invasion

A.k.a. uchikomi. A proponent invasion is defined as any play within an opponent dominated area where connection to established proponent stones outside the opponent's notional boundaries is not feasible. One technique is to settle the invading stones to give them independent life, but sometimes invading stones which cannot settle can 'run away' into the centre in anticipation of making life at some later stage. The timing of an invasion is critical. The invader must anticipate that the opponent will be able, in compensation, to form walls by threatening the vulnerable invading stones.

If, as is extremely common in games between kyu players, an invasion is made too early, the compensating walls, directly or indirectly, form more territory for the opponent than that seized.

Also, to be taken into account, is that invasions normally end in gote. However, the diagram shows a case ripe for invasion.The five unnumbered black stones dominate the quarter of the board, but the corner 4.4 point stone is vunerable to invasion at the 3.3 point. Here, the standard invasion sequence shown not only reduces Black's territory but does so in sente.