Abstracto
- The form of the isometric, homothetic, and conformal Killing vectors for algebraically special metrics which admit a shear‐free congruence of null geodesics is obtained by considering their complexification, using the existence of a congruence of null strings. The Killing equations are partially integrated and the reasons which permit this reduction are exhibited. In the case where the congruence of null strings has a vanishing expansion, the Killing equations are reduced to a single master equation.