Fun with sanrensei

Gomoto · Post by **Gomoto** » Mon Oct 21, 2019 11:28 am

From time to time somebody tries to play sanrensei against me. Poor souls, they should know better

In other words, I feel a sudden surge of power if my opponents do so and most of the time ...

But this move beats them all.

This is why I love go. The ultimate bully move. I had a good laugh when it showed up during the analyzing of my last game. I am looking forward to applying it versus my next victims

Click Here To Show Diagram Code: [go]$$B $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . O O O . . . . | $$ | . . . . . . . . . . . X X X X O O . . | $$ | . . . O . . . . . , . . . . . X X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . O X . X W . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X X . . | $$ | . . . . . . . . . . . X X X X O O . . | $$ | . . . . . . . . . . . . O O O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Gomoto · Post by **Gomoto** » Mon Oct 21, 2019 11:30 am

Uberdude · Post by **Uberdude** » Mon Oct 21, 2019 2:51 pm

One of my favourite pro games, Cho vs Takemiya: https://online-go.com/game/425045

xela · Post by **xela** » Mon Oct 21, 2019 3:02 pm

White's winrate: 64,9%

Don't get too excited. KataGo translates this into a score of W+3.8. Nice to have a bit of an edge, but at our amateur level of play it's insignificant compared to the mistakes we're going to make later.

Bill Spight · Post by **Bill Spight** » Mon Oct 21, 2019 3:13 pm

Uberdude wrote:One of my favourite pro games, Cho vs Takemiya: https://online-go.com/game/425045

Interesting.

What's the date? Thanks.

Uberdude · Post by **Uberdude** » Mon Oct 21, 2019 3:26 pm

Bill Spight wrote:
Uberdude wrote:One of my favourite pro games, Cho vs Takemiya: https://online-go.com/game/425045
Interesting. What's the date? Thanks.

Date:
9 October 1996
Event:
21st Japanese Meijin

Gomoto · Post by **Gomoto** » Mon Oct 21, 2019 3:58 pm

KataGo W +3.5 is good enough for me

I have some experience playing against sanrensei as well. And I love it. A move like this has an impact on my opponent that is worth more to me, than if I win the game in the end indeed. I enjoy go for the fun of it as well.

Bill Spight · Post by **Bill Spight** » Mon Oct 21, 2019 5:24 pm

xela wrote:
White's winrate: 64,9%
Don't get too excited. KataGo translates this into a score of W+3.8. Nice to have a bit of an edge, but at our amateur level of play it's insignificant compared to the mistakes we're going to make later.

Don't pooh-pooh small errors in points at the opening stage. A 2 pt. mistake in the opening is consistent with a rank difference of more than 9 stones. Sure, it's not a big deal if otherwise one's opening is perfect, but it isn't.

Uberdude · Post by **Uberdude** » Mon Oct 21, 2019 9:32 pm

To help calibrate your sense of how big opening mistakes are in winrate and points it is instructive to look at mistakes which you already know and stand out to you. For example, I think even a DDK who has read some books on the opening, and most SDKs can tell that this black move is blocking from the wrong side according to our old theory as it doesn't coordinate with the san ren sei stone:

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . X . O . 9 O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

However, KataGo rates this 9 as 42.8% for black and and 2.0 points lead for white, whilst blocking on the 'correct' right side is actually worse at 40.0% and 3 points for white. So perhaps not the best example as it's an instance of old theory being wrong. LZ 247 actually thinks it's a less bad mistake, losing less than 1%, and LZ normally gives bigger winrate changes than KataGo in my small experience so here is an example of their different style. The bots distaste of the old logic of making the san ren sei side stone work with the wall can be understood in the context of them not liking moces on the side, preferring the local efficiency of separating the approach stone from the corner than making some too lose side moyo.

So how about a move bots agree with us, such as this misclick which was meant to be classic joseki at a:

Click Here To Show Diagram Code: [go]$$B $$ +---------------------------------------+ $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 6 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . 8 . . 5 . . a . . . . . . . . . . | $$ | . . . 7 . . . . 9 . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ +---------------------------------------+[/go]

KataGo rates a at 42.6% for black and white leading 2.0 points, a slight mistake vs best move at 3-3 top left at 44.0% and white 1.5 points, so it lost 1.4% and 0.5 points. The misclick move is 36.1% and white 4.5 points, so compared to the joseki move loses 6.4% and 2.5 points.

So if dumb misclicks "only" lose 2.5 points compared to what we thought was correct play, a 3.8 point lead after a few opening moves is similarly good as your opponent being obviously dumb like this. But it's also true that even dan players can make 30+ point mistakes in the middlegame, so avoiding those is more important (my blunder in the recent British championship game was a -57 points according to KataGo, though that was unusually bad).

Bill Spight · Post by **Bill Spight** » Tue Oct 22, 2019 12:39 am

The Elf commentaries tell a somewhat different winrate store than KataGo does.

From GoGoD 1994-01-20i, Liu Jun (W) - Yu Keqiang

Click Here To Show Diagram Code: [go]$$Bcm5 Nirensei vs. Sanrensei, one space pincer $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . 3 . 2 . 5 4 . . | $$ | . . . O . . . . . , . . . . . X a . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . 1 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf thinks that

loses 3½% to par, within the margin of error, I believe. So far, I don't think I have seen Elf give it a loss of more than 5% (probably a minor error) in any context. (Edit: But see below.

) Similarly, it thinks that

loses 4½% to par, maybe an error, maybe not.

