BQM 387

Black to play  

It says, "Assume that there is nothing else worth considering on the board and try to figure out the best sequence in which to play them... and try to assign a numerical value ... to each move."

I correctly read c as two points sente.

I thought b was one point double sente. If black takes b, white must connect by filling own territory (because we're assuming there's nothing else on the board big enough to be worth considering). But if white takes b, black must connect or else white takes the point above in sente for one point.

Incorrect answer to A, dia. 1  

And I thought a was surely 1 point sente. If , or else black gets the marked point of territory.

Incorrect answer to A, dia. 2, connects at  

However, if white moves first, , , and force white responses, though white gains one point for capture in gote.

But Tomoko says a is 1.5 points sente.

b, White first  

The play at x removes or defends one point at y. So x is a one point gote play, and Black has half a point (we may think of it like "equity") at y. "Nothing else worth considering" does not exclude the larger plays on the first line; that may be your difficulty ;)

b, Black first  

Black has a full point at y, and White can no longer hane at z, and the value of Black x increased. Big, but a White answer (at x?) is hardly forced (we think of x as "Black's sente" now), so not sente. After Black x, eventually White will lose the a points of territory.

That makes 3 + 0.5 points difference between the two situations, in gote either way.

Personally I think miai counting is easier to understand though :/

3 point gote  

Dieter: in deiri counting, b is a 3 point gote move.

3 point gote - Black  

If , White doesn't usually answer. Next, Black gets in sente. Follow-up moves which are sente are simply added to the sequence to evaluate the score. Black makes the circled point.

3 point gote - White  

Here too, is a sente follow-up. On the first line we average out the 2-point gote endgame play, assuming the territory border at x. White makes two circled points, compared to the previous diagram.

Combined, it's a 3 points double gote.

In miai counting we see a 3 point difference, with a local tally of 2, giving it a value of 3/2=1.5

Canonical play  

Even though White answered with , is gote. It is just that there was no place else to play after . (In a way, you can call sente, since White answered it, but that was accidental.)

Black to play  

After , in the local region there are no points, but if Black plays in this diagram, Black gets 1 point at . That means that after Black's equity in the local region is 1/2 point. gains 1/2 point, making the local score 0, and in this diagram also gains 1/2 point, making the local score 1 (for Black).

White to play  

If we back up to just before and suppose that White plays first in the local region, White can capture the stone for a local score of -1 (one point for White). Before that play we consider the local region to be worth -1/4 point. White's play gains 3/4 point, for a local score of -1, and Black's play also gains 3/4 point, for a local score of +1/2.

gains 3/4 point, but only gains 1/2 point. That's why is gote. If there were a play that would gain more than 1/2 point for White, White would play it instead of .

Similarly, in the canonical play diagram gains 1.5 points, while only gains 1 point, so is gote, too.