Charles See also Joseki-related life-and-death example 2.
This is another shape often resulting from a 3-3 invasion.
Let's try a few attacks for White.
Black has to let go two stones, or ...
There is shortage of liberties to play a.
Fhayashi: Is this better?
Black lives, but White can make an endgame gain at a.
Bildstein:What's wrong with making the L+2 group?
(to be completed - feel free to add)
If white has the marked stone, for example because black threatened to connect an outside group here, the corner can now be killed.
--Bass