A rare way to put a value on thick plays

[John Fairbairn]

I found Murashima Yoshinori's comment on the triangled move (move 17) below unusual and therefore rather interesting.



The prior moves in that corner began with Black answering a high two-space pincer with the rare one-space counter-pincer. Such tight counter-pincers are played either in relation with something on the left side (hardly applicable here) or, through being a strong forcing move, to gain momentum to settle the group in the corner. Black left the corner after White 12, after playing four moves there, but as he played a nobi into the corner (a non-joseki move instead of the usual hane at the triangled point), we can perhaps assume quick settlement was indeed what he was after.

But his comment on move 17 was: "17 is a thick way of playing. But of course with this move I could also have occupied the big point at A." (And White himself took A on the next move.)

There are two aspects to this comment worth discussing.

1. Thick plays add solidity. The group itself has apparently already been settled - that was his original strategic plan in choosing those corner plays and the fact he then left it for a few moves shows he was no longer concerned about its safety. So the thick move is adding something else. What? Well, the obvious thing is that it now allows this Black group to participate in the wider play.

2. Point 1 is interesting (and use of the term 'thick' will no doubt still surprise some people) but it's reasonably obvious when you think about. What is not obvious is what this move is worth, and this is where we encounter the rara avis - a pro putting a value on the thick move (nb thick move rather than thickness - there is a subtle difference). Murashima is clearly equating this move in value to a fuseki big point (A). I think we amateurs would struggle to put a value on the thick move but we'd feel more or less comfortable with guessing the value of a big move. And from that we now have a benchmark as to how big a slow thick move can be.

Perhaps not having to give komi influenced Black, but he did go on to win by a whopping 14 points. By far the largest territory in the game was Black's on the upper left side, and he also made considerable gains on the left side. He caught the White group in the upper left napping before it had time to become a Go Seigen group! In fact, White (Shinohara Masami) admitted that when Black next played at C10, he made a mistake by playing at N3. He said he should have played C13, which of course would have produced a GSG group.

[jeromie]

I like that move. If white plays in the upper left first, then black will have very little to attack on the board. Another weak group might develop as the fuseki continues, but this ensures decent prospects for current territory and a future target to make further profit. Moves that settle (or unsettle) groups are often undervalued by amateurs, at least at my level.

[Kirby]

It would be interesting to know if the pro would actually be willing to play "A" if he played the game again, or if it's simply that the value of "A" is close enough to the thick move that he cannot articulate the difference in value.

Sometimes moves are intuitively superior in a way that's difficult to express.