# BQM 287

Keywords: EndGame, Question

Moved from L-group/Discussion:

Srki: Ogawa Tomoko says that in diagram below was worth sixteen points. How? Can someone explain?

Ogawa's analysis

Chris Hayashida: Calculating the endgame can be confusing. It's easiest to look at the basic situation with each player getting to move first.

Starting position

## Black moves first

Chris Hayashida: First, let's say Black gets to move first. This is how he will play, ending in gote.

Black gets first move
Black gets first move, cont.

Chris Hayashida: This is the tricky part. White won't play a right away, because it's gote. (Technically, it's reverse sente, but don't worry about that for now.) White will probably play somewhere else on the board instead.

Black gets first move, cont.

Chris Hayashida: Eventually, Black will get around to playing the sequence starting with .

## White moves first

White moves first

Chris Hayashida: Now let's calculate if White gets first move.

White moves first, cont.

Chris Hayashida: In a similar vein, Black won't play a immediately. There are still bigger moves on the board.

White moves first, cont.

Chris Hayashida: Eventually, White will get the sequence starting with .

## Comparing the two positions

Black moves first, final result
• Black 10 points + 2 prisoners
• White 5 points
White moves first, final result
• Black 5 points
• White 13 points + 1 prisoner

Chris Hayashida: As you can see, the first diagram has B+7, and the second has W+9. It's a sixteen point swing.

## Other Questions

What if Black plays here?

Chris Hayashida: The problem with this line of play is that there is ko. I think White is trying to avoid ko. Note that this is *calculation* so this is (in part) why White is trying to read ahead the safer variation.

Srki: Chris, thank you very much, this was very helpful. Everything is clear now.

No ko

This isn't even ko. If white plays captures after , black will play and white cannot defend the double atari because the all the white stones are captured at a. If white plays at instead of , black plays a immediately and the result will be equally devastating.

## Bill's Note

Top side first

Bill: - is sente. If Black allows , Black dies, as per the L-group.

Note that White does not have this sente if Black captures the stones.

Top side first, cont.

Bill: Next, is larger than . After , - is sente.

Top side first, var.1

Bill: If - , Black continues with - , which is sente. The corner is small by comparison.

Because the surroundings are not shown, we do not really know how much a play is worth here. But we do know that the left side and the top side are not independent, and that the play on the left is therefore worth more than 16 points (deiri counting).

Ogawa qualified her remarks, with the sente above in mind: "The time had come to capture at ( in this diagram). In terms of the left edge alone, this move was worth sixteen points. It gave White additional profit on the upper edge by making White a ( in this diagram) sente."

Anyway, in these undefined situations, such calculations are only rough indications.

BQM 287 last edited by ChrisHayashida on October 1, 2009 - 09:46