A 2-Modular Matrix Group Derived from Steiner Hexads

THE DERIVED GROUP OF A SEIFERT FIBRE GROUP

Every Seifert Fibre Group is the lift of a Fuchsian group to the universal covering group of PSL (2,R). From this, we work out a form of presentation for such a group. With the calculation of the Euler number, we can establish the presentation of the derived group of a Seifert Fibre Group

Solving group Steiner problems as Steiner problems

The generalized spanning tree or group Steiner problem (GSP) is a generalization of the Steiner problem in graphs (SPG): one requires a tree spanning (at least) one vertex of each subset, given in a family of vertex subsets, while minimizing the sum of the corresponding edge costs. Specialized solution procedures have been developed for this problem. In this paper we investigate the performance...

The Scattering Matrix for the Hilbert Modular Group

In this paper, we compute the scattering matrix for the Hilbert modular group over any number field K. We then express the determinant of the scattering matrix as a ratio of completed Dedekind zeta functions associated to the Hilbert class field of K. This generalizes work of Efrat and Sarnak [ES] in the imaginary quadratic case.

Linearly Derived Steiner Triple Systems

Admittance of rugate filters derived from a 2 × 2 inhomogeneous matrix.

Admittance diagrams are used to analyze qualitatively and quantitatively the behavior of inhomogeneous thin films with an arbitrary refractive-index function. From this study it follows that one can treat the behavior of rugate filters by using the concept of effective refractive indices, which are associated with the phase integral in a simple way. These results are applied to the study of per...