Tropical Combinatorial Nullstellensatz and Sparse Polynomials

Abstract

Tropical algebra emerges in many fields of mathematics such as algebraic geometry, mathematical physics and combinatorial optimization. In part, its importance is related to the fact that it makes various parameters of mathematical objects computationally accessible. Tropical polynomials play a fundamental role in this, especially for the case of algebraic geometry. On the other hand, many algebraic questions behind tropical polynomials remain open. In this paper we address four basic questions on tropical polynomials closely related to their computational properties: 1. Given a polynomial with a certain support (set of monomials) and a (finite) set of inputs, when is it possible for the polynomial to vanish on all these inputs? 2. A more precise question, given a polynomial with a certain support and a (finite) set of inputs, how many roots can this polynomial have on this set of inputs? 3. Given an integer $k$, for which $s$ there is a set of $s$ inputs such that any non-zero polynomial with at most $k$ monomials has a non-root among these inputs? 4. How many integer roots can have a one variable polynomial given by a tropical algebraic circuit? In the classical algebra well-known results in the direction of these questions are Combinatorial Nullstellensatz due to N. Alon, J. Schwartz - R. Zippel Lemma and Universal Testing Set for sparse polynomials respectively. The classical analog of the last question is known as $τ$-conjecture due to M. Shub - S. Smale. In this paper we provide results on these four questions for tropical polynomials.