where the parentheses denote symmetrization, in a Lorentz transformation, primed spinors transform under the
conjugate of the transformation for unprimed ones, Einstein
summation is used throughout, and denotes the spinor connection,
which is equivalent to the Levi-Civita connection on Minkowski space. The zero
rest mass equation can be solved by twistor functions. The solution uses ideas
from complex variable theory and cohomology.