On the solvability of the Birkhoff interpolation problem Original Research Article

A univariate Birkhoff interpolation problem is considered and the smallest N, namely N̄, for which the Birkhoff interpolation problem is always solvable is given. In particular, for Pólya matrices E with n ones we obtain N̄⩽n+p, where p is the number of odd supported sequences in E, and show that the preceding bound is the best possible.