Sunday Problem #54

This problem is from the Korean tsumego connection , known in Japan as Tenryūzu. The name might be translated into English as ‘Sky Dragon Diagrams’. Most of the problems in the collection are notoriously difficult, making it good practice material for aspiring professional players.

For this Sunday Problem, I tried to pick a relatively easier problem from the collection.

Black to play.

Sunday Problem #53

This is an original problem based on a shape that appeared in the yosai v. nussbrot league game.

Technically, this should be called an endgame problem.

Black to play.

Failure (1)
If Black simply captures one stone with 1, White forces 2–3 in sente, then lives in the corner with 4–6.
Failure (2)
Sometimes, an attachment such as …

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Sunday Problem #52

Celebrating one year of Sunday Problems!

This problem is from Kōno Rin 9p’s Twitter.

Black to play.

Solution (1)
If White gets to play at 1, no combination of two black moves can kill his group, and so we can quickly figure out that black 1 is the only possible starting move.
If White challenges Black with 2, …

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NGD Online League Turns One; League Price Changes

It has soon been exactly one year since we started the current ngd online league – which itself was based on the Nordic Go Academy program we held in 2011–2015.

At the time of writing, we have done 601 game reviews. 325 of these are by yours truly, with Oscar being the second most prolific teacher at 158 reviews. In …

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Sunday Problem #51

This is technically an original problem by me, inspired by the recent ngd league game between Sandmann and le_4TC. However, the shape quickly develops into something that also exists in classical tsumego collections.

Black to play.


Try to avoid kō.

Black’s block of 1 is obvious, and so the question is what to do after white …

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Sunday Problem #50

This is a variant of the infamous carpenter’s square that comes up from time to time in games.

This is a problem for high dan amateur players, so for everybody else I have added a small spoiler that tells the end status of the problem, without actually showing any moves.

Black to play.


Black can kill unconditionally.

Failure …

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KataGo’s ‘Perfect Selfplay’ (2)

Similarly to this post from a few weeks ago, this is a commentary on KataGo’s self-played game with a high number of playouts, ranging from 100,000 to 1,000,000. This commentary was sponsored by @Marissa on the Leela Zero and Friends Discord channel.

See full post to read kifu annotations!

Sunday Problem #49

This is an original problem by me, based on a shape that occurred in a league game between Soeren and Lebertran. Subscribers of the 2021 April league can view the game here.

Black to play.

The problem
This problem is mainly about how to turn ‘a’ and ‘b’ into two eyes for Black. Normally, both of they …

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