A stratified polyhedral homotopy method for sampling positive dimensional zero sets of polynomial systems

Abstract: Numerical algebraic geometry revolves around the study of solutions to polynomial systems via numerical method. The polyhedral homotopy of Huber and Sturmfels for computing isolated solutions and the concept of witness sets as numerical representations of non-isolated solution components, put forth by Sommese and Wampler, are two of the fundamental tools in this field. In this paper, we show that a modified polyhedral homotopy can reveal sample sets of non-isolated solution components, akin to witness sets, as by-products from the process of computing isolated solutions. In certain cases, this method also leads to a natural decomposition of the BKK bound into a sum of local contributions from individual irreducible components.