Halfedge * ELleft(Halfedge *)
void ELdelete(Halfedge *)
Site * leftreg(Halfedge *)
Site * rightreg(Halfedge *)
Site * hintersect(Halfedge *, Halfedge *)
Halfedge * HEcreate(Edge *, char)
Halfedge * ELright(Halfedge *)
Halfedge * ELleftbnd(Point *)
void ELinsert(Halfedge *, Halfedge *)
int right_of(Halfedge *, Point *)
struct Halfedge * ELright