124. Chew (3k) vs Fuego (Bot)

Chew Terr · **#21**

Loons: Yeah, just wasn't sure I liked that the larger portion of the influence faced a black corner.

emeraldemon · **#22**

Click Here To Show Diagram Code: [go]$$Bcm1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 7 . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , . . . . . , . . . . . X . . . | $$ | . . . . . a . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

@xed_over: yes, it has the ability to print move values & sequences and such. But it doesn't start doing any evaluations until we hit a move it doesn't know. Don't worry though, we're almost out of the book, I think this is the last trigger in this line:

if you play a:

Chew Terr · **#23**

Click Here To Show Diagram Code: [go]$$Bcm1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , X 0 . . . , . . . . . X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Hmmm, this one threw me for a loop. I'd seen everything up to this shoulder hit. I almost played counter to the 'when shoulder-hit, play up or sideways' rule of thumb, by jumping to K3. However, I turned that down when I thought about how black could just play on top and lean on my stones to further expand the left side. So I'll stand up first to limit that a bit, and see how it goes. I'm used to playing Kobayashi, not having it played against me, so his shapes look better to me than mine do. I want to claim K17 as soon as possible, so I'd love to get sente out of this...

emeraldemon · **#24**

First move with actual thinking! I'm excited! (also komi is 6.5, correct?)

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . 1 . . . . . . . . . . . . . . | $$ | . . X , X O . . . , . . . . . X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Unhidden:

I gave Fuego 30 mins for this. It believes its win probability is 0.494, so it actually feels slightly behind at this point, but very slightly.

Here's the full sequence Fuego predicts (only hidden for brevity):

This is a long sequence, and I wouldn't put too much stock in it, esp. after the first few moves. I do think the W2 it predicts is interesting, I doubt Chew (or I) would play this move, but I actually like the idea of it: a very loose multi-purpose move, threatening to make a base on the bottom, and also making the right side more urgent (white 4 is a followup that stresses the right stone). About E5 itself, there isn't much to say, I think it's solid. At the beginning it was favoring this sequence:

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . 5 3 4 . . . . . . . . . . . | $$ | . . . . . 1 2 6 . . . . . . . . . . . | $$ | . . X , X O . . . , . . . . . X . . . | $$ | . . . . . O . . . . . 7 . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

But it decided on the more solid play instead of the double hane.

Mnemonic · **#25**

@ chew

Click Here To Show Diagram Code: [go]$$Bcm1 Why not this? $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X , X . . . . , . . . . . X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . W . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

@ Not chew

hyperpape · **#26**

Mnemonic wrote:

perceval · **#27**

Out of curiosity, fuego proabably has some routines to select the next move at least.
Do you know how far they go and how many "rule based candidate" it is considering ?
meaning, did it just select n candidate and evaluate them directly or does its rule engine also construct a few W answers move before turning to MC evaluation of each ?

Chew Terr · **#28**

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . . . . . . . | $$ | . . X , X O . . . 2 . . . . . X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

It's bad that I feel like I'm already behind, but we'll see how long it lasts. It is urgent to get a base for those two stones, so here it is. I would've loved to approach the bottom right, but I feel like almost any approach would get pincered immediately. Better to not approach at all than to let both sides get split. After this, my stones will be stable enough that I can tenuki, even if black denies me that extension. Or I can take the extension and be developing almost as fast as black.

Mnem: I don't like that move for the same reason I didn't jump three spaces: if black takes F4 or G5, its wall is formidable, and I'm only getting third-line territory. Additionally, with that move, I don't even get assured the corner (because of bB2). Because the left side is biggest in the current equation, I did the move that has the most impact on that region.

Marcus · **#29**

Mnemonic's suggested move is (to my knowledge) a very common move when faced with the Kobayashi Fuseki.

Hidden because it discusses Kobayashi strategy, may have an impact on Chew's thoughts:

Loons · **#30**

@Chew

emeraldemon · **#31**

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 3 . . . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Unhidden:

Here's the first few moves of the sequence:

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . 5 . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , 4 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 6 . . | $$ | . . . . X 3 . . . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The only other move it seriously considered was this:

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . 3 . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X . . . . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

emeraldemon · **#32**

perceval wrote:

Out of curiosity, fuego proabably has some routines to select the next move at least.
Do you know how far they go and how many "rule based candidate" it is considering ?
meaning, did it just select n candidate and evaluate them directly or does its rule engine also construct a few W answers move before turning to MC evaluation of each ?

There are some 1st line moves it removes by policy, but everything else is selected directly by UCT search.

daniel_the_smith · **#33**

Chew Terr · **#34**

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 3 . . . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . 4 . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

ratata · **#35**

daniel_the_smith wrote:

daniel_the_smith · **#36**

ratata wrote:

lightvector · **#37**

Chew Terr wrote:

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X 3 . . . . . . . . . . . . . | $$ | . . X , X O a 5 8 O . . . . . X . . . | $$ | . . . . . O 9 6 7 . . . . 4 . . . . . | $$ | . . . . . . b 0 . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This works okay because 'a' and 'b' are miai.

If it goes like this, black can actually eat some stones here.

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X X . . . . . . . . . . . . . | $$ | . . X , X O 1 X O O . . . . . X . . . | $$ | . 9 8 6 4 O X O X . . . . O . . . . . | $$ | . . . 7 5 3 2 O a . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Also black threatens "a". If black later gets to play here first, is there any way for white to deviate?

emeraldemon · **#38**

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . 5 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X X . . . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

I'm still experimenting some with how I can get data from Fuego about its decisions; bear with me while I try some different things and please ask if there's specific info you'd like me to try to find.

