The -de
Bruijn graph, for integers
and
, is the directed graph
whose vertices are the words of length
over an alphabet of
symbols. There is a directed
edge from one word to another when deleting the first symbol and appending one
symbol gives the second word. The graph has self-loops.
For example, the
-de
Bruijn graph is illustrated above.
The above figures show the first few -dimensional de Bruijn graphs on an alphabet
of
symbols for
.
The -de
Bruijn graph is implemented in the Wolfram
Language as DeBruijnGraph[m,
n].
The Fritsch graph is the underlying simple graph of the -de
Bruijn graph, obtained by forgetting edge directions and removing self-loops.
de Bruijn graphs are Eulerian and Hamiltonian. The -de
Bruijn graph has vertex count
, edge count
,
self-loops, directed graph
diameter
,
and indegree and outdegree
at every graph
vertex.
The independence numbers of the underlying simple graphs of the -de Bruijn graphs for
, 2, ... are 1, 2, 3, 7, 13, 28, ... (OEIS A006946).
For ,
the
-Kautz graph is obtained from the
-de Bruijn graph by removing the vertices
whose words contain two consecutive identical symbols (Bermond et al. 1986).