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 Post subject: #215: The Intrepid vs. drishti: Deep in the Endgame Weeds
Post #1 Posted: Sat Apr 27, 2013 2:36 am 
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Deep in the Endgame Weeds

The diagram below is the adjourned position from a 9-stone handicap game between drishti and me which we started playing a week ago (Black, drishti, to move). The hour was getting late, so we got kicked out of the go club before we could finish the game. Since drishti could not come to the club this week, we decided it would be great to play the rest of the game online ... and where better to do this than on lifein19x19.com? ;-)

As can be seen from the position, the game is at the late-endgame stage. Since beginning players, double-digit kyus, etc. don't usually have many opportunities to get deep into the weeds of an endgame, I strongly encourage such players to follow this game and to do so not passively but actively.

Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O . O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]
For beginning players:
1). Who is leading in the game?
2). How large is the lead qualitatively?
3). Can you calculate, or at least estimate, the score?
4). It's Black to move, so how should he play next?
For players of any strength:
5). What's the difference in score between White playing at "a" and between Black playing at "b":
a). without the knowledge of what the rest of the board looks like and
b). with the knowledge of the rest of the board?
Click Here To Show Diagram Code
[go]$$Wc
$$ --------------------
$$ . . . . . b a . . . |
$$ O . . . . O X X X . |
$$ X O O . . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #2 Posted: Sat Apr 27, 2013 7:32 am 
Dies with sente

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To the Intrepid :
1) White
2) IMHO :
w has 2 whole corners + half ul corner;
almost all upper side;
the lr corner advances to the center taking almost 1/4 of the board + 9 prisioners;

b has ur corner + r side;
l side with half ul corner;
2 points on lower side;
2 points on upper center;

3) roughly 25 points ahead
4)
b could try something at the ul corner: A18
or he could start closing it's borders: P19 or P9 or B4
5) w playing a takes only 1 point; b playing b takes at least 2 points from w;
a) and b) I can't see no global effects of this play, unless b manages to take the upper side, which I don't see how.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #3 Posted: Sat Apr 27, 2013 7:42 am 
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@bgrieco
Actually, the situation is the other way around. I (White) am hopelessly lost. I'll write about it in a second in my next post.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #4 Posted: Sat Apr 27, 2013 8:08 am 
Gosei

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A question about prisoners: does :b6: mean that white has captured six black stones, or vice versa?

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #5 Posted: Sat Apr 27, 2013 8:51 am 
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For beginning players:
1). Who is leading in the game?
2). How large is the lead qualitatively?
3). Can you calculate, or at least estimate, the score?
4). It's Black to move, so how should he play next?
For players of any strength:
5). What's the difference in score between White playing at "a" and between Black playing at "b":
a). without the knowledge of what the rest of the board looks like and
b). with the knowledge of the rest of the board?
Click Here To Show Diagram Code
[go]$$Wc
$$ --------------------
$$ . . . . . b a . . . |
$$ O . . . . O X X X . |
$$ X O O . . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]
[/quote]

1. Black, I think
2. Not large, less than 10 points
3. Please no
4. T5 sente, then p19
5. I don't know, but if the rest of the board is tiny, Black actually plays n18

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #6 Posted: Sat Apr 27, 2013 9:25 am 
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Prisoners = :b6:, :w3: means that there were 6 Black stones and 3 White stones taken off the board. In other words, White is leading by 3 points, if prisoners are the only consideration.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #7 Posted: Sat Apr 27, 2013 9:30 am 
Gosei

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The Intrepid wrote:
Prisoners = :b6:, :w3: means that there were 6 Black stones and 3 White stones taken off the board. In other words, White is leading by 3 points, if prisoners are the only consideration.

That's how I interpreted it. That being the case:

Even after looking other posts, I count white leading with around 5 points. I'm very interested in learning why white is hopelessly lost.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #8 Posted: Sat Apr 27, 2013 9:54 am 
Lives in sente

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I started responding but then lost my post T.T

Anyways, my responses weren't too interesting except for:

4. T5 and then N18.
5. About 4 points, but as above I think N18 is better for both a) and b).

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #9 Posted: Sat Apr 27, 2013 4:18 pm 
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Not for players.
I'm drunk, so treat this analysis with caution!

Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 3 . . . . |
$$ | . O . . O . . . . O . . 1 . O X X X . |
$$ | . X O O X O . O O X O O 2 . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O . O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]


B 1 looks powerful. If W 2, B connect up for a big gain. So W may resist:


Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . 7 . 3 4 9 . . . |
$$ | . O . . O . . . . O 8 6 1 . O X X X . |
$$ | . X O O X O . O O X O O 5 2 O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O . O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]


However, B 3 threatens to connect again, and W can't resist without collapsing. Another line for W:

Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . 5 . 7 . . . . . |
$$ | . O . . O . . . . O 6 4 1 2 O X X X . |
$$ | . X O O X O . O O X O O 3 . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O . O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

Again, it's a disaster for W.

Sober edt: It's not a disaster, but B gets quite a lot.


Click Here To Show Diagram Code
[go]$$Bcm7 B reacptures at marked stone
$$ ---------------------------------------
$$ | . . . . . . . . . . . X 4 1 3 . . . . |
$$ | . O . . O . . . . O O O B O O X X X . |
$$ | . X O O X O . O O X O O X 2 O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O . O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]


So W needs to let B connect up, and it's very big. So the line below seems a little duff for B.

Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . 1 . . . . |
$$ | . O . . O . . . . O . . 2 . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O . O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #10 Posted: Sun Apr 28, 2013 5:38 am 
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Warrning! A wall of text incoming! :D

First, please note that the title of the thread contains a play on words, or, more accurately, play on idioms. Whereas "getting into the weeds" means getting into the detail of something (often implying getting into too much detail), the expression "in the weeds" usually refers to someone (especially a waiter at a restaurant) being hopelessly behind. Thus, although the title is meant to convey that the game will contain detailed endgame analysis, the title is also meant to signify that I’ll need to perform a miracle to win this game ... or, more precisely, I’ll need to induce drishti into making a serious mistake if I am to have a chance.

My evaluation of the position is that Black is ahead by 13 points (including prisoners). (There is some trickiness as to whether Black gets to capture the ko in the middle or not, but I think he does; otherwise, the lead would be 12 points.) This is a lot in itself in any endgame, but here the real problem is that almost wherever Black chooses to play (and it’s his move), he can expect to keep sente, while just about all of my potential plays end in gote. If the position where within 5-6 points, I would adopt the strategy of making optimal moves, hoping to capitalize on small mistakes from my opponent--a reasonable strategy given the playing strength disparity and given that drishti has not had much endgame practice or practice counting in the past. However, with 13 points difference and with the given sente/gote-plays distribution, such a strategy is doomed to failure. Thus, I need to resort to making at least one overplay somewhere (a move that leads to a loss of points, objectively speaking, but one that may induce a mistake from the opponent).

As a parenthetical remark, I should say that it’s very enjoyable for me to play lost positions. It’s very liberating in many ways. When the position is balanced or one player has only a small lead, a player needs to be weary of pressing his attack too far, of overextending, of making mistakes big and small. However, when the game is hopeless, such as here, it’s possible to try playing anything, even the most ridiculous invasions and overplays, because whether one loses by 10 points or by 100, it’s still only 1:0. Beginning players: take note from this attitude! Rather than hanging your head and resigning after a huge blunder, look at the position again and ask yourself: “what’s the craziest invasion I can do in the position”? Or, stated differently, “what would Magicwand do”? ;)

Answers to previous questions:
1). Black
2). Black is significantly ahead
3). 13 points in Black’s favor (more on that in another post)
4). I’ll come back to what Black should play in my next post
5). To calculate the score difference between White playing in the upper right corner and between Black playing there, we ought to consider the following diagrams:

Click Here To Show Diagram Code
[go]$$Wc
$$ --------------------
$$ . . . . . 3 1 2 . . |
$$ O . . . . O X X X . |
$$ X O O 5 . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . 4 O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]
Notice that Black gets to play :b4: in sente due to the shortage of liberties, so he gets a point this way. (Black may wait with playing this move so that he can use it as a ko threat, for example, but Black should get to make this move eventually, because it's Black's sente and White's gote). Also notice that White ends in gote.

