Spherical Coxeter groups and hyperelliptic 3-manifolds (Q1972515)

A 3-manifold \(M\) is called hyperelliptic if there exists an isometric involution \(\tau\) such that the quotient space \(M/\langle\tau\rangle\) is homeomorphic to the 3-sphere \(S^3\). Let \(X\) be one of the 3-dimensional geometries \(H^3\), \(E^3\), \(S^3\), \(H^2 \times E^1\), or \(S^2 \times E^1\), and let \(P\) be a Coxeter polyhedron (that is, each dihedral angle of \(P\) is of the form \(\pi/n\) for some integer \(n\)) in \(X\). Let \(\Delta(P)\) denote the group of isometries of \(X\) generated by reflections in the faces of \(P\). Under a condition relating \(P\) to some Coxeter polyhedron in \(S^3\), the authors show that \(\Delta(P)\) contains a torsion free, finite index subgroup \(G\) such that \(X^3/G\) is a hyperelliptic manifold. This result generalizes earlier work of the second author [Ann. Global Anal. Geom. 8, No. 1, 13-19 (1990; Zbl 0712.57007)].