Gokyo Shumyo, Section 1, Problem 56 / Solution

Main line  

The first move is probably the hardest one. Why not 2-2 or 4-2 ? We'll investigate that later.

Variation  

If White enters at , Black closes the door with . Then seems to be the best move for White, but with and Black gets just enough eyespace. After , Black is alive - a and b are miai. (Disclaimer: there may be mistakes in this variation.)

Reference diagram  

White can enter Black's EyeSpace from two sides: at a or b. Black has to find a move which protects against both. Let's analyze some failures first.

Failure 1  

Simply closing off at is not good. makes miai of a and b.

Failure 2  

If Black closes off the other side, White breaks in from the first. Up to , Black makes a (slightly modified) door group which is dead.

Other candidates  

Here a and b also fail to protect against . So let's investigate the last candidate, c.

Failure 3  

here fails to protect against the jump to . His eye space is sufficiently reduced. The rest of the moves are for reference.

Variation 1  

If White plays or a, Black protects at and makes such nice shape that it isn't even necessary for Black to respond to . We'll analyze this in Gokyo Shumyo, Section 1, Derived Problem 56.