# L+1 group

Difficulty: Intermediate   Keywords: Life & Death

An L+1 group is an L group with a leg. The leg can be at the short side or the long side of the L shape. In both cases the group lives or dies according to who plays first.

 Table of contentsFirst L+1 group First L+1 group, hane on one side First L+1 group, hane on both sides Second L+1 group Second L+1-group, hane one side Second L+1-group, hane on both sides Second L+1 group, weak leg

### First L+1 group

First L+1 group

The first L+1 group lives or dies according to who plays first.

Black lives

Black can live by playing on the 1-2 point as shown.

Seki. Black can play 'a' to get a ko.

Other possible defenses end up in ko or seki, depending on black's choice, as the next two diagrams show.

Same result.

White 2 is the only move. White 2 at the vital point fails to Black 2 at 4.

White kills

White can kill by playing hane at . This reduces the shape to the standard L group, which we already know is dead.

What now?

What happens if White plays on Blacks vital point? (Just thinking about "Your opponent's good move is your good move" does that apply here as well? I think Black is dead as well but am i correct?

White kills

Yes, white still can kill. After 7 - Bent four in the corner

### First L+1 group, hane on one side

First L+1 group, hane on one side

The extra hane gives a sense of security.

White cannot kill this way

The throw-in at no longer works: jumps and lives. If makes a placement, connects, and White cannot connect at a due to shortage of liberties, otherwise Black captures three to make an eye.

White kills

However, White can kill by the hane at followed by the placement at . tries to live, but forces , so makes a throw in and kills. Note the importance of the stone.

### First L+1 group, hane on both sides

First L+1 group, hane on both sides

The first L+1 group with hane on both sides is alive if it has an external liberty. However, when the group has no external liberties, White can turn it into a ten-thousand year ko.

Main line

The key tesuji here is .

Main line

The best moves by both players lead to a ten-thousand year ko.

Main line

Black can also get a multi step ko (for white) sequence, which should be better than ten-thousand year ko.

Main line

White must first win this ko in the corner...

Main line

Black can get rid of ko threats before continuing. If white wants to continue, he must play yet another ko to force the atari.

Main line

Only now does the real ko for the life of the corner start. Black usually should be able to win this or receive ample compensation elsewhere in the steps white took.

### Second L+1 group

Second L+1 group

If the leg is on the other side, again the position depends on who plays first.

Black lives

Now the 2-2 point is the vital point for Black.

White kills

Again, reducing Black to a basic L group by a hane, kills the corner.

### Second L+1-group, hane one side

Second L+1-group, hane one side

The hane at may seem to give some help in living.

White cannot kill this way

The throw-in at doesn't work anymore. Black lives with : White can not connect at a because Black can capture three to make an eye.

White kills

To kill, can go straight to the 2-2 point. After , Black is dead. See the addendum of the rectangular six in the corner page. Study: Would the marked White stone still be needed if the Black hane was at the top?

### Second L+1-group, hane on both sides

Problem

The two hane stones give some degree of security.

Solution

The attachment at leads to ko.

### Second L+1 group, weak leg

Second L+1 group

The second L+1 group with a weak leg is also unsettled. White can kill at a or Black can live by playing at a.