Normally black extends with
and white hanes and connects on the second line.The question is how to respond with white.
I was told this is an old joseki, and is playable for both. The old joseki was:
But recently I watched a Baduk TV program by Kim Seongryong on refuting trick plays, which considered
in the initial diagram to be a trick play. He suggests instead this as the best line for both, but black should use it only in special circumstances:
This seems much better for white than the old joseki. But what if black extends at
with 
?Kim says letting white play
is an insult from black, and after 
black trick has been refuted.My question is how should white answer
in the next diagram?In a game I played before watching this lecture I played as follows:
but the result doesn't seem bad for black, as white is undercut, and there's a peep in white's influence.
So it seems to me after having heard that
in the previous diagram refutes black's trick play that white ought to play 
:Probably
not best, but the point is white gets a kosumi and an atari which allows a knights move for the top white group to escape. And black's corner group still doesn't have two eyes. PS: this is my first post on 19x19, so please forgive me if the diagrams don't show up correctly!
, Black can't answer with 
because his position collapses. Black also can't cut at a. So I'd start with 
- there may be special situations, where this move is justified, though). You can find some first explanations in 