BQM 415

    Keywords: Question

(Moved from Message Board)


How about a page discussing the long L + 1 group? I think this group is unconditionally alive, but merits discussion since it could also easily result in ko or seki.

MrTenuki: Is this what you're talking about?


anonymousCoward: -Yes, that's it. Or maybe this as well:


I think it is probably common and merits some sequential analysis. Especially if there is already a descent on the outside.


Dieter: Since the long L group can be turned in a 1000 year ko only, it is to be expected that the extra leg provides life. The only remaining question seems to be whether White can rob the territory through seki. However, the lines at a and b separate the circled eyespaces and it is difficult to see how White can turned these into one eye or connect to the outside.

Maybe the original poster can suggest an attack and we can concentrate on refuting it?

MrTenuki (KGS 3k):


I've seen this sequence in my games before, as either side. Playing tenuki with B4 can be considered, but I don't see a way for Black to live unconditionally afterwards if B4 is played elsewhere, unless Black is willing to give up a few points.

B4 tenuki-- A ko?!  

If Black plays elsewhere with B4 and White replies with W5 as shown, this could happen if Black is bent on saving every stone. If B10 is played at a, W11 is played at B10, and the group dies. And B8 at W9 can be refuted by W9 at B8.

B4 tenuki, continuation (W9 at black+circle)  

But W5 above is actually a mistake, because Black can live by sacrificing a stone. This lives, albeit in gote.

B4 tenuki. Trying the 1-2 point...  

Tapir: I don't see a way for black to live without ko after W5. B6 at B8 will result in the same ko, imo. All other moves namely at W7 or a doesn't work, as far as i read.

Alternate attack


[ext] Eba shows this attack and defense.

--Bill Spight

BQM 415 last edited by Dieter on July 5, 2008 - 12:49
RecentChanges · StartingPoints · About
Edit page ·Search · Related · Page info · Latest diff
[Welcome to Sensei's Library!]
Search position
Page history
Latest page diff
Partner sites:
Go Teaching Ladder
Login / Prefs
Sensei's Library