Wrong tesuji ?
JR
Reading Tesuji by James Davies (3rd printing 1984), problem 3 p. 81 with the
answer (p. 82) seems wrong to me: white win the capture race, but to get a
dead shape ...
Is my view correct ?
Regards,
Jr
Mike Mallory
"JR" <j...@nospam.com> wrote in message news:BB331845.9518%j...@nospam.com...
Mark Space
looks alive to me:
. . . . . . . |
. . . . . . . |
. . . . . # # |
. . . . . # O b
. . . . , # O |
. . # # # O O c
. . a O O # # #
--------O-O-O-+
Black to play, but a and b are miai, yes? Then white c, or if black c
white captures a living shape. Or did I err?
Nick Wedd
<mark_s...@hotmail.com> writes
Looks dead to me.
. . . . . . . |
. . . . . . . |
. . . . . # # |
. . . . . # O |
. . . . , # O |
. . # # # O O |
. . . O O # # #
--------O-O-O-+
If Black a White b, we have
. . . . . . . |
. . . . . . . |
. . . . . # # |
. . . . . # O O
. . . . , # O |
. . # # # O O |
. . # O O # # #
--------O-O-O-+
then Black plays at T3, killing everything. Yes, if White could capture
the four stones he would have a living shape, but to capture it he has
to start by putting it in atari, and he can't do that.
If Black b White a, we have
. . . . . . . |
. . . . . . . |
. . . . . # # |
. . . . . # O #
. . . . , # O |
. . # # # O O |
. . O O O # # #
--------O-O-O-+
then Black N2, White T1, Black O1, killing everything:
. . . . . . . |
. . . . . . . |
. . . . . # # |
. . . . . # O #
. . . . , # O |
. . # # # O O |
. # O O O # # #
----#---O-O-O-O
Nick
--
Nick Wedd ni...@maproom.co.uk
-
>> JR wrote:
>>> Reading Tesuji by James Davies (3rd printing 1984), problem 3 p. 81
>>> with the answer (p. 82) seems wrong to me: white win the capture
>>> race, but to get a dead shape ... Is my view correct ?
> Mark Space <mark_s...@hotmail.com> writes
>> looks alive to me:
>>
>> . . . . . . . |
>> . . . . . . . |
>> . . . . . # # |
>> . . . . . # O b
>> . . . . , # O |
>> . . # # # O O c
>> . . a O O # # #
>> --------O-O-O-+
>>
>> Black to play, but a and b are miai, yes? Then white c,
>> or if black c white captures a living shape. Or did I err?
From: Nick Wedd <ni...@maproom.co.uk> ( Official BGA Representative )
> Looks dead to me.
>
> . . . . . . . |
> . . . . . . . |
> . . . . . # # |
> . . . . . # O |
> . . . . , # O |
> . . # # # O O |
> . . . O O # # #
> --------O-O-O-+
>
> If Black a White b, we have
>
> . . . . . . . |
> . . . . . . . |
> . . . . . # # |
> . . . . . # O O
> . . . . , # O |
> . . # # # O O |
> . . # O O # # #
> --------O-O-O-+
>
> then Black plays at T3, killing everything. Yes, if White could
> capture the four stones he would have a living shape, but to capture
> it he has to start by putting it in atari, and he can't do that.
As usual, Nick Wedd of the BGA, gets it *-wrong-* again.
There are only three stones (not four) for White ("O") to capture,
but in any case White lives by the sequence:
. . . . . . . |
. . . . . . . | White at "a" and then at "c".
. . . . . # # | Black ("#") plays `b' at 1 or 2.
. . . . . # O 1
. . . . , # O |
. . # # # O O a
. . 2 O O # # #
--------O-O-O-c
Then White ("O") lives by _miai_ with two eyes-shape inside the
three-stone capture or by making another eye shape at 2 or 1.
- regards
- jb
MHenry
The problem Jr wrote about actually looks like this, I think.
. . . . . . . |
. . . . # . . |
. . . . # O . |
. . . . # O . |
. . . , # O . |
. # # # O O . |
. . O O # # . |
. . . . . . . |
The answer leaves this position
. . . . . . . . |
. . . . . # # . |
. . . . . # O . |
. . . . . # O . |
. . . . , # O . |
. . # # # O O . |
. . . O O # # # |
. . . . O O O . |
Played in this sequence
. . . . . . . |
. . . . # D . |
. . . . # O . |
. . . , # O . |
. # # # O O . |
. . O O # # B |
. . . A C E . |
The book says...
if white played A at B, and Black played above B, then E [White's
intervening move forced or assumed, I guess] would put him in a fix.
