lot in similar with thinness. The master of balance in go was Takagawa. Bill will remember this well. Mr T was highly successful with that style for a long time, but eventually Sakata, the master of disruption, toppled him. I have a feeling that amateurs tend to think of balance in terms of things settling down, or stability, but the real meaning should be achieving dynamic poise while still on the tightrope.

I believe that was what Kimu was striving for, but even he, as a pro, is not as nimble as LZ on the tightrope. Although we have allowed ourselves to be dazzled by AI which can do fancy tricks on the rope whereas we have so far only been able to achieve a slightly undignified arms-out wobble, I do recall that we felt exactly the same sort of wonder and astonishment when Olga Korbut came along and showed us somersaults and prodigious leaps on the high beam when before we had basically given high scores for just standing up straight with dignity on the beam. And then Nadia Comaneci came along and outdid even Olga with a perfect 10/10!

That seems to me an analogy for what we are seeing today. We humans may think we have achieved some sort of balance in our go. The bots are confounding that. For us to regain poise we need perhaps to make wackiness more mainstream. We have discussed thickness in relation to bots but I don't think we've focused on thinness. It seems thin is fun. Thin is the new black (and white)? Thin is where the somersaults are. The sector lines are our beams.

The examples I've picked so far have been invasion/reduction ones, probably because as a "Geronimo!" leap into the enemy area they are more dramatic and attract attention. But the bots also make nice surrounding moves, for example in that last example instead of white's dodgy peep Shuko suggested a surrounding move near tengen, whilst LZ had a similar idea but a bit more conservative (different judgement on current position / komi? or saw it was too easy to sabaki inside with Shuko's larger move?). With the black move I suppose it's aiming at some thinness of white's g15 knight move so can go a bit closer there, and the pro in the game did indeed attack/defend from j14 direction soon.

About sector lines, I recall reading/hearing somewhere that whilst a used to be a classic sector line breaking reduction idea, some pros had come up with :w1 as being better because they looked at a load of plausible continuations after black's surround at b and they always find a good (but complicated!) way for white to manage the situation. And just now I did a pattern search and it's an older idea than I imagined, Rin Kaiho did it against Takemiya in 1977 and Fujisawa several times in the 90s!

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . b a 1 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Uberdude wrote:The examples I've picked so far have been invasion/reduction ones, probably because as a "Geronimo!" leap into the enemy area they are more dramatic and attract attention. But the bots also make nice surrounding moves, for example in that last example instead of white's dodgy peep Shuko suggested a surrounding move near tengen, whilst LZ had a similar idea but a bit more conservative (different judgement on current position / komi? or saw it was too easy to sabaki inside with Shuko's larger move?). With the black move I suppose it's aiming at some thinness of white's g15 knight move so can go a bit closer there, and the pro in the game did indeed attack/defend from j14 direction soon.

About sector lines, I recall reading/hearing somewhere that whilst a used to be a classic sector line breaking reduction idea, some pros had come up with :w1 as being better because they looked at a load of plausible continuations after black's surround at b and they always find a good (but complicated!) way for white to manage the situation. And just now I did a pattern search and it's an older idea than I imagined, Rin Kaiho did it against Takemiya in 1977 and Fujisawa several times in the 90s!

$$W
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . b a 1 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . b a 1 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Maybe has better followup contact plays than 'a'? It would be interesting to see some concrete sequences. How do you think of it?

John Fairbairn wrote:The position below is not a problem but part of a discussion from a book on how to "surround".

{snip}

Kimu then finishes off his explanation by giving the White move below.



LZ looks at five moves in the this area (as well as A) but once again they are all within a percentage point. So we can say the human pro has done acceptably well so far, and we can presumably follow his advice.

The tricky part comes next. Kimu discusses the White alternative below.

If I understand you correctly from what follows, this jump is also one of the plays that LZ liked.

Kimu's reason for rejecting this move was that it is too thin. What I found interesting was that, hitherto, LZ had basically been showing about a single set of traffic lights as it pondered each move, but now it suddenly lit up like a funfair at night, with well over a dozen moves clamouring for attention.

These moves being Black's replies? IOW, Black had a number of good replies to the jump?

That suggests to me some sort of criterion for computer thinking. The human pro generally sees "thinness = bad," the computer sees "thinness = fun!" Both are seeing the same manifestation but interpreting it differently.

Someone who understand LZ can correct me on this, but I don't think that the number of competing replies matters much, if at all, to its evaluation of a play.

The specific problem with the thinness for Kimu is that it invites the good erasing sequence Black A, White B, Black C, and it is good for Black because even after it White still remains thin. And, for the umpteenth time, LZ accepts the human move as one of an elite bunch of moves each almost inseparable from the other, so Kimu is not really open to criticism.

Does LZ reply to Black A with White B?

