In this paper, we apply techniques from the theory of ideals and varieties
in algebraic geometry to study the geometric structure of a properly posed
set of nodes (or PPSN, for short) for multivariate Lagrange interpolation a
long an algebraic hypersurface. We provide a hyperplane-superposition proce
ss to construct the PPSN for interpolation along an algebraic hypersurface,
and as a result, we offer a clear understanding of the geometric structure
of the PPSN for multivariate Lagrange interpolation in C-s.