MHenry
Mark Space
- wrote:
>>Mark Space <mark_s...@hotmail.com> writes
>>
>>>looks alive to me:
>>>
>>>. . . . . . . |
>>>. . . . . . . |
>>>. . . . . # # |
>>>. . . . . # O b
>>>. . . . , # O |
>>>. . # # # O O c
>>>. . a O O # # #
>>>--------O-O-O-+
>>>
>>>Black to play,
BLACK to play, not white. Sure if white gets to make two moves in a row
he can live easily, but that's not the case here. The position arises
from the following problem: White to play and live.
. . . . . . . |
. . . . . . . |
. . . . . # . |
. . . . . # O |
. . . . , # O |
. . # # # O O |
. . O O # # |
--------------+
The answer given is:
. . . . . . . |
. . . . . . . |
. . . . . # 4 |
. . . . . # O |
. . . . , # O |
. . # # # O O |
. . O O # # 2
--------1-3-5-+
So you can see it's plainly blacks turn at this point.
> From: Nick Wedd <ni...@maproom.co.uk> ( Official BGA Representative )
>
>>Looks dead to me.
>>If Black a White b, we have
>>
>>. . . . . . . |
>>. . . . . . . |
>>. . . . . # # |
>>. . . . . # O O
>>. . . . , # O |
>>. . # # # O O |
>>. . # O O # # #
>>--------O-O-O-+
>>
>>then Black plays at T3, killing everything. Yes, if White could
>>capture the four stones he would have a living shape,
I think he was refering to "four stones" after B played T3, i.e. this
position:
. . . . . . . |
. . . . . . . |
. . . . . # # |
. . . . . # O O
. . . . , # O |
. . # # # O O #
. . # O O # # #
--------O-O-O-+
But he's right, white cannot put the four black stones in atari.
-
> JR <j...@nospam.com> wrote:
>> Reading Tesuji by James Davies (3rd printing 1984), problem 3 p. 81
>> with the answer (p. 82) seems wrong to me: white win the capture
>> race, but to get a dead shape ... Is my view correct ?
From: MHenry <MHe...@NoSpam.net>
> The problem Jr wrote about actually looks like this, I think.
>
> . . . . . . . |
> . . . . # . . |
> . . . . # O . | "Problem 3" diagram, p.81
> . . . . # O . | ( in First Printing, April 1975 )
> . . . , # O . |
> . # # # O O . |
> . . O O # # . |
> . . . . . . . |
>
>
> The answer leaves this position
>
> . . . . . . . . |
> . . . . . # # . |
> . . . . . # O . |
> . . . . . # O . |
> . . . . , # O . |
> . . # # # O O . |
> . . . O O # # # |
> . . . . O O O . |
Maybe so, but in the April 1975 First Printing I have:
. . . . . . . . |
. . . . . # # . |
. . . . . # O . | p.82 "Ans. to Prob. 3" ???
. . . . , # O . |
. . # # # O O . | ( with -Black- to move ... )
. . . O O # # # |
. . . . O O O . |
one line erroneously omitted, changing the problem statement of course.
> Played in this sequence
>
> . . . . . . . |
> . . . . # D . |
> . . . . # O . |
> . . . , # O . |
> . # # # O O . |
> . . O O # # B |
> . . . A C E . |
>
> The book says...
>
> if white played A at B, and Black played above B, then E [White's
> intervening move forced or assumed, I guess] would put him in a fix.
MHenry's last diagram would then look like this: ( incorrect )
. . . . . . . |
. . . . # # . |
. . . . # O . |
. . . , # O . |
. # # # O O . |
. . O O # # # |
. . . O O O . |
which corresponds to the error in the April 1975 First Printing
(p.82) yet not the description of the original problem statement
on p.81, with that one -extra- line of a Black-White stone pair.
Perhaps James Davies sought to illustrate some bizarre example of
"empty-triangle sente" in corner-play (sic!) but given either
problem statement, a more obvious continuation could have been:
. . . . . . . |
. . . . # . . |
. . . . # O . |
. . . . # O . |
. . . , # O . | White plays simply at "a" ...
. # # # O O . |
. . O O # # a |
. . . . . . . |
OR:
. . . . . . . |
. . . . # . . | ( with one line removed )
. . . . # O . |
. . . , # O . | White plays simply at "a" ...
. # # # O O . |
. . O O # # a |
. . . . . . . |
- regards
- jb
------------------------------------------------------------------------
Noise From Cell Phone Can Chase Mosquitoes
http://www.washingtonpost.com/wp-dyn/articles/A37000-2003Jul10.html
------------------------------------------------------------------------
-
From: Mark Space <mark_s...@hotmail.com>
> I think Nick Wedd got it right (thanks for the explaination btw).
>>> Mark Space <mark_s...@hotmail.com> writes
>>>>
>>>> looks alive to me:
>>>>
>>>> . . . . . . . |
>>>> . . . . . . . |
>>>> . . . . . # # |
>>>> . . . . . # O b
>>>> . . . . , # O |
>>>> . . # # # O O c
>>>> . . a O O # # #
>>>> --------O-O-O-+
>>>>
>>>> Black to play,
> BLACK to play, not white. Sure if white gets to make two moves
> in a row he can live easily, but that's not the case here. The
> position arises from the following problem: White to play and live.
