Establishing frameworks - A complex example.

In this even game, only Black conforms to GCS. White 4 is an attempt to limit the expansion of the black framework. Judging this as no immediate threat to the one existing (notional) framework link, Black expands the framework on the other side. White 6 is a slightly dubious attack to sever a link.

At this point, some players might be tempted to abandon black 1 as a framework stone and establish a new framework stone instead. This would disobey the prime directive. Even though you might not yet appreciate why the prime directive works you are strongly advised to respect it! Black 7 correctly strengthens the weakest framework stone. So white 8 tries to run into the centre. Black 9 attacks the two white stones ostensibly to re-establish the link (shown on the diagram). But if White successfully resists, Black will instead gain more than adequate compensation from the influence of his surrounding stones. In particular, Black might aim at swallowing up white 4 to establish black territory on the left side of the board. Mindful of Black's plan, White switches the attack to the top right with white 10 (next diagram).

Continuation

The sequence that follows up to white 16 is joseki (optimal set sequence). But Black chose this particular joseki purely for the purpose of maintaining the framework stone and link. When asked about following joseki, one Japanese professional go player said "Study but do not follow joseki -you should just play the best move!" It is certainly a common error, even amongst amateur dan level players to play joseki by rote without sufficient regard for the overall position. Following GCS can cure this failing. Indeed, the GCS adherent can confidently diverge from joseki in order to comply with GCS directives.

The most instructive move in this opening is black 17. Many players would be tempted to play in the open corner. This would be perfectly respectable if following a territorial strategy but here would be inconsistent with the previous moves. Instead, after white 16, first here it is essential to identify the weakest framework stone. The push and cut through by White starting at
A does not work, so locally the corner framework stone is now relatively strong. In contrast, the centre framework stone to the left looks quite lonely, and the framework links on either side are both quite weak. To follow the prime directive, the simplest remedy is to add a stone at B. But instead, with black 17, Black chooses to help the weakest framework stone by proactively attacking the two white stones that are threatening the framework link to the left. Note that to play in the open corner now, would grab a few points of territory but hand the initiative to White in the urgent battle at the top.