BTW, I am attracted to this jump by White, not so much because it looks like a bot move, but because I have been playing over Dosaku's games.

Now we come to the real reason I am posting this example. The erasing move, like the wacky centre moves already discussed and many other similar moves I have seen, involves "sector lines." This concept does not seem to get a mention much nowadays but I am going to suggest it may be a key to understanding AI play. The concept was not discovered by Wilcox (I have a much earlier book by Miyamoto with it in) but Wilcox did discuss it much more and I think we can safely go with his terminology.

I think that Wilcox discovered it independently.

However, his understanding of the concept may possibly be questioned. His basic premise was that you play on a sector line to erase. Go any deeper and you get surrounded and cut off.

No, Wilcox said that if you go any deeper you are invading. Invasions do not necessarily get surrounded and cut off.

Go any shallower and you are making things easy for the opponent.

I think that is Wicox's view, except that playing just above a sector line could be OK. I have seen cases where Go Seigen reduced without playing on or just above a sector line, but higher.

I wonder whether this is yet another of the traps rationalists fall into - it's logical so it must be true.

As I understand it, Wilcox's rules were actually heuristics that he wrote into his go playing program. They are not logical, they are rules that made his program play better.

The real truth is that logic all depends where you start from. In the case of sector lines, the bots seem to start from a different point.

It may well be that LZ and other bots play as though they were cognizant of sector lines, at least as far as reduction goes. In Uberdude's example above, Black's reducing play is one point within a sector line. An invasion, according to Wilcox.

Here, although once more the LZ scores for all the possibilities cluster closely, it marginally prefers D or E, and it seems to me that sector line theory would advise against both.

D is less that one point above the sector line, and would not be disqualified as being too shallow. E would be considered an invasion and perhaps promoted as a peep. Whether Wilcox would vote against it is an open question.

In the previous examples (and others I have seen) LZ likewise seems to go against our sector line theory and most typically goes one or maybe two steps deeper. What I am arguing for is that (in black box terms) LZ does appear, like us, to follow some sort of sector line theory in that it "sees" sector lines but handles them differently. Sector lines by definition are thin. We worry about that. For a bot that's fun.

Today's top bots' view of thickness and thinness is appreciably different from that of humans, but not out of reach, I think. But it will take us a while to refine the concepts.

Balance actually has a lot in similar with thinness. The master of balance in go was Takagawa. Bill will remember this well. Mr T was highly successful with that style for a long time, but eventually Sakata, the master of disruption, toppled him. I have a feeling that amateurs tend to think of balance in terms of things settling down, or stability, but the real meaning should be achieving dynamic poise while still on the tightrope.

I believe that was what Kimu was striving for, but even he, as a pro, is not as nimble as LZ on the tightrope. Although we have allowed ourselves to be dazzled by AI which can do fancy tricks on the rope whereas we have so far only been able to achieve a slightly undignified arms-out wobble, I do recall that we felt exactly the same sort of wonder and astonishment when Olga Korbut came along and showed us somersaults and prodigious leaps on the high beam when before we had basically given high scores for just standing up straight with dignity on the beam. And then Nadia Comaneci came along and outdid even Olga with a perfect 10/10!

That seems to me an analogy for what we are seeing today. We humans may think we have achieved some sort of balance in our go. The bots are confounding that. For us to regain poise we need perhaps to make wackiness more mainstream. We have discussed thickness in relation to bots but I don't think we've focused on thinness. It seems thin is fun. Thin is the new black (and white)? Thin is where the somersaults are. The sector lines are our beams.

Except for saying flexible rather than thin, I pretty much agree. And we have had nimble players, such as Go Seigen and Dosaku.

Uberdude wrote:The examples I've picked so far have been invasion/reduction ones, probably because as a "Geronimo!" leap into the enemy area they are more dramatic and attract attention.

I think it is a good area of research, because I think that the bots have better judgement than we do about such positions, and their choices are not too alien.

About sector lines, I recall reading/hearing somewhere that whilst a used to be a classic sector line breaking reduction idea,

Really? I missed that, unless someone was taking Wilcox too literally.

some pros had come up with :w1 as being better because they looked at a load of plausible continuations after black's surround at b and they always find a good (but complicated!) way for white to manage the situation. And just now I did a pattern search and it's an older idea than I imagined, Rin Kaiho did it against Takemiya in 1977 and Fujisawa several times in the 90s!

$$W
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . b a 1 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . b a 1 . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Didn't Kajiwara make this invasion/reduction/approach?

Click Here To Show Diagram Code

[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 1 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Bill Spight wrote:

That suggests to me some sort of criterion for computer thinking. The human pro generally sees "thinness = bad," the computer sees "thinness = fun!" Both are seeing the same manifestation but interpreting it differently.

