Seize the opportunity to form a framework barrier

If you were playing the game depicted to the right, you would build up an understanding of the framework links move by move. Here we will have to analyse from scratch. (It is Black's turn to play.)

The black framework links
A-B, A-C, C-D are very strong and cannot be attacked. The remaining E-F link is secure but perhaps vulnerable to counterattack if White could peep into the black area from above.

The left side white group is predominantly a second line territorial invasion and has no strategic bearing on the game. The
J-L link is secure but the other white framework links demand careful examination ...

H-L

Black can, at least temporarily, break the H-L link. Black 3 is the best shot. (A similar sequence with black 3 above black 1 is also possible but with similar results.) But with white 6 three black stones are cut off. With the white wall at H and the white stone at K, the fight to kill white 6 looks dubious. Also, if white 6 lives, then some damage to the lower right black area would result. So the potential gains are not worth the risk. Hence, for the moment, the H-L link should be accepted as notional.

K-M

Black can also, at least temporarily, break the K-M link. In the sequence shown, White resists. The result of the fight is difficult to predict but Black is risking his lower territory and potentially considerably weakening the E-F link. This is not a good opportunity for Black - yet! The K-M link should also be treated as notional.

H-K

Black 1 is aimed at breaking the H-K link. But whilst threatening black 1, white 2 takes the opportunity to strengthen the K-M link. Black 3 completes the separation. This gives White the option of defending the H-L link or the G-K link. White 4 is much the better choice. Note that, if cut off, White can save the H framework stone by playing at P to gain two eyes.

So, due to the strengthening of two weak links, the judgement is that White has gained more than Black from the exchanges. However one link remains to be examined ...

G-K

Black 1 is aimed at a large gap. Combined with the black wall (to the left and up) this should intuitively feel plausible. Even so, it is hard work maintaining a barrier. Without black 3, Black would probably have to rely on winning a ko fight. With the black 3, white 4 exchange, Black can resist albeit with extreme caution. (The sequence after black 5 is illustrative only - White would probably bow to the inevitable and thus guard the corner instead.)

In this example the negation of a potential framework link is valid, but note that if White were any stronger in the region, such a direct attack would not be so effective.