De Bruijn Isomorphisms and Free Space Optical Networks

The de Bruijn digraph Bd;D is usually defined by words of size D on an alphabet of cardinality d, through a cyclic left shift permutation on the words, after which the rightmost symbol is changed. In this paper, we show that any digraph defined on words and alphabets of the same size, through an arbitrary permutation on the alphabet and an arbitrary permutation on the word indices, is isomorphic to the de Bruijn, provided that this latter permutation is cyclic. As an application, we recall that it is known that the Optical Transpose Interconnection System from UCSD can implement the de Bruijn interconnections for n nodes, for a fixed d, with On lenses. We show here how to improve this hardware requirement to  pn.

• Type: Conference
• Year: 2000
• Where: IPPS
• Authors: David Coudert, Afonso Ferreira, Stephane Perennes
• Keywords: Arbitrary Permutation, Bruijn Digraph, Distributed And Parallel Computing, IPPS 2000, Left Shift Permutation