Thus, we end up with this diagram:
Click Here To Show Diagram Code
[go]$$Wc
$$ --------------------
$$ C C C C C O O X M M |
$$ O C C C C O X X X . |
$$ X O O O C O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X M X O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]
Counting the marked intersections yields: B = 3 points, W = 10 points => Score 1 = W - B = +7. (Incidentally, if the reader finds making such calculations difficult in any way, take it from me that it feels difficult only the first few times. After doing a few of these, it becomes fairly straightforward.)

If Black plays in the area first, this leads to the following sequence:
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ . . . 4 3 1 5 . . . |
$$ O . . 6 2 O X X X . |
$$ X O O . . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]
Now there is no shortage of liberties for White, so Black does not get to make a point in sente as before. Also, note that Black again ends up with sente.

Beinners beware!!!
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ . . . . 2 X . . . . |
$$ O . . . 3 O X X X . |
$$ X O O . . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]

Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ . . . . O C 4 . . . |
$$ O . . . X O X X X . |
$$ X O O . 5 O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]

Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ . . . 7 W 6 W . . . |
$$ O . . . X W X X X . |
$$ X O O . X W X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]
The marked group is lost.

Thus, the final diagram is this:
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ C C C O X X X M M M |
$$ O C C O O O X X X . |
$$ X O O C C O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X T . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]
Therefore, the score is B = 3 + (Triangle), W = 7 => Score 2 = 7 - 3 - (Triangle) = 4 - (Triangle).

The value of (Triangle) is equal to 0, 0.5, or 1 depending on how much we know about the rest of the board. Given the knowledge of only the local position, it is unknown who will play first in the area, so the best we can do is say that each player has 50% to do so. If White is the first one to play, neither player will have any points in the area (i.e., Value(White first) = 0). If Black is the first one to play, he will have 1 point, White none (i.e., Value(Black first) = 1). Therefore, without knowing what the rest of the board looks like, (Triangle) = (50% * 1) + (50% * 0) = 0.5 => Score 2 = 4 - 0.5 = 3.5. (Incidentally, from a mathematical point of view, it is more convenient and less error-prone to assign negative values to points of one of the sides, say B points are negative, White positive. Also, it would perhaps be more accurate to write 3.5 +/- 0.5 instead of just 3.5, but I’m getting technical.)

Hence, we conclude that playing at the upper-right corner equals Score(limited knowledge)= Score 2 - Score 1 = 7 - 3.5 = 3.5

If we do know what the rest of the board looks like, then we might be able to determine whether (Triangle will or will not yield Black an extra point. After all, at the end of the game, there are no half-point values anywhere. In the present situation, I believe that Black will be able to make the point there, leading to the conclusion that the Score(full knowledge) = 3.

To summarize, the answer to question 5). is:
a) 3.5
b) 3 (perhaps I’ll return to this later).

For beginners:
6). Now that you know my evaluation of the position, try again to count the board and to play out the endgame to see if you can match my result. In the very least, make sure that you can get that Black, and not White, is leading by a significant number of points. Being able to do such evaluations accurately is of paramount importance! Knowing who is ahead and by how much dictates the strategy which one ought to adopt at a given point.
7). What’s the difference in score between White playing in the lower-left corner (at "a) and Black playing there (at "b")? For each player, is the play sente or gote?
Click Here To Show Diagram Code
[go]$$Bcm1
$$ | . . . . .
$$ | . . X . .
$$ | . . X . X
$$ | . a X O X
$$ | . b O X X
$$ | . . O X O
$$ | . . O O .
$$ | . . . O .
$$ ------------[/go]

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #11 Posted: Sun Apr 28, 2013 5:55 am 
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drishti sent me a message that the following is the move he wishes to play:
Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O 1 O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]
White has terrible shape in the middle: cutting points everywhere, the dead 9 stones still have aji, and so on. However, is :b1: the move that yields Black the most number of points? Is :b1: the move that maximizes Black's chance of success in this game?
For beginners:
8). What is Black theatening to play as followup to :b1:? In other words, if I play tenuki, how would Black continue?
For players of any strength:
9) What is the point difference between :b1: in the game, and the following alternatives:
Click Here To Show Diagram Code
[go]$$Bcm1 Alternative 1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . . X . |
$$ | . . . . . . X O . O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O 1 O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

Click Here To Show Diagram Code
[go]$$Bcm1 Alternative 2
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X C X . . . |
$$ | . . . X . . X X X O . . O O 3 . . X . |
$$ | . . . . . . X O . O . . . 2 1 X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

10). What should White play in response to :b1: in the game?

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #12 Posted: Sun Apr 28, 2013 8:05 am 
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The Intrepid wrote:
...If Black plays in the area first, this leads to the following sequence:
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ . . . 4 3 1 5 . . . |
$$ O . . 6 2 O X X X . |
$$ X O O . . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]
Now there is no shortage of liberties for White, so Black does not get to make a point in sente as before. Also, note that Black again ends up with sente.


Not exactly. Black has this move here:
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ . . . . . 1 . . . . |
$$ O . . 3 2 O X X X . |
$$ X O O . . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]


Therefore, drwmc and I (implicitly in my estimate of the difference between the two moves) visualizes the below sequence:
Click Here To Show Diagram Code
[go]$$Bc
$$ --------------------
$$ . . . . . 1 . . . . |
$$ O . . 2 . O X X X . |
$$ X O O . . O X O X . |
$$ X O X O O X X O O . |
$$ X X X X O X . . . . |
$$ O X . X O X . O O . |
$$ . X X O O X . . X . |
$$ X . . O X . . X . . |
$$ X X X O X X X O . . |
$$ X O O X X O X . . . |[/go]

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #13 Posted: Sun Apr 28, 2013 2:42 pm 
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Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . 2 X . |
$$ | . . . . . . X O 1 O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]
As explained previously, I cannot simply play moves that are optimal from the objective point of view. I have to make overplays. There are two areas where I could make up 10 point or more. The right side is one of them, seeking to take advantage of the aji of the marked White stones and of the potential shortage of liberties of the marked Black stones.
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X W X . |
$$ | . X X X X O . O X X O X O O X X W W . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . W W . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X W . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . . 2 X . |
$$ | . . . . . . X O X O . . . . . B . W . |
$$ | . . X . . . X . . . . . . . O B B . . |
$$ | . . X . X . X O O O . . . . O O B B . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

The second area is in the middle left, where I have a remote chance to cut off the big Black group in the middle while poking out it's potential second eye.
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O B O O . . O X O X . |
$$ | . X X X X O . O B B O B O O X X O O . |
$$ | . . . . . . O . O B B B B O X . . . . |
$$ | . . . X X X X O O O B . B O X . O O . |
$$ | . . X O O O X . . . B B O O X . . X . |
$$ | . . X O X X O O O B M . O X . . X . . |
$$ | . . X O O . O . O B B B O X X X O . . |
$$ | . . . X O O B O B B O O X X O X . . . |
$$ | . . . X . . B B B O . . O O . . . X . |
$$ | . . . . . . B O B O . . . . . X . O . |
$$ | . . X . . . B . . . . . . . O X X . . |
$$ | . . X . X . B O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

The second option does not seem promising at all, but it is definitely possible to go wrong for Black on the right side.

As far as the questions I posed earlier, I'll return to these later. As a teaser, I'll just briefly answer question 7):
The difference between White playing at "a" and Black playing at "b" is 6.5 points. Details to be posted later.
Click Here To Show Diagram Code
[go]$$Bcm1
$$ | . . . . .
$$ | . . X . .
$$ | . . X . X
$$ | . a X O X
$$ | . b O X X
$$ | . . O X O
$$ | . . O O .
$$ | . . . O .
$$ ------------[/go]

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #14 Posted: Sun Apr 28, 2013 5:18 pm 
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The Intrepid wrote:
As far as the questions I posed earlier, I'll return to these later. As a teaser, I'll just briefly answer question 7):
The difference between White playing at "a" and Black playing at "b" is 6.5 points. Details to be posted later.
Click Here To Show Diagram Code
[go]$$Bcm1
$$ | . . . . .
$$ | . . X . .
$$ | . . X . X
$$ | . a X O X
$$ | . b O X X
$$ | . . O X O
$$ | . . O O .
$$ | . . . O .
$$ ------------[/go]


