Wedge - Ignoring the Checking Extension

Shusaku-Ito  

In this game Shusaku-Ito Matsujiro from 1844, Black places more importance on the fight in the lower right than on extending on the upper side, after the checking extension White 2. Black 3 is, according to normal thinking, played at a.

Shusaku-Ito (continuation)  

Black continues with a framework plan at the bottom, rather than running out with b. How does one evaluate this?

• White has played two stones at the top, Black one - so is Black's aji there better than if White had a single stone there at the point of Black 1 in the first diagram?
• White made the exchange White 10 of the first diagram for Black 1 of the second diagram in order to take sente and return to the top. How helpful is this to Black in enclosing the lower side?

It seems that this makes a trade-off: some gain for White on the first point, a gain for Black on the second point.

Charles Matthews