Department of Mathematics, Science Faculty, Selçuk University, 42075 Konya, Turkey
Copyright © 2010 A. Dilek Güngör. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We first define a new Laplacian spectrum based on Estrada index, namely,
Laplacian Estrada-like invariant, LEEL, and two new Estrada index-like quantities, denoted
by S and , respectively, that are generalized versions of the Estrada index. After that, we
obtain some lower and upper bounds for LEEL, S, and .