Ikken-tobi from a stretch

   
[Diagram]

Ikken-tobi from a stretch

This shape makes a 100% connection, eye-shape at a, and it is flexible, because at all times Black can decide to abandon either the lone stone, or the connected pair of stones.

(Liberties/stones ratio = 3; occurrence frequency = 6)

[Diagram]

If White tries to split ...

Black is connected.

[Diagram]

A weakness to the peep

However, ikken-tobi from a stretch can be considered inefficient. This inefficency is unclear until white plays at the point marked a.

[Diagram]

A lost stone and white is strong

Black cannot afford not to respond immediately.

[Diagram]

A successful cut for white

[Diagram]

The hidden empty triangle

If black responds by closing the gap, there is the inefficient empty triangle around a.

[Diagram]

Cut prevented, white 5 laddered

A reasonable response is B2.

[Diagram]

Better influence

While this is effective, nikken-tobi from a stretch gives better influence around a, and the same play is still effective.

[Diagram]

Same defense

[Diagram]

Less influence

A similar connection without as much influence around a.

[Diagram]

Leads to a slightly better sequence

This leads to a sequence that is more favorable to black. W1 only strengthens black.

[Diagram]

Best response: pressure the white stone.

Here are a few other possible responses to the peep at the ikken tobi from a stretch. This first is probably the best: black should pressure the white stone. However, this leaves bad aji for black at a, so black should ideally have more influence around b than white to play this move. Alternatively, if the sequence started by B2 pushes white back upward and leaves black with sente, black can then play at one of the points marked c to secure the connection.

[Diagram]

Another possibility.

Here is another possibility. White will not even play the sequence W3 - B6 if she knows what is good for her, but this response is generally too easy on white if she plays tenuki instead of W3.

[Diagram]

Standard.

B2 is standard. It provides the farthest-reaching influence of the mentioned possibilites, though it may also be too easy on white.

[Diagram]

Bamboo joint.

This option gives white no possible cut, but in the absence of strong white influence in the area, is overconcentrated and provides no other advantage to black.


This is a copy of the living page "Ikken-tobi from a stretch" at Sensei's Library.
(OC) 2016 the Authors, published under the OpenContent License V1.0.
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