منابع مشابه
An extension of the Wedderburn-Artin Theorem
In this paper we give conditions under which a ring is isomorphic to a structural matrix ring over a division ring.
متن کاملAn improved finiteness theorem for graphical t-designs
We prove that there exist only "nitely many nontrivial graphical t-(v; k; ) designs when k 6 4t=3. This improves a previous result of Betten et al. (Discrete Math. 197/198 (1999) 83–109). c © 2001 Elsevier Science B.V. All rights reserved. We use the notation and terminology of [1] and assume that the reader is familiar with the concept of graphical t-designs [2]. All polynomials in this note a...
متن کاملAn existence theorem for some simple t-designs
Dehon, M., An existence theorem for some simple t-designs, Discrete Mathematics 90 (1991) 137-142. Let S’ be a simple S;(t, k, [) containing b’ blocks and let S be a, not necessarily simple, $(t, 1. u); we prove that if b”(A 1) < (:), then there exists a simple &,(t, k, v). We apply this result to prove the existence of a new infinite family of 5-designs derived from the Alltop’s family of 5-de...
متن کاملAn Extension Theorem for Terraces
We generalise an extension theorem for terraces for abelian groups to apply to nonabelian groups with a central subgroup isomorphic to the Klein 4-group V . We also give terraces for three of the non-abelian groups of order a multiple of 8 that have a cyclic subgroup of index 2 that may be used in the extension theorem. These results imply the existence of terraces for many groups that were not...
متن کاملAn excess theorem for spherical 2-designs
We give an excess theorem for spherical 2-designs. This theorem is a dual version of the spectral excess theorem for graphs, which gives a characterization of distance-regular graphs, among regular graphs in terms of the eigenvalues and the excess. Here we give a characterization of Q-polynomial association schemes among spherical 2-designs.
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2001
ISSN: 0012-365X
DOI: 10.1016/s0012-365x(00)00392-7