TFG9 Black Upper Left

Starting situation  

First let's look at some simple questions... DaveSigaty

What if Black just connects?

Black connects  

Black has two liberties on the left while White has four at the top - White wins.

Hanging connection  

at

Again, Black has two liberties to White's four - White wins.

Something else  

at

If next Black a, White b, Black has only three liberties.

More serious 1  

This eliminates the opportunity for White to throw in here and squeeze Black. White plays to spoil Black's eye but when she answers with , Black sets up a ko for life on the left with the opportunity to capture White in the upper center still open. White can't win this way.

More serious 2a  

• is a strong play
• If , White answers with which threatens to cut at and at the same time reduces Black to one eye. If Black tries to cut at , White answers at . If Black persists with , sets ups a situation where Black is in shortage of liberties on both sides ( Black a, White b). White can capture the left side stones before Black can free himself at the top.

More serious 2b  

• Black varies to to prevent White from cutting at a.
• So White turns to the upper side to increase her liberties.

More serious 2c  

• forces
• So when White plays , the inner shapes are the same on both sides, but White is one move ahead, winning the fight and the game.

More serious 3  

If Black tries to prevent White's eye-spoiling move with , makes miai of the points marked a and b; so Black collapses. Note that playing at a lets Black make ko with a throw-in at .

More serious 2c - revised  

Continuing from 2b, Black plays instead of the original . When White throws in at , Black extends at . Although White takes the stone at , the space inside her group is much smaller than in the original line and she ends up with only five liberties. She has the ko but since the real issue is the survival of the black group on the left, Black has more ko threats than White.

More serious 2d - B lives!  

at . After , Black is two moves from capturing the white stones while on the left White is four moves away from capturing the black stones. Black also has the internal ko threats of a and b. White's position is hopeless.