>
> . . . . . . . |
> . . . . . . . |
> . . . . . # . |
> . . . . . # O |
> . . . . , # O |
> . . # # # O O |
> . . O O # # |
> --------------+
Yes, however I could not find -this- problem statement
in that cited James Davies reference, at p.81 ... :-)
> The answer given is:
> . . . . . . . |
> . . . . . . . |
> . . . . . # 4 |
> . . . . . # O |
> . . . . , # O |
> . . # # # O O |
> . . O O # # 2
> --------1-3-5-+
>
> So you can see it's plainly blacks turn at this point.
Ah, yes of course ... my bad, but from the incorrect diagram.
>> From: Nick Wedd <ni...@maproom.co.uk> ( Official BGA Representative )
>>
>>> Looks dead to me.
>>>
>>> If Black a White b, we have
>>>
>>> . . . . . . . |
>>> . . . . . . . |
>>> . . . . . # # |
>>> . . . . . # O O
>>> . . . . , # O |
>>> . . # # # O O |
>>> . . # O O # # #
>>> --------O-O-O-+
>>>
>>> then Black plays at T3, killing everything. Yes, if White could
>>> capture the four stones he would have a living shape,
> I think he was refering to "four stones" after B played T3, i.e. this
> position:
>
> . . . . . . . |
> . . . . . . . |
> . . . . . # # |
> . . . . . # O O
> . . . . , # O |
> . . # # # O O #
> . . # O O # # #
> --------O-O-O-+
>
> But he's right, white cannot put the four black stones in atari.
You got his position correct, but he's still not right.
There's no need for Black ("#") to play a bent-four. Black
can simply play from the outside and obtain a better position:
. . . . . . . |
. . . . . . . |
. . . . . # # #
. . . . . # O O
. . . . , # O |
. . # # # O O |
. . # O O # # #
--------O-O-O-+
- regards
- jb
-------------------------------------------------------------
Mathter of the Game, by Ilan Vardi
http://cf.geocities.com/ilanpi/dots.html
-------------------------------------------------------------
Chris Byler
>
>>> JR wrote:
>>>> Reading Tesuji by James Davies (3rd printing 1984), problem 3 p. 81
>>>> with the answer (p. 82) seems wrong to me: white win the capture
>>>> race, but to get a dead shape ... Is my view correct ?
>
>> Mark Space <mark_s...@hotmail.com> writes
>>> looks alive to me:
>>>
>>> . . . . . . . |
>>> . . . . . . . |
>>> . . . . . # # |
>>> . . . . . # O b
>>> . . . . , # O |
>>> . . # # # O O c
>>> . . a O O # # #
>>> --------O-O-O-+
>>>
>>> Black to play, but a and b are miai, yes? Then white c,
>>> or if black c white captures a living shape. Or did I err?
If a and b are miai, then if Black plays one White must play the other
(or sacrifice the miai). Taking one point of a miai is sente (unless
the opponent is willing to allow you to take both points in order to
play somewhere else).
Hmm?
The original situation listed _Black_ to move. A rather important
difference.
If Black takes one of 1 or 2, and White responds at a, Black can then
take 2 or 1. White dies.
If Black 1, White 2, then Black a kills the right side group (although
the bottom group might be able to escape, depending on the situation
on the rest of the board). If Black 2, White 1, Black a, then the
situation is as Nick describes: White cannot capture the four stone
group (the three in a line plus 'a') because he cannot safely put it
in atari. Black then extends to the intersection above 1 and kills.
Now, if _White_ is to move, you are correct as far as I can see.
Capturing at c will sacrifice the first miai (between 1 and 2) but
create a second (between the remaining point of 1 and 2 and the center
of the three-in-a-row). But that wasn't the question that was asked.
--
Chris Byler cby...@vt.edu
"Between justice and genocide there is, in the long run, no middle
ground." -- Lois McMaster Bujold (Aral Vorkosigan)
-
cby...@REMOVE-TO-REPLY.vt.edu (Chris Byler) wrote:
> [ ... ] The original situation listed _Black_ to move.
> A rather important difference. [ ... ]
You might be missing some interim posts from your newsreader.
Try a "google" search on the newsgroup, with this Subject: line.
We got as far as acknowledging that _Black_ was to move, however
that scenario for _Black_ to move did not arise from the James Davies
problem posed on p.81. Instead there was the (maybe) "typo" of some
missing line, or substracted stones, which rendered the solution diagram
different from the posed problem diagram. Then, Mr. Wedd's hypothesis
"an uncapturable bent-4" turned out to be a suboptimal solution system.
Playing from the outside was the obvious first-choice to select, therein.
- regards
- jb