## Estrada Index of Graphs

**Authors:** Mohammed Kasim, Fumao Zhang, Qiang Wang

Suppose $G$ is a simple graph. The eigenvalues $\delta_1,
\delta_2,\ldots, \delta_n$ of $G$ are the eigenvalues of its
adjacency matrix $A$. The Estrada index of the graph $G$ is defined
as $EE = EE(G) = \Sigma_{i=1}^{n} e^{\delta_i}$. In this paper the
basic properties of $EE$ are investigated. Moreover, some lower and
upper bounds for the Estrada index in terms of the number of
vertices, edges and the Randic index are obtained. In addition, some
relations between $EE$ and graph energy $E(G)$ are presented.

**Comments:** 6 Pages.

**Download:** **PDF**

### Submission history

[v1] 2013-08-05 21:42:13

**Unique-IP document downloads:** 358 times

Vixra.org is a pre-print repository rather than a journal. Articles hosted may not yet have been verified by peer-review and should be treated as preliminary.
In particular, anything that appears to include financial or legal advice or proposed medical treatments should be treated with due caution.
Vixra.org will not be responsible for any consequences of actions that result from any form of use of any documents on this website.

**Add your own feedback and questions here:**

*You are equally welcome to be positive or negative about any paper but please be polite. If you are being critical you must mention at least one specific error, otherwise your comment will be deleted as unhelpful.*

*
*