Geometric and Combinatorial Structure of Hypersurface Coamoebas

Let V be a complex algebraic hypersurface de ned by a polynomial f with Newton polytope ∆. It is well known that the spine of its amoeba has a structure of a tropical hypersurface. We prove in this paper that there exists a complex tropical hypersurface V∞, f such that its coamoeba is homeomorphic to the closure in the real torus of the coamoeba of V . Moreover, the coamoeba of V∞, f contains an arrangement of (n− 1)-torus depending only on the geometry of ∆ and the coe cients of f . In addition, we can consider this arrangement, as a weighted codual hyperplanes arrangement in the universal covering of the real torus, and the balancing condition (the analogous to that of tropical hypersurfaces) is satis ed. This codual hyperplanes arrangement is called the shell of the complex coamoeba (the cousin of the spine of the complex amoeba). Using this combinatorial coamoebas structure, we show that the amoebas of complex algebraic hypersurfaces de ned by maximally sparse polynomials are solid. More precisely, we characterize the image of the order map de ned by Forsberg, Passare, and Tsikh.