Life and death KGS tsumegos

alejo — Sat, 13 Mar 2010 15:55:13 +0000

Sometimes, while watching a game on KGS, you find a game filled with the traditional tsumegos you’ve repeated once and again in Goproblems.com. Here is one of these samples, where you’ll find some problems for double-digit kyus, some that I didn’t manage to solve in real time and some I wouldn’t have solved with a decent amount of time. This game was played on KGS, between Naomichan and Howzulee, white and black respectively, being both 6 dans according to the KGS rating system. You’ll have the whole game loaded in Eidogo by the end of the post, but I’d like to put some pictures of the game.

As you can see from the image below, right at the beginning of the middle game, they both had a floating group, marked with triangle for black and circle for white; moreover, the latter has two unconnected cutting stones. From this image you can already theorise the nature of this game will be involved with fighting, right?

A few moves later, the next situation showed up:

As a you can see, white is trying to close black and kill him, and thus, the played this hane in J14. Unfortunately for white, he has many weaknesses and cutting points around so this wasn’t the best option. On the other hand, if white hadn’t played this capping move and he had played J13, for example, black would still have tried to struggle for life escaping through the J14 gap. If you already imagine what happened, you may want to skip these lines, but once you’ve reached this point and realised white has to sacrifice one side, which one would you retain? You can choose between the upper one, which gives you quite a a moyo on the upper side of the board since we are talking about pressing on the fifth line. But then black would have a strong group on the centre of the board from K7 to K 14 and would have certain advantage in future fights. If you decide to sacrifice the upper side, you are giving out a lot of points by saving the K13 stones, but you may be able to keep some pressure on the K7 group.

A few moves later, the next situation showed up:

On this image you’ll see what a 6 dan player thinks of this situation: give up the upper side and gain strength to attack the central black group, the shape of white around the J13 stone is quite strong but could be improved using some sort of net-like move, H12 or H11 for a lighter connection. But I can’t say I would taken the same path. You can zoom in the image to take a deeper look.

So now black floating group from the upper side has been settled down, but he has a floating group right in the middle, with another couple of white stones cutting at K5. White, on his turn, has two groups of cuttings stones, one around K13 and the previously mentioned around K5. But there is something I’m missing in my description of the board: the aji of R7.

We’ve already talked about the relevance of aji and how to exploit it, but there is nothing better than watching an aji being used by dan players.

An aji which was removed and played a few moves later on, giving as a result the situation replayed on the right side of these lines. As you can see, white has pushed through R11 and black has defended the S11 stones by pushing white from below, expecting white to hit against an unbreakable wall: R8.
Due to the time settings, black wasn’t able to read what was going to happen within the next moves when he played S9. Can you spot the tesuji that white used? In fact, it’s very easy once you’ve spotted it, but I wonder what would happen if you encounter this situation on your blitz games, with just a few seconds per move and your opponent’s last moves have just been “pushing the borders” – style.

Well, all in all, taking into account the last events, I’d like to take a glance at the whole board, just to figure out how the game is developing. This is what we find:

Well, black settled in the upper and lower sides. White has the right side. White’s move 116 is a declaration of war against the central black group. Black happens to lengthen his agony by struggling through the G8 area, shortly before being cut by white, who is then cut by black elsewhere. Whatever, after a series of mutual I’ll-kill-you-before-you-kill-me moves which I can hardly follow, the board appears to be a complete mess:

Black is being encircled and he lacks of eyespace. The only remaining option, as seen in “Attack is the best form of defense“, is to kill the central white group around J 10. White tries to escape through the upper side of the board with move 150. But there is a tesuji which will make white stones die in vain, can you read it? It’s another sample of the inconvenience of playing empty triangles. So, it seems like the easy way to escape didn’t work out, lets look for the hard one.

This sequence, I must admit, is totally beyond my reading ability right now, I could have spend a dozen minutes looking at it and still wouldn’t get it. But it’s possible: white escaped through the lower side. On the thumbnail by the side, you have the answer to this tsumego, the hardest one of the day.

The cross marked stone was sacrificed as move 156, the starting move of the sequence and was captured with move 161.

Finally, while playing the yose, players tend to follow each others move when it’s sente. But there was a point where white didn’t play the expected move or, at least, the one I expected.

Which is the correct answer for black 257?

Ok, then, here I leave you with the full game, loaded into Eidogo. Enjoy it, and, please, comment on the post!!

[Embedded SGF File]

Attack is the best form of defense

alejo — Tue, 23 Feb 2010 22:02:36 +0000

This post is based on a real game I was watching on KGS. The game was actually a blitz game, so players didn’t have much time to think about deep strategies, nor did the audience. And that is referring to myself, I wasn’t able to follow some of the moves in real time, I needed some extra time in order to understand some moves, but the one that stroke me the most was played in the next position.

As you can see, black is surrounding the white group around K6, a big dragon indeed, whose death would mean the end of the match.

Market by A,B and C is the sequence I thought of to make the white group live. I couldn’t be more wrong. Ideas and moves like the next one make me realise the huge level difference between myself and a 5 dan player.The sequence I marked, though it grants life, ends up in gote for myself and is just passive defense. On the real game, the movement was exactly the opposite: sente and attack. In an attempt to kill the black group placed around R14, white played T15.

Due to this attack, black was, as well, forced to find a path to life, where was his path? Killing the white group around Q18. This time, I wasn’t even able to think of a passive defense that black had already placed his offensive defense.

I’ll leave you the game below so that you can enjoy it too

[Embedded SGF File]