Joseki-related life-and-death example 10

corner  

What is the best, black can do here

fist try (Klaus): seki  

is surely sente, but the seki is got for black (and white captured one stone). So If this is the best shot, we might count the white corner as (6+1):2= 3.5 points, right?

unkx80: How is at ?

%

Milo234

The above diagram is wrong, white can live uncondtionally with better points.

 

After 4 white is alive. black can't do anything else interesting to the shape now. Connecting below 1 is forcing.