# L+1 Group / Leg on the Long Side

Sub-page of L1Group

Long L+1 group

A Long L+1 group is an L group with a leg at the long side.

A similar group exist with the leg at (the short side) this is then the /legontheshortside

If there are legs at both sides it is the L+2 group.

Both L+1 groups lives or dies according to who has sente.

Don't confuse the Long L+1 group with this group which is the Long L group.

Long L+1 group

The Long L+1 group lives or dies according to who has sente.

## Black to live

Black lives

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

## White to kill

### Standard kill

White kills

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

### Other kills

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?

### from the L+1 group / discussion

Black lives (1-2)

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

aLegendWai: Qs ^^: How about if B plays at another 1-2, 2-2? Will B live? If so, is it better than the first solution?

Black has problems (2-2)
Black lives smaller (2-2)

Black will live when they play at 2-2, but has a chance to run into trouble, and in general will get fewer points in the corner. If white hanes right away, black must play the vital point, not block. If black blocks, white can play the vital point instead, turning the corner (through a ko if black plays 1-1 first) into Bent Four in the Corner. When Black backs down and plays the vital point, they end with two points fewer in the corner. So, the 1-2 is the main line.

~Coconuts (7k)

Please correct me if I've gotten any of this wrong =).

Bill: As shown above, by playing on the 1-2 point Black secures two eyes, defensible under attack.

Seki or ko

on the 2-2 does not secure two eyes. White can continue to make seki or ko. (Here Black can still play at b to make ko, or he could have played at a, making ko that way.)

Best play depends on the circumstances, including ko threats. As a rule White can exploit Black's weaknessess after . In this case, for instance, White can start with , forcing . Black makes two eyes, but loses two points vs. playing one the 1-2 initially.

aLegendWai: In fact, it seems playing at either 1-2 point, or 2-2 point is alive in L+1 group.

Bill: See my later reply, above. Seki is life, but....

Generally speaking (not just limited to this case), when we decide which is the best move, what factors do we need to consider?

Any others?

Edge hane

Chris Hayashida: Edge hane aren't alive.

After , Black is dead. a and b are miai.

Edge hane #2

Chris Hayashida: Again, after , a and b are miai. Black is dead. Edge hanes don't make life.

aLegendWai: Thanks for telling.

this way kills?

zinger: Can white kill black regardless of the marked stone with the 2-1 placement?

unkx80: Well, depends on whether Black can get the hane at a in sente.

## Hane on one side =

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.

## Hane on both sides

Hane on both sides

With a 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.

# From corner shapes

## L groups

As it is, this is the L group. (The internal area is 2 by 3 points.) It is dead as it stands.

If is Black, then it is a Short L+1 group, and white can kill it, or black can live.

Also if is Black, then it is a long L+1 group?, and white can kill it, or black can live.

If both and are Black, then it is a L+2 group, and it is alive as it stands.

if both and are Black and is White, then it is a L+2 group with descent, white can make a approach ko or seki.

Long L group (the internal area is 2 by 4 points, whereas in the L group it is 2 by 3 points.)

If this group has no outside liberties, white can create a ten thousand year ko. If it has at least one outside liberty, white can make seki.

Note: If both legs are extended to the sides it is a Rectangular Eight In The Corner

Long L+1 group

A Long L+1 group is an L group with a legat the long side.

A similar group exist with the leg at (the other side) this is then the /legontheshortside

If there are legs at both sides it is the L+2 group.

Both L+1 groups lives or dies according to who has sente.

Don't confuse this group with the Long L group.

## Long L+1 group

Long L+1 group

If the leg is on the other side, again the position depends on who has sente.

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.

## Hane on one side

Hane on one side

The hane at may 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. As before, the stone is important.

## Hane on both sides

Problem

The two hane stones give some degree of security.

Solution

The attachment at leads to ko.

## Weak leg

Weak leg

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