Distance mean-regular graphs
We introduce the concept of distance mean-regular graph, which can be seen as a generalization of both vertex-transitive and distance-regular graphs. Let Γ be a graph with vertex set V , diameter D , adjacency matrix A , and adjacency algebra A . Then, Γ is distance mean-regular when, for a given u...
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| Veröffentlicht in: | Designs, codes, and cryptography Jg. 84; H. 1-2; S. 55 - 71 |
|---|---|
| Hauptverfasser: | , |
| Format: | Journal Article Verlag |
| Sprache: | Englisch |
| Veröffentlicht: |
New York
Springer US
01.07.2017
Springer Nature B.V |
| Schlagworte: | |
| ISSN: | 0925-1022, 1573-7586 |
| Online-Zugang: | Volltext |
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| Zusammenfassung: | We introduce the concept of distance mean-regular graph, which can be seen as a generalization of both vertex-transitive and distance-regular graphs. Let
Γ
be a graph with vertex set
V
, diameter
D
, adjacency matrix
A
, and adjacency algebra
A
. Then,
Γ
is
distance mean-regular
when, for a given
u
∈
V
, the averages of the intersection numbers
p
i
j
h
(
u
,
v
)
=
|
Γ
i
(
u
)
∩
Γ
j
(
v
)
|
(number of vertices at distance
i
from
u
and distance
j
from
v
) computed over all vertices
v
at a given distance
h
∈
{
0
,
1
,
…
,
D
}
from
u
, do not depend on
u
. In this work we study some properties and characterizations of these graphs. For instance, it is shown that a distance mean-regular graph is always distance degree-regular, and we give a condition for the converse to be also true. Some algebraic and spectral properties of distance mean-regular graphs are also investigated. We show that, for distance mean regular-graphs, the role of the distance matrices of distance-regular graphs is played for the so-called distance mean-regular matrices. These matrices are computed from a sequence of orthogonal polynomials evaluated at the adjacency matrix of
Γ
and, hence, they generate a subalgebra of
A
. Some other algebras associated to distance mean-regular graphs are also characterized. |
|---|---|
| Bibliographie: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
| ISSN: | 0925-1022 1573-7586 |
| DOI: | 10.1007/s10623-016-0208-5 |