Black just played the marked stone... What's whites best attempt at saving his marked group? (Enjoy!;) Reuven
Tderz: Possible starting moves which come up to mind are:
White a, b, c, d and e.
![[Diagram]](../../diagrams/38/d6ba279b1787e5d33a806baf269ce4a1.png)
dia. [1]
Hence, Whites starts:
I see that a and b, are miai, the black corner has more fighting liberties than the 5 (now 4) white dame.
Continuing with a looks more promising:
(before screaming, look below [7]-[8])
![[Diagram]](../../diagrams/34/66d140c4c7b0fa3536bd9a7ae2102aad.png)
dia. [2]
It looks like a miscalculation for Wc, but could be used as
large scale attack on the black center group:
![[Diagram]](../../diagrams/9/f54b3fea4b9f8a13ff66cabd1611c737.png)
dia. [3]
yet White can continue with
or c and separate black's group.
Not a success for Black, got only some white stones
, but center group is cut-off and weak; the lower edge has a bad endgame.
![[Diagram]](../../diagrams/9/ad7c71d980215f73bb42f9b0f765a2e0.png)
dia. [6]
I think ,a is now futile because of b;
and starting with b does not work because of Bc, Wa, Bd and White has damezumari problems.
White e and f are also quite unrelated to the semeai below in this diagram.
![[Diagram]](../../diagrams/50/2577a1d3521c9587993b5bd4b97aba6f.png)
dia. [7]
at present dia. 1-3 look best, but comprise an error:
is answered by
-
and White has liberty problems.
Hence, one could try and leave out the liberty losing exchange
-
ind. [1]
![[Diagram]](../../diagrams/49/c8cf79ad1f062128bcbd88a894bbeb14.png)
dia. [10]
Now White considers playing h or b in order to destroy the eye-shape of the black center group, but that makes no sense as Black can connect at a or play i (if White a).
Hence , now coming back safely to White g and capturing the
is good enough.
![[Diagram]](../../diagrams/43/2f310936c25081c04d480876096904bc.png)
dia. [11]
After
Black must find the right moment to play a or i or perhaps first in the center around m.
Black a is big and honte and allows free play afterwards.
(Hope I didn't make stupid mistakes here)
Black ends in sente and could make later a good endgame around x to z for capturing
.
It is sente because White a, black r, white i does not attack much Black's center group (having the ko at k, an 1/2 eye at c and space around m).
Is this compromise the most likely outcome?
![[Diagram]](../../diagrams/5/2f0aaf30b9ee1def906cb0be04b601d1.png)
dia. [12] another variation
The shape among those
is also very suited for playing
.
(which is better? dia [11] or this [12]?).
Knowing that
itself is not important helps in the decision to sacrifice it:
![[Diagram]](../../diagrams/23/0fbbfffd2260fe867096a44ecb09e39b.png)
dia. [13] daydreaming - W's bubble bursts
If now White is squeezed
to
, then Black is connected on top
but the
are lost after
(not a, because Black would lose 2 stones after white b and the ko at c would only help White).
Already seeing this shape
-
-
tells us that White played inefficiently here.
White should look for better options.
![[Diagram]](../../diagrams/6/8a8518a15fa0973fa9dc1c759b389ac3.png)
dia. [14] similar to dias 5-6
Yet, similar to dias 5-6, White could try again
to
,
but again would fail after white miai of a and b.
![[Diagram]](../../diagrams/28/05dabed526ef6829322139d579ba18d6.png)
dia. [15] compromise
White could compromise with black via
to
.
This is a likely outcome. Both White and Black have connected their groups.
(if Wa, then Bb)
Black will lose territory in the endgame around the x-points
![[Diagram]](../../diagrams/28/eb02ecde206f80d1cf7cbd21b3ee7487.png)
dia [16]
In dia [1] I state something about the corner having more fighting liberties, but after 2nd thought, it does not seem so straightforward:
After
,
, Black must prohibit all connecting options to the left and takes away a liberty with
.
![[Diagram]](../../diagrams/20/3086f455f292af7e9fa5817ac0af49f0.png)
dia [17] common attacking point
The
have 4 liberties left, technically the corner can be killed easily (made nakade, common shape) by
but in exactly how many moves?
![[Diagram]](../../diagrams/34/db86171cdc00373f0d48850cb6afa8a9.png)
dia [19]
Black has a 4-nakade with (5-3=2) 2 liberties + the ko evolving at a + sente. If we deduct 1 liberty for the sente from White's 4 liberties, we guess it's 3 vs. 3 liberties in ko.
![[Diagram]](../../diagrams/15/ff88840b743bfa70779326b265ced802.png)
dia [22]
... after some ko threat by White
but beware of the later ko at d, hence perhaps e see dia [24] ...
