Double hane near a corner is dangerous
The first (and only) time I've been in a Go club a game between me and a 3d was set. He gave me 9 stones of handicap (for obvious reasons) and he ended up winning anyway. But there was a sequence where he was able to invade my corner, a corner which was 4x3, no more space available. I've kept that sequence in my mind in order to play it someday against my opponents.
Since noone wants to play ranked games against an unranked player, I was forced to use KGS' automatch feature, which game me a 3 stones handicap game against a 12k player. It's not that I'm not used to give stone handicap, but I can tell you I hadn't played Go this year, so I wasn't too confident about my reading ability.
Finally, at the end of the middlegame - beginning of the yose, my opponent happened to make a double-hane in the "right" place for me to try that sequence. See what happened here:
It is important to see that during the whole sequence everything is made on an atari basis or a major killing threat. The two first white moves are direct ataris, though sacrificing one single stone, while the third one (209) is a threat for the four black stones...
Once we have these three stones on the board with sente, we can play B1 in order to get one eye while the other one will come after black's attempt to kill W group.
In this case, I wasn't very convinced about playing white 213 at D2, which I definitelly should have done as it is worth a few points. This is the sort of reading mistakes I was afraid of when I started the game, but it all ended well.
How to avoid it?
First of all, don't make the double hane. Black should have given white one more point letting me enter till A3 and then Black should have haned...Once you are tricked and B2 is place on the board, there is only one remote possibility for you to kill black. Here you have the sequence:
The only way for black to kill white here is to transform the possible second eye into a false one by placing a stone and then escaping by the lowest line. If black had a stone at F1 which could be one possible way to make 216 survive, white would die. In this case, there isn't any black reinforcement, in fact, there is only a white one.
