Black has four basic defending techniques:
a ) Defence from the rear (Cochrane)
b ) Double control of intersection (Szen)
c ) Sixth rank defence (Kling and Kuiper)
d ) Seventh rank defence (Schmidt) .
Defence from the rear (Cochrane) is convincingly the simplest, and based on tying the bishop on the fourth rank in order to prevent reaching the winning opposition with the black king on the eighth rank. A typical Cochrane position is presented in the following diagram. White to move cannot win, although he can manage to drive the competitor to the eighth rank.