Coamoeba and phase limit set of a plane in 3-space


    The closure of the coamoeba of the plane in (C*)3 with equation x+y+z+1=0 is the complement in the fundamental domain [-π,π]3 of the open zonotope generated by the four vectors (-π,0,0), (0,-π,0), (0,0,-π), and (π,π,π).
    The phase limit set of the plane has four components, each is a cylinder over the phase limit set of a line obtained by contracting one of the four coordinates/directions (-π,0,0), (0,-π,0), (0,0,-π), and (π,π,π) (x,y,z, and 1, respectively.)


Phase limit set as x→0


Phase limit set as y→0


Phase limit set as z→0


Phase limit set as 1→0
    These components of the phase limit set correspond to the four rays of the tropical variety (here a fan) of the plane. The union of (the closures of) these four components of the phase limit set is the (closure of) the coamoeba, and a general point of the coamoeba lies in exactly two of these phase limit sets.



Last modified: Mon Feb 27 13:49:50 KST 2017