First the sequence:

Click Here To Show Diagram Code: [go]$$Bcm15 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . 2 . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . 6 . . . | $$ | . . . . . . . . . . . . . . 7 . 4 . . | $$ | . . . X . . . . . , . . . . . 5 . . . | $$ | . . . . . . . . . . . . . . . . 1 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X X . 3 . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . O . . . . . | $$ | . . . . . . . . . 8 . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

B15 is an interesting choice, leaving enough space around R6 for white to invade later, but threatening to develop on a large scale. B19 and B21 show that Fuego is happy to play for influence. Fuego thinks black has a 49.8% chance to win this game.

I can look at how many times a particular move was visited in the tree, which is a good indication of how much time it spent thinking about that move. Here are all the moves Fuego visited more than 100k times:

Click Here To Show Diagram Code: [go]$$Bcm11 Black's possibilities $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . b . c . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . e . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . a . . | $$ | . . . . . . . . . . . . . . . . d . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . X X . . . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Number of visits:
a: 3,316,615
b: 249,203
c: 144,403
d: 111,646
e: 108,358

A few people (including Chew Terr) commented about H4, but Fuego only visited that move 23 times, so it basically didn't consider it. The only inside attack it thought much about was J3, with 8066 visits.

We can do something similar to see what responses it thinks Chew might play:

Click Here To Show Diagram Code: [go]$$Bcm11 White's possibilities $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . a . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . b . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . 5 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . d . . | $$ | . . . . X X . . . . . . . . . . . . . | $$ | . . X , X O . c . O . . . . . X . . . | $$ | . . . . . O . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Of these, only ''c'' seems unreasonable (looks over-concentrated for this stage of the game).

One note about the choice of R12 (e in diag 2, b in diag 3): Fuego has a strategy called RAVE, which basically says "if a move is good anywhere in the tree, try playing it higher up in the tree". This is a useful heuristic, because it automatically builds in ideas like "my opponent's good move is my good move" and the 1-2-3 rule (if 3 is good, just play that). In this case, I noticed it spent time looking at this sequence:

Click Here To Show Diagram Code: [go]$$Bcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . , . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 7 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . 5 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 6 . . | $$ | . . . . X X . . . . . . . . . . . . . | $$ | . . X , X O . . . O . . . . . X . . . | $$ | . . . . . O . . . . . . . O . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This is a very natural move in this position, and I wonder if the RAVE policy then encouraged both white & black to try R12 earlier in the tree.

Wildclaw · **#39**

hyperpape wrote:

could you elaborate on this point? I had thought that one of the big advantages of Monte Carlo methods is that they make good use of increased computational power, in a way that older programs didn't.

Not really. Min-max can make just as much use of increased computational power. The big advantage of MC is that it is depth first unlike min-max that is width first. That removes the need for a well functioning evaluation algorithm.

A common misconception is that MC playouts are mostly random. It is no more true than saying that human reading is mostly random because we don't go through each path in the exact same order each time. The important part of reading isn't which path you choose first, but which paths you focus most of your concentration on. And the same holds true for MC.

lightvector · **#40**

As a computer science major focusing in AI (and as someone who's followed the computer-go mailing list and the major papers on computer go for a few years), I'd like to add a few comments.

Prior to the development of MCTS (monte-carlo tree search), programs actually didn't make good use of increased computational power. Indeed, for many old-generation programs, such as Gnugo, almost arbitrarily large increases in computational power add hardly any strength improvement at all! This was because old programs lacked a good way to evaluate positions. It didn't matter how deep they could read or how many of the tactics they could figure out, if they couldn't judge the resulting positions.

The "surprise" came when people found that randomly playing it out was actually a pretty good evaluator in Go. Unlike games such as Chess, where randomly shuffling all the pieces will utterly destroy any meaning in the position, in Go, the stones don't move, so that even as you randomly play more moves, the same shapes tend to stick around, and continue to have their effects, whether good or bad. If your group was thick and connected before, it's probably still thick and connected afterwards. If you had good eyeshape before, you probably will still have good eyeshape with a few more stones. If you controlled an area very strongly before, you'll probably still control it very strongly after some random moves.

Basically, the idea is to judge a position by playing it out, while maintaining the "status quo" as much as possible. To that end, a modern go program's playouts are actually very very far from pure random. If the one side during the playout threatens to break a connection, the other side won't play randomly, but will instead connect. If a one side wedges in a one-point jump, then the other side will atari and then connect. If one side plays atari on a group, the other side will connect, or better yet, capture an adjacent group, if possible. If one side plays in the middle of a straight-four eyespace, the other side will respond by playing the other point, to divide it into 2 eyes.

More or less, the playouts will finish the game according to basic instinct. It's not too much of a stretch to imagine why finishing the game according to basic instinct would be a not-terrible way to estimate the value of a position, especially if you do it a lot of times with some random choices of variations and average out the results. Of course, there will be positions that playouts can't handle alone. That's why it's MCTS (monte-carlo tree search), not just MC. You still do the tactical reading nonrandomly in a min-maxing fashion, it's just that you use the above playout method to evaluate the *results*.

124. Chew (3k) vs Fuego (Bot)

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