Tsumego From Games 46 / Attempts

What's the best white shot at $$W?  

Black just played the marked stone... What's whites best attempt at saving his marked group? (Enjoy!;) Reuven

Possible starting moves:  

Tderz: Possible starting moves which come up to mind are:
White a, b, c, d and e.

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])

dia. [2]  

It looks like a miscalculation for Wc, but could be used as large scale attack on the black center group:

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.

dia. [4]  

Another variant seems to be in vain first ...
... black d and e (not f) seem miai ...

dia. [5]  

=, =

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.

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]

dia. [9]  

Not responding at a gives White tempo (sente) and avoids losing liberties:

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.

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?

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:

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.

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.

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

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 .

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?

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.

dia [21]  

... and keeping ko a to the last moment

dia [22]  

... after some ko threat by White

• - perhaps on the black center group with c,

but beware of the later ko at d, hence perhaps e see dia ^[24] ...

dia [23] ko  

... it became real ko against black.

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.

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 .

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.

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:

dia [32]: Dieter's question 1: Black hane  

1) How about Black's aggressive answer at ?

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.

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 !:

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.

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.

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.

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.

dia. [40] Black cuts off marked W  

Black cuts off marked

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?