Safe extensions and the 3x3 invasion

I just read about walls in Bruce Wilcox's Sector fights. There is a lot more in there, but I just have to share a few juicy concepts.

The largest safe extension is equal to the height of your wall. Extend to the 3rd line.

So, here is a completely made up position that illustrates the concept:


If you count from the top edge of the board, the black wall is 6 tall, or you can say it reaches the 6th line. The white wall reaches the 5th line. The safe extension is the same number of spaces away from the wall (on the 3rd line). So white can jump out 5 spaces (a "four space jump") and Black can jump 6. The theory is that the height of the wall helps insure the area can't be invaded. I haven't played one of these big extensions and seen it work, but I am trusting it is true.
It matches up with the proverb, "From a 1 stone base jump two, from 2 stones jump three".


And here is the piece that got the "aha" from me. Why do you see an extension from a single 4-4 stone to the middle of the side? I have seen this and it looked like a lone stone out hoping to claim some territory. Why does this make sense?


Take a look at the picture below - this is the same board after a 3-3 invasion by white. Count up how far away that lone stone is from the wall (consider it to be on the third line from the left). AHA! :)


Lastly, I'll do a little plug for Go Dojo - Bruce talks about a LOT more than just this in his section on walls. Among other things he covers diagonal walls, walls with missing stones, jumping walls and how to destroy the effectiveness of opponents walls. Good stuff!

Skybox - experiments with influence

Influence is important in GO, but it is somewhat hard to quantify. Books talk about trading territory for influence, but it is pretty tough to figure out what a fair trade looks like. I can't tell you exactly how to judge this, but an interesting GO variant called "Skybox" is worth a game or 2.


Skybox Setup: Put a black stone on every spot on the first line as shown above.

Skybox rules: One side (white in my example) tries to make a living group. If white can make 1 group with 2 eyes, white wins. So, obviously, black needs to stop white from getting a 2-eyed group.

So, basically, you are playing a regular game of GO, except that black has a ton of influence around the edge of the board. The page on Sensei's that mentions Skybox states that white should fail. We played 1 game at work, and I sort of consider this less of a "game" and more like an "exercise". It is REALLY tough on white, but I think that hints at the power of influence.

It is also interesting to see how to optimize your play as black. Basically, keep it simple and run to the wall when threatened. Don't try tricky cuts, don't try to capture anything, just drop a stone somewhere that destroys eyeshape and run to the wall!

Watching a game of Skybox did make me rethink my assumptions about "best moves". I really encourage you to play a game, err...try the exercise!

Interesting Quote

Don't attack and don't defend - Sonoda Yuichi 9-dan

Something about this quote seems right, but I really don't quite know how to put it in practice. Worth thinking about when playing though!

I found some games of his vs. Cho Chikun which I will look at to see if this quote seems to apply.

Sealing the border

Here is a pretty common situation that I have repeatedly messed up. You are white, you want to claim some territory on the edge. What should your next move be?


What seems like the best move has a flaw. I tend to want to move right to the edge on H and seal the border. Black could easily respond with his own move to the edge on G. Now I tell my self "Mission complete! Border sealed!" and head off to another part of the board.


Black hits me with this (below). Ugh. No escape - adding a stone still leave the 2 stone group in atari. Dead, dead, dead. After falling for this for recently I started wondering, what is the right way to deal with this?


Not long after that, I was watching a game and saw this. I was confused and started thinking the player who did it must be a fool. It seemed like it gave away territory - I didn't like it. But it stuck in my mind. I was reviewing another game, where the player ended up using the move in the top diagrams, and the kibitzers were making fun of it and recommending the move below. So, finally the light bulb went off and I understood that this move is the right one on the side. It is efficient and has some hidden teeth of it's own.


If you play that, and black plays tenuki (Japanese for 'playing somewhere else') white can follow up with the below and threaten to expand the group out to F and beyond.

Motivation

Well, my KGS rank drifted up to 16k and then 15k while I studied and reviewed games but didn't play. I convinced myself that I was gaining skill right along with my rank. Then I got the dreaded question mark, so I played a rated game and lost convincingly. It put me right back to 17k.

So, I am going to try not to let any rating drift convince me of anything anymore. I need to play to improve. If it is 1000 games to Shodan, I have about 980 to go. I guess I am trying to rededicate myself to being a bit more serious about my progress.

So, back to the goban, the books and all the rest. I was enjoying my unearned 15k rank and looking forward to SDK (single digit kyu). I have been playing only a few games and trying to extract the maximum learning out of each one. Maybe it is time to try the opposite approach and just get some more experience on the board.

Ok, my goal for June is 50 rated KGS games. I have 1 completed. So, about 2 a day and I will make it. Let's see if playing more games feels more instructive than careful evaluation of a few games.