Complex conjugation and simplicial algebraic hypersurfaces

Charles Arnal

Abstract: We call a real algebraic hypersurface in (C^*)^n simplicial if it is given by a real Laurent polynomial in n-variables that has exactly n+1 monomials with non-zero coefficients and such that the convex hull in Rn of the n+1 points of Zn corresponding to the exponents is a non-degenerate n-dimensional simplex. Such hypersurfaces are natural building blocks from which more complicated objects can be constructed, for example using O. Viro's Patchworking method. Drawing inspiration from related work by G. Kerr and I. Zharkov, we describe the action of the complex conjugation on the homology of the coamoebas of simplicial real algebraic hypersurfaces, hoping it might prove useful in a variety of problems related to topology of real algebraic varieties. In particular, assuming a reasonable conjecture, we identify the conditions under which such a hypersurface is Galois maximal.