Null \(2\)-type surfaces in pseudo-Euclidean \(4\)-space with null mean curvature vector (Q2782755)

A submanifold \(M\) of a pseudo-Euclidean space \(E\) is called \(k\)-type if the position vector of \(M\) decomposes into \(k\) vector fields which are eigenvectors of the Laplacian of \(E\) with pairwise different eigenvalues. The authors derive a complete classification of the null 2-type surfaces in \(E=E^4_2\), where 4 denotes the dimension and 2 the signature, with null mean curvature vector.