in this paper we give a 2-generator 2-relation presentation for the group sl(2,121). this proves that sl(2,121), the covering group of psl(2,121), is efficient

We consider definably compact groups in an o-minimal expansion of a real closed field. It is known that to each such group G is associated a natural exact sequence 1→ G00 → G → G/G00 → 1 where G00 is the “infinitesimal subgroup” of G and G/G00 is a compact real Lie group. We show that given a connected open subset U of G/G00 there is a canonical isomorphism between the fundamental group of U an...

The purpose of this paper is to generalize the relation [KM4] between intersection numbers of cycles in locally symmetric spaces of orthogonal type and Fourier coefficients of Siegel modular forms to the case where the cycles have local coefficients. Now the correspondence will involve vector-valued Siegel modular forms. Let V be a non-degenerate quadratic space of dimension m and signature (p,...

We propose a multilevel cooperative search algorithm to compute upper bounds for Cλ(v, k, t), the minimum number of blocks in a t − (v, k, λ) covering design. Multilevel cooperative search is a search heuristic combining cooperative search and multilevel search. We first introduce a coarsening strategy for the covering design problem which defines reduced forms of an original t − (v, k, λ) prob...

This paper considers the cycle covering of complete multipartite graphs motivated by the design of survivable WDM networks, where the requests are routed on sub-networks which are protected independently from each other. The problem can be stated as follows: for a given graph G, find a cycle covering of the edge set of ) (n Kt λ , where V( Kt (n))=V(G), such that each cycle in the covering sati...

In [V. Mathai, K-theory of twisted group C∗-algebras and positive scalar curvature, Contemp. Math. 231 (1999) 203–225], we established a natural connection between the Baum-Connes conjecture and noncommutative Bloch theory, viz., the spectral theory of projectively periodic elliptic operators on covering spaces. We elaborate on this connection here and provide significant evidence for a fundame...

A covering array CA(N ; t, k, v) is an N × k array such that every N × t sub-array contains all t-tuples from v symbols at least once, where t is the strength of the array. Covering arrays are used to generate software test suites to cover all t-sets of component interactions. The particular case when t = 2 (pairwise coverage) has been extensively studied, both to develop combinatorial construc...