The comb formation is alive. For the comb formation in the corner, dame is necessary. The carpenter's square becomes ko. If there is no stone on the handicap point, the carpenter's square is dead. There is death in the hane.
Strange things happen at the one-two points.
If a formation is symmetrical play at the center. Against three in a row, play right in the center. The enemy's key play is my own key play. The semeai where only one player has an eye is a fight over nothing. There are times when even a fight over nothing means something.