TY - JOUR
ID - 102512
TI - Some Results on Forgotten Topological Coindex
JO - Iranian Journal of Mathematical Chemistry
JA - IJMC
LA - en
SN - 2228-6489
AU - Azari, Mahdieh
AU - Falahati-Nezhed, Farzaneh
AD - Kazerun Branch, Islamic Azad University
AD - Safadasht Branch, Islamic Azad University
Y1 - 2019
PY - 2019
VL - 10
IS - 4
SP - 307
EP - 318
KW - vertex degree
KW - Bound
KW - graph invariant
DO - 10.22052/ijmc.2019.174722.1432
N2 - The forgotten topological coindex (also called Lanzhou index) is defined for a simple connected graph G as the sum of the terms du2+dv2 over all non-adjacent vertex pairs uv of G, where du denotes the degree of the vertex u in G. In this paper, we present some inequalities for the forgotten topological coindex in terms of some graph parameters such as the order, size, number of pendent vertices, minimal and maximal vertex degrees, and minimal non-pendent vertex degree. We also study the relation between this invariant and some well-known graph invariants such as the Zagreb indices and coindices, multiplicative Zagreb indices and coindices, Zagreb eccentricity indices, eccentric connectivity index and coindex, and total eccentricity. Exact formulae for computing the forgotten topological coindex of double graphs and extended double cover of a given graph are also proposed.
UR - https://ijmc.kashanu.ac.ir/article_102512.html
L1 - https://ijmc.kashanu.ac.ir/article_102512_f335e16389378c0cec788b4cc1719e46.pdf
ER -