Let $ G $ be a simple graph with edge set $ E(G) $. The modified Sombor index is defined as $ ^{m}SO(G) = \sum\limits_{uv\in E(G)}\frac{1}{\sqrt{d_{u}^{2}~~+~~d_{v}^{2}}} $, where $ d_{u} $ (resp. $ d_{v} $) denotes the degree of vertex $ u $ (resp. $ v $). In this paper, we determine some bounds for the modified Sombor indices of graphs with given some parameters (e.g., maximum degree $ \Delta $, minimum degree $ \delta $, diameter $ d $, girth $ g $) and the Nordhaus-Gaddum-type results. We also obtain the relationship between modified Sombor index and some other indices. At last, we obtain some bounds for the modified spectral radius and energy.
Citation: Yufei Huang, Hechao Liu. Bounds of modified Sombor index, spectral radius and energy[J]. AIMS Mathematics, 2021, 6(10): 11263-11274. doi: 10.3934/math.2021653
Let $ G $ be a simple graph with edge set $ E(G) $. The modified Sombor index is defined as $ ^{m}SO(G) = \sum\limits_{uv\in E(G)}\frac{1}{\sqrt{d_{u}^{2}~~+~~d_{v}^{2}}} $, where $ d_{u} $ (resp. $ d_{v} $) denotes the degree of vertex $ u $ (resp. $ v $). In this paper, we determine some bounds for the modified Sombor indices of graphs with given some parameters (e.g., maximum degree $ \Delta $, minimum degree $ \delta $, diameter $ d $, girth $ g $) and the Nordhaus-Gaddum-type results. We also obtain the relationship between modified Sombor index and some other indices. At last, we obtain some bounds for the modified spectral radius and energy.
[1] | S. Alikhani, N. Ghanbari, Sombor index of polymers, MATCH Commun. Math. Comput. Chem., 86 (2021), 715-728. |
[2] | A. Ali, L. Zhong, I. Gutman, Harmonic index and its generalizations: Extremal results and bounds, MATCH Commun. Math. Comput. Chem., 81 (2019), 249-311. |
[3] | G. Arizmendi, O. Arizmendi, Energy of a graph and Randić index, Linear Algebra Appl., 609 (2021), 332-338. doi: 10.1016/j.laa.2020.09.025 |
[4] | J. A. Bondy, U. S. R. Murty, Graph Theory, New York: Springer, 2008. |
[5] | H. Chen, W. Li, J. Wang, Extremal values on the Sombor index of trees, MATCH Commun. Math. Comput. Chem., 87 (2022), in press. |
[6] | R. Cruza, I. Gutman, J. Rada, Sombor index of chemical graphs, Appl. Math. Comput., 399 (2021), 126018. |
[7] | G. Caporossi, I. Gutman, P. Hansen, L. Pavlović, Graphs with maximum connectivity index, Comput. Biol. Chem., 27 (2003), 85-90. doi: 10.1016/S0097-8485(02)00016-5 |
[8] | K. C. Das, S. Balachandran, I. Gutman, Inverse degree, Randić index and harmonic index of graphs, Appl. Anal. Discr. Math., 11 (2017), 304-313. doi: 10.2298/AADM1702304D |
[9] | K. C. Das, A. S. Cevik, I. N. Cangul, Y. Shang, On Sombor index, Symmetry, 13 (2021), 140. |
[10] | H. Deng, Z. Tang, R. Wu, Molecular trees with extremal values of Sombor indices, Int. J. Quantum. Chem., 121 (2021), e26622. |
[11] | S. Fajtlowicz, On conjectures of Graffiti-II, Congr. Numer., 60 (1987), 187-197. |
[12] | X. Fang, L. You, H. Liu, The expected values of Sombor indices in random hexagonal chains, phenylene chains and Sombor indices of some chemical graphs, Int. J. Quantum. Chem., 121 (2021), e26740. |
[13] | I. Gutman, Geometric approach to degree-based topological indices: Sombor indices, MATCH Commun. Math. Comput. Chem., 86 (2021), 11-16. |
[14] | I. Gutman, Some basic properties of Sombor indices, Open J. Discret. Appl. Math., 4 (2021), 1-3. |
[15] | I. Gutman, The energy of a graph, Berichte der Mathematisch-Statistischen Sektion im Forschungszentrum Graz, 103 (1978), 1-22. |
[16] | I. Gutman, S. Z. Firoozabadi, J. A. de la Pea, J. Rada, On the energy of regular graphs, MATCH Commun. Math. Comput. Chem., 57 (2007), 435-442. |
[17] | Y. Hong, A bound on the spectral radius of graphs, Linear Algebra Appl., 108 (1988), 135-140. doi: 10.1016/0024-3795(88)90183-8 |
[18] | B. Horoldagva, C. Xu, On Sombor index of graphs, MATCH Commun. Math. Comput. Chem., 86 (2021), 703-713. |
[19] | V. R. Kulli, I. Gutman, Computation of Sombor indices of certain networks, SSRG Int. J. Appl. Chem., 8 (2021), 1-5. |
[20] | J. Liu, On harmonic index and diameter of graphs, J. Appl. Math. Phy., 1 (2013), 5-6. |
[21] | H. Liu, H. Chen, Q. Xiao, X. Fang, Z. Tang, More on Sombor indices of chemical graphs and their applications to the boiling point of benzenoid hydrocarbons, Int. J. Quantum. Chem., 121 (2021), e26689. |
[22] | H. Liu, L. You, Y. Huang, Ordering chemical graphs by Sombor indices and its applications, MATCH Commun. Math. Comput. Chem., 87 (2022), in press. |
[23] | H. Liu, L. You, Y. Huang, Xiaona Fang, Spectral properties of p-Sombor matrices and beyond, arXiv: 2106.15362v1. |
[24] | H. Liu, L. You, Z. Tang, J. B. Liu, On the reduced Sombor index and its applications, MATCH Commun. Math. Comput. Chem., 86 (2021), 729-753. |
[25] | X. Li, Y. Shi, A survey on the Randić index, MATCH Commun. Math. Comput. Chem., 59 (2008), 127-156. |
[26] | F. F. Nezhad, M. Azari, T. Došlić, Sharp bounds on the inverse sum indeg index, Discr. Appl. Math., 217 (2017), 185-195. doi: 10.1016/j.dam.2016.09.014 |
[27] | M. Randić, On characterization of molecular branching, J. Amer. Chem. Soc., 97 (1975), 6609-6615. doi: 10.1021/ja00856a001 |
[28] | J. M. Rodríguez, J. M. Sigarreta, On the geometric-arithmetic index, MATCH Commun. Math. Comput. Chem., 74 (2015), 103-120. |
[29] | J. M. Rodríguez, J. M. Sigarreta, Spectral study of the geometric-arithmetic index, MATCH Commun. Math. Comput. Chem., 74 (2015), 121-135. |
[30] | D. Maji, G. Ghorai, A novel graph invariant: The third leap Zagreb index under several graph operations, Discrete Math., Algor. Applicat., 11 (2019), 1950054. doi: 10.1142/S179383091950054X |
[31] | D. Maji, G. Ghorai, Computing F-index, coindex and Zagreb polynomials of the kth generalized transformation graphs, Heliyon, 6 (2020), e05781. doi: 10.1016/j.heliyon.2020.e05781 |
[32] | I. Milovanović, E. Milovanović, M. Matejić, On some mathematical properties of Sombor indices, Bull. Int. Math. