From: olounela@klaava.Helsinki.FI (Olli Lounela)
Newsgroups: rec.games.go
Subject: Re: Large and small, a problem in a go game (LONG)
Date: 8 Nov 92 14:34:35 GMT
Organization: University of Helsinki

In article <1992Nov8.085858.2101@klaava.Helsinki.FI> cust_ts@klaava.Helsinki.FI (Tero Sand) writes:
>In article <BxDqJt.2rA@nic.umass.edu> s9874203@titan.ucc.umass.edu (s9874203) writes:
>>
>> This is taken from a game I played on IGS. I played black and it is
>>black to move. There are two places I like to play: a or b. The question
>>is: which one is larger?

I'm mixing up the order of some of the comments in earlier postings to
gain some clarity. 

>>I played b, but I prefer a now -- partially
>>because I don't know how to handle the upper-right corner after white
>>played c. 

Let's see: the top looks like this.

>>    A B C D E F G H J K L M N O P Q R S T 
>>19 |. . . . . . . . . . . . . . . . . . .| 19
>>18 |. . . . . . . . . . . . . . . . . . .| 18
>>17 |. . . # . . . . . . a c . . . . # . .| 17 
>>16 |. . # + O . O . . + . . . # . # . O .| 16
>>15 |. . . # # O . . . . . . . . . . . . .| 15
>>14 |. . . . . . . . . . . . . . O . O . .| 14 
>>13 |. . . # . O . . . . . . . . . . . . .| 13
>>12 |. . . . . . . . . . . . . . . . O . .| 12

The three black stones at the top right are more or less stable and
settled.  However, 'a' and s17 are miai (if white plays 'a', black takes
s17 and vice versa) and thus sente for white.  However, if white takes
'a', he still needs another move (e17) to make any territory at the top
since he's open at the bottom (or top, as the case may be :-).  So while
huge, it is not very urgent. 

'c', however, seems to be a bit of an overextension (by white) to me.

>>Shall black play K17 if white play c?  c is dreadful to me.

No way I'd recommend k17 as an answer.  Much better to defend the top
right at s17 and aim at either a large reduction in sente or invasion. 
k17 makes eyes for sure. 

>>Another reason I like a is that I want to give some pressure
>>on upper left white stones.

Those stones are rather light, and very difficult to attack effectively. 
I'd play a bit more patiently and leave the thought of attacking at the
top for the time being. 

>>But are the two b stones on right side light
>>enough that wouldn't be my burden later?
>
>'b' is certainly big, in the sense that by attacking these two stones,
>White can build a large moyo on the lower side. Furthermore, Black can
>live easily with S17, so 'c' isn't really horrible - EXCEPT that it
>strengthens White's stones in the upper left.

The whole board:

>>    A B C D E F G H J K L M N O P Q R S T 
>>19 |. . . . . . . . . . . . . . . . . . .| 19
>>18 |. . . . . . . . . . . . . . . . . . .| 18
>>17 |. . . # . . . . . . a c . . . . # . .| 17 
>>16 |. . # + O . O . . + . . . # . # . O .| 16
>>15 |. . . # # O . . . . . . . . . . . . .| 15
>>14 |. . . . . . . . . . . . . . O . O . .| 14 
>>13 |. . . # . O . . . . . . . . . . . . .| 13
>>12 |. . . . . . . . . . . . . . . . O . .| 12
>>11 |. . . . . . . . . . . . . . . . . . .| 11 
>>10 |. . . # . . . . . + . . . . . # . . .| 10
>> 9 |. . . . . . . . . . . . . . . . . . .|  9
>> 8 |. . . . . . . . . . . . . . . . . . .|  8 
>> 7 |. . . . . . . . . . . . . . b . # . .|  7 
>> 6 |. . # # . . . . . . . . . . . . . . .|  6 
>> 5 |. . O # . . . . . . . . . . . . . . .|  5
>> 4 |. . O + . . . . . + . . . . O + O . .|  4 
>> 3 |. . . O . O . . . . . . . . . . . . .|  3 
>> 2 |. . . . . . . . . . . . . . . . . . .|  2
>> 1 |. . . . . . . . . . . . . . . . . . .|  1
>>    A B C D E F G H J K L M N O P Q R S T 

The group on the right side is certainly weak enough to be a burden, and
not light enough to be sacrificable easily.  A move (at? around?) n10
would make it very light indeed, light enough not to worry black any
more but does black have time to make such a slow move?

I would certainly be tempted to reduce the bottom at m3, making miai of
j3 (if w @ o3) and p3 (or perhaps q3), but that would almost certainly
provoke a double attack.  However, allowing white to play around m4 (if
b @, say, n10) would seem to make the game hard for black. 

Black can try to settle the right side group by attaching at r5, or
perhaps q12, once attacked, and can still do all kinds of mischief at
the bottom even after m4. However, n10 seems such a beautiful
strategical point that I really think black ought to play there.

What does n10 do, then? First, it makes the right side group light, but
you already know that.  However, it also prepares for an invasion at the
bottom and at the top (if black surrounds it), by offering support from
afar.  And furthermore, it reduces the scales of any and all territories
white can make.

>I can't escape the feeling that the game is already difficult for Black.
>Maybe something was wrong with the sequence played, or maybe Black has
>erred earlier.

More than likely :-)

>-Tero Sand
>  EMail: cust_ts@cc.helsinki.fi     Snail mail: Auroran Sairaala os. 6-1
-- 

	Olli, 3 dan
--
E-mail: olounela@cc.helsinki.fi           ! .sig still under construction.