Someone who understand LZ can correct me on this, but I don't think that the number of competing replies matters much, if at all, to its evaluation of a play.

I think of the number of plausible replies as being somewhat (inversely) akin to temperature, although clearly it is not quite the same thing. If there are lots of replies with approximately the same win rate, then the position is less "sharp" and there is more room for personal taste, whereas if there's just one good reply then that local situation needs to be attended to right away, and moreover there's apparently only one good way to do so.

Of course, John said "fun" rather than "good", so I'm not sure any of us are actually at odds.

Uberdude wrote:The examples I've picked so far have been invasion/reduction ones, probably because as a "Geronimo!" leap into the enemy area they are more dramatic and attract attention. But the bots also make nice surrounding moves, for example in that last example instead of white's dodgy peep Shuko suggested a surrounding move near tengen, whilst LZ had a similar idea but a bit more conservative (different judgement on current position / komi? or saw it was too easy to sabaki inside with Shuko's larger move?). With the black move I suppose it's aiming at some thinness of white's g15 knight move so can go a bit closer there, and the pro in the game did indeed attack/defend from j14 direction soon.

About sector lines, I recall reading/hearing somewhere that whilst a used to be a classic sector line breaking reduction idea, some pros had come up with :w1 as being better because they looked at a load of plausible continuations after black's surround at b and they always find a good (but complicated!) way for white to manage the situation. And just now I did a pattern search and it's an older idea than I imagined, Rin Kaiho did it against Takemiya in 1977 and Fujisawa several times in the 90s!

$$W
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . b a 1 . . . . . . . . |
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$$ | . . . O . . . . . X . . . . . X . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+

Click Here To Show Diagram Code

[go]$$W
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . O . . . . . X . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . b a 1 . . . . . . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . X . . . . . X . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

The basic theme of the large knight's play between two opponent stones on star points goes back at least to the Shin Fuseki era. Perhaps the first game really within the sector lines was this fun one from the 1947 Oteai. Fujisawa played mane-go up to and then invaded when Kitani played on tengen. Black ignored it to turn first to the left side. White won this game.

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[go]$$Bcm23 Fujisawa Kuranosuke (white) - Kitani Minoru 1947-06-18
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X O . . . . . . . . . . . X . . |
$$ | . . . O . . . . . 2 . . . . X X O . . |
$$ | . . . O . . . . . . . . . . . . X . . |
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$$ | . . . . . 5 . . . . . . . . . . . . . |
$$ | . . . O . 6 . . . 3 . . . . . X . . . |
$$ | . . . . . . . . . . . . 4 . . . . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
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$$ | . . O . . . . . . . . . . . . X . . . |
$$ | . . X O O . . . . 1 . . . . . X . . . |
$$ | . . O . . . . . . . . . . . X O X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

The other Fujisawa, Hideyuki's, use of the invasion as White against Takemiya did not work out so well (1-3 over 4 games). In addition, he earlier beat Sakata twice playing the Black side against Sakata's invasion into similar positions, the first time in game 2 of the 16th Oza final below.

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[go]$$Wcm18 Sakata Eio (white) - Fujisawa Hideyuki 1968-10-24
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . O . . . . |
$$ | . . X , . . . 4 . X . . . . . , O . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . 3 . 1 . 2 . . . . . . . . |
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$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , X . . 5 . X . . . . O , O . . |
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$$ | . . . . . . . . 8 . . . . . . . . . . |
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$$ | . . . . . . . . 7 . . . . . . O . . . |
$$ | . . X , . . . . . O . . . . . , . . . |
$$ | . . . . X . . 6 . . . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Another example from following along the live Ahan-Tongshan cup final between Gu Zihao and Fan Tingyu (yike english commentary at http://portal.yikeweiqi.com/online/goli ... om=8175754).

Click Here To Show Diagram Code

[go]$$Bc White (Gu Zihao) to play vs Fan Tingyu
$$ +---------------------------------------+
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X . X X O . . . . . . . . . . . . . |
$$ | . X X O . O . . . . . . . X . . . . . |
$$ | . O X O . . . . . , . . . . . X . . . |
$$ | . O O O . . . . . . . . . . . . . . . |
$$ | . X . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . X . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . O . X O . . . . . . . . . . X . . |
$$ | . . . O O O . O . . . . . . . . . . . |
$$ | . . . O X X . O X , . . . . . X . . . |
$$ | . . O X . X . O . O . . X . . . . . . |
$$ | . . O X X . X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Elf quickly homes in on what it thinks is the vital point of the board in this middlegame postion. Interestingly FineArt giving commentary on Fox has very similar opinion (one point to the right) which Elf gave a few playouts to, but when played agrees is <0.5% better. In the game white shoulder-hit top right, Elf still says key point for black now. FineArt agrees exactly.