213WN notcher

213WN  

This is an unsettled critical notcher. Anything weaker is dead. a or b make life.

Black lives with a  

Playing a: after and , black can make life at either of the circled points.

Black lives with b  

lives as well: it makes two sure eyes at the circled points.

Demo  

( protects against capture)

213WN Failure  

is a mistake after -: White descends with to create shortage of liberties .After , White starts a ko for the life of this group. ^[1]

213WN  

Black must be careful after the sagari at . a is now the only way to live without ko.

Reading exercise  

An easy reading exercise, but Black has to be careful. How to answer the hane at ? See Beginner Exercise 280.