CR singularities of real threefolds in C4

article abstract

CR singularities of real threefolds in C4 are classified by using
holomorphic coordinate changes to transform the quadratic part of the
real defining equations into one of a list of normal forms.  In the
non-degenerate case, it is shown that a real analytic manifold near a
CR singular point is formally equivalent to a real algebraic model.
Some degenerate cases also have this property.