![[Diagram]](../../diagrams/26/3a12d23343a7ceab02feb73412de1429.png)
dia [24] neglect ko threat on center group
Black neglects the ko threat on the center group,
because cutting is Gote for White and Black can start a new ko with
. White will have lost two fights and then perhaps the game.
![[Diagram]](../../diagrams/0/81649d9f6838cb29a0902d3c9847e661.png)
dia [25] peaceful by black?
See Dieter's variant below of this no-risk ko (dia. [24]) for black, starting with the descent at
(perhaps more stylish) and some moves later, eventually resulting in
.
![[Diagram]](../../diagrams/50/6dea2f777850cab171342549bf43b1b1.png)
Dieter's dia [26]: White can kill
Dieter: On the Long L-Group page, it is explained that the descent of
can kill Black, if Black prevents the connection. Here, we indeed have to care about White's external liberties.
![[Diagram]](../../diagrams/3/2b97c230fde9aef86b91b499b320c8c2.png)
Dieter's dia [27]: White can kill ?
unkx80's dia [28]: I don't know.
Although I wrote the relevant section of long L-group, I do not think the liberties allow. --unkx80
That's shocking news unkx80 :-) Tderz I should absorb your columns better.
![[Diagram]](../../diagrams/29/208d58ef03b02446b47640e6fec2ceba.png)
Dieter's dia [29]: White can kill ? (
@
,
ko))
![[Diagram]](../../diagrams/38/fafca91e29613e86eec5c0909381c32c.png)
Dieter's dia [30]: White can kill ? (
@
,
takes ko)
![[Diagram]](../../diagrams/10/7c3cb260c1e35e28fe5b4e895d5d4d29.png)
Dieter's dia [31]: Two move approach ko, White to play a threat
It's a two move approach ko for White. But two questions remain in my mind:
![[Diagram]](../../diagrams/14/d8fd5d00cbc81e42611c756cd22b2936.png)
dia [33]: Dieter's question 2: ko
starts a ko on the White group on a large scale. However, White seems to have a lot of internal threats. Still I think that Black may expect more of this than from the two move approach ko mentioned above.
![[Diagram]](../../diagrams/40/12a2be925fff63463a3195e29aaa1211.png)
reply to Dieter's question 2, dia [34]:
Tderz: reply to Dieter's question 2: ko?
First, it seems to me now that Dieter's sagari
is better technique (e.g. having a liberty more at a) than hane+connect, but I will check on this.
The ko
does not seem so effective, because the
have lost liberties and are therefore a source of many ko threats - if not
more !:
![[Diagram]](../../diagrams/42/9d090ef18b4dc03fe6dc9e3832e8d0e6.png)
reply to Dieter's question 2, dia [35]:
After
Black hardly wants to sacrifice the Black stone below
.
Besides that any of the previous white moves
-
could/should have been used for ko at
, a 2nd ko evolved, hence looking like double-ko.
Black can play c or d, I think it's similar.
![[Diagram]](../../diagrams/52/b2ee893ebcc87f8d9cb828601b596282.png)
reply to Dieter's question 2, dia [36]:
... afterwards, astonishingly a and b seem to lead to the same (German "Zugumkehrung" = move inversion?) good result for white - notice that this seems better than just double ko. In first instance, I preferred a.
![[Diagram]](../../diagrams/7/7f3919da8dc121256a97ed3d5d5611cf.png)
reply to Dieter's question 2, dia [37]:
White is already alive after
. The miai of m-n gives one eye at either o or p.
![[Diagram]](../../diagrams/37/bbd4389f16e85d4ad57071514fdff4cb.png)
reply to Dieter's question 2, dia [38]:
White could exchange
for
for separating (Black replies, after all it's big), then attack at
. Black would not answer White a at b (the 3 stones are useless now), rather escape making eye-shape around
=
or further.
Are we ready for conclusion?
Is unkx's dia [28], the simple sagari making miai of killing the corner or connection the simple & best answer to this problem?
Rich: Ummm... doesn't that diagram show white one liberty short of survival?
Tderz: true, simple sagari [32],[33] or hane [16] are ruled out by unkx's [28],
so it's diagrams [12] leading to compromise [15] ?unkx80: I still haven't studied this in detail... but I think diagram [17] may be still possible? Diagram [28] did not rule out [17].
Compromise dia [15] leads to a bad endgame on the lower side for black. Knowing that white in all variations seems able to connect somehow - and that also the connection of the black center group is at stake - Black should try to get sente and/or a good endgame on the lower side.
![[Diagram]](../../diagrams/21/5d3bd8f97076ce7b8ae297964fa424c7.png)
dia. [41]
White plays
here to avoid dia [40].
Black finds this result un-attractive, and might even prefer diagrams [8] to [11], where Black loses 7
(about 16 points, but white could lose
and black keeps the lower edge)), but in sente!
So, is dia [11] best for Black and therefore the fairest, most likely compromise?