Newton Polytopes of Tropical Polynomials

321 Views Asked by At

recently I've been reading about tropical polynomials and stumbled upon Andreas Gathmann's lecture notes.

In section 1.4, it is stated that a tropical polynomial in the form of

$$ g(x, y) = \max_i \{a_1^{(i)} x + a_2^{(i)} y \} $$

as a function depends on only the points $ (a_1^{(i)}, a_2^{(i)} )$ that are vertices of its Newton polygon $ \text{Newt}(g) = \text{conv}\{ (a_1^{(i)}, a_2^{(i)}) \} $

I can understand that this also generalizes to newton polytopes in higher dimensions, since all interior points will satisfy $ \mathbf{a}^T \mathbf{x} < \mathbf{a}_{k}^T \mathbf{x} $, where $\mathbf{a}_k$ is a vertex of the Newton Polytope.

What happens if $g$ also includes constant terms in its factors? E.g. if

$$ g(x, y) = \max_i \{ a_1^{(i)} x + a_2^{(i)} y + b_i \} $$

Can we incorporate in some way the constant terms in the Newton polytope construction to extend the above statement concerning the interior points?