Locally Speaking

Example 1  

This example is a slightly modified version from Hane-connect Exercise 3/Discussion. I added a couple of stones so we can count the territory.

White plays first  

The rest at this point is miai. Let's look at the final position.

White plays first, count  

Black has 11 points of territory. White has 8 points of territory plus 1 captured stone, for 9 points.

Net local score: +2.

Black plays first  

The local count is now +5 2/3. That is also the count of the original position, which is a 3 2/3 point Black sente.

To see why, let's look at the follow-ups from here.

Black follow-up  

at .

Black has 12 points of territory plus 2 captured stones, for 14 points. White has 6 points of territory plus 2 captured stones, for 8 points.

Net local score: +6.

White follow-up (ii)  

at . elsewhere. at .

Black has 12 points of territory plus 2 prisoners, for 14 points. White has 6 points of territory plus 3 prisoners, for 9 points.

Net local score: +5

From the position before the follow-ups, it took Black 1 net play to reach +6, and it took White 2 net plays to reach +5. So that position has a local count of 5 2/3, as advertised. And the value of a play in that position is 1/3 by miai counting.

Now, a value of 1/3 is much less than a value of 3 2/3. In a real game, in the vast majority of cases after playing his sente Black will play elsewhere, leaving the local position until near the end of the game.

However, if the local region is the only place left to play Black will of course continue to get a net local score of +6.

This is pretty clear to most players, but it does show the ambiguity of what is best local play. Is it to stop after in the Black plays first diagram, or to continue?

Example 2

White plays first  

When White plays first the first three moves are obvious. But what now? Should Black connect or play elsewhere?

White's threat  

connects at .

White's threat is to save the stone and capture the stone. This play has a miai value of 3 points, as you may verify.

Normally you would expect that Black should protect at instead of allowing the possibility that White can play , but maybe not.

Black plays first  

Black has the obvious hane-tsugi. If this is correct, then the value of a local play is 3 points, and Black may as well reply to White's hane-tsugi above. (The play is ambiguous.)

Black tesuji  

But Black has this tesuji.

Black's threat  

Black threatens this 3 point sente. So Black's descent at is worth 2 points more than the hane-tsugi.

So the descent is correct for Black and a play in the original position is a 4 point gote, as you may verify.

In this example the ambiguity concerns not only whether to continue play locally or play elsewhere, but also which play to make. From the standpoint of yose evaluation, Black to play should descend, but if play is restricted to the local region, the hane-tsugi is correct.