Elf prefers

giving it a winrate estimate of 40.9% (54.4k playouts). By comparison it gives a a winrate estimate of 39.3% (4.7k playouts) for a loss of 1½%. IMHO, because of so few playouts, a should inherit its winrate estimate from Elf's choice of White's reply at 9, i.e., 39.7% (34.7k playouts), for a loss of only 1%.

In any event the winrate difference is well within Elf's margin of error. Even though Elf prefers the block at

the difference is not enough to say that the block at a is a mistake. In a casual game the surprise factor of

may give a psychological advantage.

Elf's mainline variation for

is pretty interesting.

Click Here To Show Diagram Code: [go]$$Bcm9 Elf's mainline variation for :b9: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . 5 4 6 . . | $$ | . . . . . . . . . . . X . O . 1 O . . | $$ | . . . O . . . . . , . . . . . X 2 . . | $$ | . . . . . . . . . . . . . . . 3 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . 7 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

(41%, 16.9k playouts) should have some shock value, as well.

Bill Spight · Post by **Bill Spight** » Tue Oct 22, 2019 12:55 am

Uberdude wrote:So if dumb misclicks "only" lose 2.5 points compared to what we thought was correct play, a 3.8 point lead after a few opening moves is similarly good as your opponent being obviously dumb like this.

Well, a misclick is a misclick. However, if Black made a practice of losing 2.5 pts. per move in the opening he'd probably be somewhere in the SDKs. Amateur dans can easily lose 10 - 20 pts. to par in the opening, IMO.

Edit: A loss of only 3.8 pts. in 15 moves per player is actually fairly strong play for an amateur.

And it's actually somewhat less of a loss, since KataGo, along with most other bots, thinks that White starts with an advantage.

Gomoto · Post by **Gomoto** » Tue Oct 22, 2019 5:13 am

I was already quite interested in the 15% difference in evaluation of several middle game positions by KataGo and LZ before this thread. That is quite a margin. I will have to watch some games between Kata and LZ when I have some time and dedication at hand.

Bill Spight · Post by **Bill Spight** » Tue Oct 22, 2019 8:00 am

Sanrensei vs. mukai komoku

Ishida Yoshio (W) - Takemiya Masaki, 1976-07-01a, Honinbo final, game 3

Click Here To Show Diagram Code: [go]$$Bcm5 Sanrensei loses 9% $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . 1 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The winrate estimate for a play depends in part on other available plays. Elf thinks that Black should approach one of the White corners. Not doing so reduces the winrate estimate for

.

Click Here To Show Diagram Code: [go]$$Bcm21 On the same block $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . O . . . . . . . . . . . . . . | $$ | . . X O . . . . . . . . . O O O O . . | $$ | . . X , . O . . . , . . . . X X X . . | $$ | . . . X . . . . . . . . X . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . a . . . . . . . . . 7 . . . . . . | $$ | . . . , . . . . . , . . . . 5 X 3 . . | $$ | . . . O . . . . . . . 1 . O . 4 2 . . | $$ | . . . . . . . . . . . . . 6 . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Later

loses 8% by comarison with a. With the Black moyo on the right side Elf prefers to block at

instead of 24, but only by 2%.

xela · Post by **xela** » Thu Oct 24, 2019 3:53 pm

Bill Spight wrote:Don't pooh-pooh small errors in points at the opening stage. A 2 pt. mistake in the opening is consistent with a rank difference of more than 9 stones. Sure, it's not a big deal if otherwise one's opening is perfect, but it isn't. :)

Interesting stat. Where did you get it from? I'm thinking that a "2 pt mistake" described as such in a human commentary and a "2 pt mistake" comparing the human move with KataGo's suggestion may not be quite the same thing.

Uberdude wrote:One of my favourite pro games, Cho vs Takemiya: https://online-go.com/game/425045

Black makes three "2 pt mistakes" in a row at moves 7-11 according to KataGo. White is also making "mistakes" so the game stays close (black 2-3 points behind, if we believe the AI) for a while. But then Takemiya's play on tengen is another "mistake" (score goes from -3.7 to -5.4; winrate from 40% to 36% based on 10k playouts before and after -- but white's reply was a blunder of equal magnitude).

Oh, and thanks Uberdude, I enjoyed going through that game record :-)

Bill Spight · Post by **Bill Spight** » Thu Oct 24, 2019 5:37 pm

xela wrote:
Bill Spight wrote:Don't pooh-pooh small errors in points at the opening stage. A 2 pt. mistake in the opening is consistent with a rank difference of more than 9 stones. Sure, it's not a big deal if otherwise one's opening is perfect, but it isn't.
Interesting stat. Where did you get it from?

Back in the 1970s statistical analysis of Japanese pro-pro handicap games suggested that, up to 9 stones, each handicap stone was worth a little less than 14 pts. The relationship was surprisingly linear. It was on that basis that I predicted that Japanese komi would increase to 6½ pts. by the year 2000. Almost!

OC, each stone corresponds to a one amateur rank difference.

Now if a player consistently loses 2 pts. per move in the opening, that does not mean that he will average a loss of 2 pts. per move throughout the game. So let's estimate his average loss per move at 1 pt., so he loses around 120 pts. plus per game. And that is approximately equal to the average loss from a 9 rank difference. I misremembered, thinking that the loss from a 9 rank difference was less.

OC, for most players their losses are not unimodal, because they have large average losses in the middle game. OC, they are important, and reducing them is significant. But that actually means that a person who loses 120 points overall actually loses less than an average of 2 pts. per move in the opening.

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