Positive Plucker tree certificates for non-realizability

We introduce a new method for finding a non-realizability certificate of a simplicial sphere sigma: we exhibit a monomial combination of classical 3-term Plucker relations that yields a sum of products of determinants that are known to be positive in any realization of sigma; but their sum should vanish, contradiction. Using this technique, we prove for the first time the non-realizability of a balanced 2-neighborly 3-sphere constructed by Zheng, a family of highly neighborly centrally symmetric spheres constructed by Novik and Zheng, and several combinatorial prismatoids introduced by Criado and Santos. The method in fact works for orientable pseudo-manifolds, not just for spheres.

Automated summary

This article presents a new method for finding a non-realizability certificate of a simplicial sphere. It can be applied not only to balanced 2-neighborly 3-spheres, but also to orientable pseudo-manifolds.