Errata
page 11: alpha(x) should read
(2q-1+x2)/(2q4)
instead of
(2q-1+x2)/(2q2);
correspondingly in the general solution.
page 12, end of section right before section 2: the term order
should satisfy
e1>e2>e0
instead of
e2>e1>e0;
correspondingly, this eliminates e1 and the
resulting polynomial is in terms of
e2 and e0
instead of
e1 and e0
(with coefficients unchanged).
page 18, Eq. (2.13): read
(1-qqi)Si
-qqiqj(qiqj-qn)
instead of
(1-qqi)qjSi
-qqi(qiqj-qn);
similarly for the operator in Sj.
page 23, definition of py: read 2x+4y
instead of 2x+2y.