snakeeater on Go

Sunday, January 08, 2006

Solution to last month's (year's) problem

B-T18 allows black to live unconditionally. After B-T18,
white can only play R18 to avoid capture and prevent black
from forming any immediate eyes. B then responds with S18!
Now it's pretty clear B will be able to capture the R17 and R18
stones and form an additional eye at T19. W can try to put
up some resistance with Q19 thereafter, but B-P19 cuts W off.

A couple of notes on possible wrong moves. Capture at R18 by
black right away may look like the right move, but W would
immediately jump in at T18. B now can't play T17 after that
as if B did, W would play S18 to force B to fill R18, resulting
with just one eye.

Another possible sequence is: B-R18, W-T18, B-S18, W-T17. Now
B cannot make two eyes because the T19 eye possibility is gone and
B still have to cover Q18 somehow to make it a true eye. (Letting
W take Q18 later would result in a false eye at R17 for B!)

Tough problem, just shows how rich the possibility is at the corner.


  • At Mon Apr 03, 09:14:00 AM PDT, Anonymous Anonymous said…

    hey, a note about your solution:

    b-r18,w-t18, b s18, w t17 lives for black because he can then play p18 and get a second eye. Instead, when b plays s18, w has plays p18 and if b takes t17, w makes r17 a false eye and b can't get two eyes just from capturing t-18.


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