ChiyoDad began learning Go (aka 围棋, 바둑, 囲碁) from books and the internet on June 1st of 2005. On his blog ChiyoDad documented his study journal, product/book reviews and links to other sites that had been helpfully to beginners. (Rec.: The blog is outdated as it only shows postings from June 2005 till February 2008. Actually there do not exist any game records on KGS and latest entry in Sensei’s Library is dated on 7th April 2010 he played at level 8kyu.)
date (1st publishing): Monday, January 29, 2007
(original) title: Furikawari and the “Why” behind it
author: ChiyoDad (San Francisco Bay Area, California, United States)
Trading Places: Furikawari
In a recent game, one of White’s moves in a corner battle (number 8 in the image above) made me (Black) consider taking an opportunity for furikawari; that is, an exchange of potential territory.
In the opening of this game, White seemed to be mimicking my High Chinese Opening. This fuseki shares some of the potential of the sanrensei (stones on the star-points of one side) in developing a center-facing territorial framework. The challenge for the opponent would then become the task of invading or reducing the framework.
With my stone at D10 and the approach at D6, I had generally expected White to give me the left side so that she could build a right-facing wall and a moyo that I would have to later reduce.
However, the atari of move 8 seemed to suggest that White wanted to take the side, so I obliged with the sequence shown above to take the corner, and eventually, the bottom.
White got an upward-facing wall on the left; but it’s potential was somewhat blunted by my stone at D10.
In the course of this game, the exchange favored Black.
Applying a sanrensei guideline
I can’t say that the territorial exchange that took place in that game was fundamentally advantageous or disadvantageous. After all, White could still push my D10 stone against her wall with a pincer in either C12 or D12 (see picture A).
My decision to play for the exchange was influenced by a guideline for using the sanrensei fuseki that Shukaku Takagawa provided in the first chapter of The Power of The Star-Point. (Rec. by MySRSBlog: The original blog link is broken and no more existing.)
The diagram above shows a possible outcome after White’s approach and Black’s pincer. If White jumps into the corner, then Black makes good use of his sanrensei by blocking in the direction of the center stone (Q10).
The result yields a large zone of influence from the stone on O16 to Q10. Ideally (but very unlikely), Black may be able to turn this zone into solid territory. The more likely outcome is that White will be forced to invade or reduce that zone; and Black’s massive wall will give him the upper hand.
Blocking toward the left makes less effective use of the sanrensei. Although Black takes the top, White undermines the potential of using the sanrensei to build a large framework on the right.
In my game, given that a successful furikawari could have allowed me to deny White a similar framework from her opposing Chinese Opening, it seemed to make sense to play for the exchange.