Symmetry and separation of Dirac's operator and its extension

An earlier discussion (Cook, 1982) of the separation of Dirac's equation for the electron is reconsidered and extended in terms of the symmetry operations admitted by Dirac's operator. The reason for the limited possibilities of separation are clarified, as is the relation of the spin operator to the choice of the reference vierbein for the spinors. The discussion is extended to an equation for many bodies (Cook, 1986, 1987). (author). 9 refs