Ikken-tobi from a stretch

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)

If White tries to split ...  

Black is connected.

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.

A lost stone and white is strong  

Black cannot afford not to respond immediately.

The hidden empty triangle  

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

Cut prevented, white 5 laddered  

A reasonable response is .

Better influence  

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

Less influence  

A similar connection without as much influence around a.

Leads to a slightly better sequence  

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

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 pushes white back upward and leaves black with sente, black can then play at one of the points marked c to secure the connection.

Another possibility.  

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

Standard.  

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

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.