Totally Symmetric Functions are Reconstructible from Identification Minors

We formulate a reconstruction problem for functions of several arguments: Is a function of several arguments uniquely determined, up to equivalence, by its identification minors? We establish some positive and negative results on this reconstruction problem. In particular, we show that totally symmetric functions (of sufficiently large arity) are reconstructible.

Multivariate piecewise polynomials

This article was supposed to be on ‘multivariate splines». An informal survey, taken recently by asking various people in Approximation Theory what they consider to be a ‘multivariate spline’, resulted in the answer that a multivariate spline is a possibly smooth piecewise polynomial function of several arguments. In particular the potentially very useful thin-plate spline was thought to belong more to the subject of radial basis funtions than in the present article. This is all the more surprising to me since I am convinced that the variational approach to splines will play a much greater role in multivariate spline theory than it did or should have in the univariate theory. Still, as there is more than enough material for a survey of multivariate piecewise polynomials, this article is restricted to this topic, as is indicated by the (changed) title.