To capture one side, cut the other side

"To capture one side, cut the other side" is a common principle in practical Go play. It means that, in the diagram above, if White has cutting points at A and B, Black must cut at A to capture the corner, and cut at B to capture the stone on the side. See the diagram below:

This principle not only applies to certain joseki but also frequently appears in middle-game battles. But have you ever thought about why this principle, "to capture one side, cut the other side," exists?

In this diagram, Black wants to capture the outside stone because this would leave White’s marked stone isolated and without support.

This is Black's ideal situation. Can White prevent it?

Theoretically, if White connects at 2, it can thwart Black's plan. So, is "to capture one side, cut the other side" just wishful thinking?

The answer is no. Although disrupting the opponent's plans and playing in the more valuable direction are important concepts, stone efficiency is the soul of Go! In most cases (especially in the early game), the principle "to capture one side, cut the other side" should be followed. Here, we first explain in words: the essence of "to capture one side, cut the other side" is to first sacrifice one stone and then capture another. In the above diagram, if White connects at 2, Black can capture a White stone without having to sacrifice anything, resulting in White losing a move locally. Next, we can analyze using the Tewari Method (Sequence rearranging).

In the lower right corner, Black plays a high approach, White responds with a low approach, and Black’s moves 2 and 4 form a joseki. Now, White has moves A and B, both standard responses. Here we will discuss White's move at B.

If Black plays 1 and White connects at 2...

Black 3 ladder, White counter-ladder at 4, and Black captures at 5.

Using the Tewari Method, we see that White originally should finish the joseki, but white tenuki and leave the main battlefield by playing big point at B.

Resulting to black block at 1, and making a very solid tiger mouth.

White 4 even sarcrifice a stone to black, leading to a considerable local loss for White.

If Black cuts at 1 and White connects on the outside instead of capturing, the loss is even greater...

Using the Move Split Method, it is equivalent to White playing an extension while Black secures the corner...

White 3 attach is not ideal, as black corner is greater than the komoku + knight move, making black more solid is not efficient.

White 7 is also slow.

White cut at 9 is also a significant loss, making Black’s corner extremely solid!

From the Tewari Method, we can see that "to capture one side, cut the other side" is almost an imperative move. If one does not capture a stone and connects instead, the efficiency of the stones is significantly different. We only consider alternative moves in special cases.。

For example, if Black cuts at A in this situation, White can connect to save the stones on the side and destroy Black’s large framework...

Connecting at O2 here is better than capturing.