Just a side comment, if you get a 0.5 yose value difference when it's a symmetrical position, double check your calculations. Also, one idea is to extend down instead of hane to keep sente while removing the possibility of the opponent playing the hane himself.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #15 Posted: Sun Apr 28, 2013 5:40 pm 
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Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . 3 2 X . |
$$ | . . . . . . X O 1 O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]


Trying to make sure that a) my groups don't get split up and b) The Intrepid's groups stay split.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #16 Posted: Sun Apr 28, 2013 5:53 pm 
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The overplay did not yield the desired result. :mrgreen: drishti rises to the level. :clap: Now I wonder: how would he have responded to this move?
Click Here To Show Diagram Code
[go]$$Bcm1 Prisoners: ,
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . 2 . X . |
$$ | . . . . . . X O X O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

Oh well, let's see how optimal his moves will be from now on.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #17 Posted: Sun Apr 28, 2013 6:34 pm 
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Click Here To Show Diagram Code
[go]$$Bcm3 Prisoners: :b6: , :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . . O O . 1 O X . |
$$ | . . . . . . X O X O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O 2 O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]
I need to lay low for a little bit. My hope is that Black becomes careless about the liberties of his group on the right, which could offer me a chance to make something happen there. Specifically, I am aiming to play :w1: (for sake of eyespace) and :w3: if the marked group ends up having only two liberties.
Click Here To Show Diagram Code
[go]$$Wcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O B . 3 X . . |
$$ | . . X O O . O . O X X X O B B B O . . |
$$ | . . . X O O X O X X O O B B O B . . . |
$$ | . . . X . . X X X O . . O O . B O X . |
$$ | . . . . . . X O X O . . . . . B . O . |
$$ | . . X . . . X . . . . . . . O B B . 1 |
$$ | . . X . X . X O O O . . . . O O B B . |
$$ | . . X O X O O X X O O . O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

Incidentally, :b1: in the game was not the best move point-wise. Black should have started with :w4:, but I'll write more about that later.

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #18 Posted: Mon Apr 29, 2013 5:27 am 
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Click Here To Show Diagram Code
[go]$$Bcm3 Prisoners: :b6:, :w3:
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . . O . . . . O . . . . O X X X . |
$$ | . X O O X O . O O X O O . . O X O X . |
$$ | . X X X X O . O X X O X O O X X O O . |
$$ | . . . . . . O . O X X X X O X . . . . |
$$ | . . . X X X X O O O X . X O X . O O . |
$$ | . . X O O O X . . . X X O O X . . X . |
$$ | . . X O X X O O O X . . O X . . X . . |
$$ | . . X O O . O . O X X X O X X X O . . |
$$ | . . . X O O X O X X O O X X O X . . . |
$$ | . . . X . . X X X O . 3 O O . 1 O X . |
$$ | . . . . . . X O X O . . . . . X . O . |
$$ | . . X . . . X . . . . . . . O X X . . |
$$ | . . X . X . X O O O . . . . O O X X . |
$$ | . . X O X O O X X O O 2 O . . X O O . |
$$ | . . O X X O X X . X X X O X X X X O . |
$$ | . . O X O O X X X X . . . X O X O . . |
$$ | . . O O . O X . X O O O O X O X O . . |
$$ | . . . O . O X . X O . . . O O O O . . |
$$ ---------------------------------------[/go]

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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #19 Posted: Mon Apr 29, 2013 8:25 am 
Honinbo

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The endgame is fighting strength.

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Everything with love. Stay safe.


Last edited by Bill Spight on Mon Apr 29, 2013 8:07 pm, edited 1 time in total.

This post by Bill Spight was liked by: mitsun
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 Post subject: Re: #215: The Intrepid vs. drishti: Deep in the Endgame Weed
Post #20 Posted: Mon Apr 29, 2013 8:41 am 
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KGS: illluck
Tygem: Trickprey
OGS: illluck
Black's last move is very strong! I was thinking of K7, but this cleanly captures the two stones.

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