OGS Team League game reviews

[jlt]

To avoid overloading the thread https://forums.online-go.com/t/ogs-june-team-league I suggest to post game reviews, or any technical chat about games in this thread.

I’ve already posted two short reviews of my games:

• OGS June Team League - #74 by jlt
• OGS June Team League - #82 by jlt

Now I will say a few words about the match against @Notbiased.

At move 20, and many times afterwards (except when another part of the board is urgent), the AI wants Black to cut at A and White to protect the cut:

At move 50, Katago wants Black to cut like this:

However the other way of cutting also works:

(I had read until move 53 of the variation but didn’t think about 54).

In this position,

Black connected with B, but A was better for eyeshape in the corner.

In this position,

White should play A. But since White played C, the AI says that Black should play B. I guess this is important for Black to prevent White from making forcing moves against the corner.

In this position,

White’s last move was a mistake and should have been at B. Black responded with A but should have played at B. Black shouldn’t be afraid that White plays at A next. For instance, here is a variation:

Then White can’t block at A, otherwise the sequence Black B, White C, Black D follows and Black can capture two 2 or 3 stones.

N2 is also an insurance for L3.

Yes, reading is hard. Too often I am afraid to be disconnected, but I really need to analyze whether the subsequent fight is good or not, and judge if I can accept that my opponent cuts.

[jlt]

So I’ve already finished my games, I wanted to finish quickly because I’ll be busy from mid-June until mid-July. I only won 2/5 but had a lot of fun and would like to thank @bugcat for organizing this. Good luck to other team members @martin3141 @jiveo @Gia, I hope you will have good games too.

In my last game against ngothonghy, both players made big mistakes, probably the biggest mistake was not to count, but anyway I’ll just pick a position in which I had a dilemma, and which may occur again.

In this position

Click here to see what White should play

C12.

This move captures C14 and in addition, White is thick in the center. Black will need to defend C10. If Black plays C7 then White is happy to defend the corner with C6. If Black B6 then White C7 and Black crawls on the second line. If Black jumps into the center then White can play C8.

The game variation

Is a bit inferior for White. I am not sure I fully understand why, I thought White was not bad because Black crawled on the second line and White had good influence. Maybe because White is slightly less safe, having only one clear eye, and has fewer points since White only captured one stone and Black got a base with a few points and can access the center.

[bugcat]

Interesting. The game move was my first thought and, after considering a bit longer, I came up with the proper one. SDK minds think alike…

I also contemplated leaving the position and playing R15.

[txwolf]

The local move is c12, that I know. That’s the shape☺️Just don’t know if I would stay local, lol

[txwolf]

White K16, if I play the area, I would play at h17, cause there is a peep followup

[jlt]

The white group is not so strong, so it’s urgent to respond to Black’s last move. According to Katago, H17 is 1 point worse than the game move, which itself is 2 points worse than C12.

If White plays H17, will pull out C14 and doesn’t mind that C17 is under attack. I think the reason is that White is not alive either, and Black is ahead in the center.

After Black 16 in the variation below, if White B then Black A. If White A then Black G15.

[txwolf]

I meant k16 would be in h17 instead if I played in that area

[martin3141]

@bugcat

The opening was interesting.

@bugcat

I’ll use this thread for writing a couple of comments on the opening of your game yesterday.

Move 7

(double star point extention from 4-4) - In this setup, after white invades 3-3 black can’t utilise both extentions ideally. Instead approaching the top-left corner is good - perhaps a high approach is consistent with a moyo strategy.

Move 37

In the game the push with D7 showed your desire for going for the center, but it became difficult to make all black stones work together, as the three black stones in the top-left were somewhat weakened.

Blocking with A is big here. If black gets to play B, there is a nice moyo on the bottom side. However if white prevents this, they will incur a local loss when black pushes in with 1 and plays the hane with 3.

Move 39

According to AI blocking with A is still best, but lets ignore that and go for the center. The move in the game, marked with X, creates an enclosure that is full of cutting points. In my experience such a move is not very suited to build a resilient moyo (there are of course exceptions, but basically black needs to be strong nearby).

Instead how about pushing directly with B, or the keima with C?

Move 43 has a similar problem as move 39 in my opinion. It leaves white a cut to work with. Instead the keima is solid.

As a general note, I liked your cosmic style opening to create a setting that perhaps your opponent is less experienced with. But you spent a lot of time early on, which your opponent deliberately used to their advantage (they even commented on this in the Malkovich). It is possible that Notbiased used your time to think, then played their responses to your moves fast to put you under more time pressure.

[bugcat]

(double star point extention from 4-4) - In this setup, after white invades 3-3 black can’t utilise both extentions ideally. Instead approaching the top-left corner is good - perhaps a high approach is consistent with a moyo strategy.

I thought this would be ok since similar openings have been played professionally. I commented on stream that I wanted to try playing a “Takemiya-style sanrensei”.

If we move the lower left to a 4-4 then (7) occurred in Yu–Oya '87, which Black won. If we put it on a 3-4 then (7) can be found in Kim–Lee '88, which Black understandably lost against the young Lee Changho.

A similar move to (7) was played in Izumi–Takagawa '35, which Black won at no komi in the Oteai against Takagawa Kaku; and in Go–Mukai '34 (Black won at no komi, no great feat for Go Seigen). A more modern occurrence is in O–Hashimoto '91, that Black won by a whopping 11.5 points despite giving 5.5 komi.

[martin3141]

Once again you amaze me with your extensive research. However all these games were played previous to the “AI revolution”. I remember reading about it in a book, the justification for such an opening used to be that “An early 3-3 invasion gives the side with 4-4 too much influence and strength, compensating for the fact that one extention ends up being awkward”. But ever since AI showed us how to play 3-3 invasion properly, this argument is outdated.

That being said, it is not a big mistake at all, and I would call it a playable opening move. But still I felt like commenting on it ^^

For reference, the automated AI review at Move 6 in terms of points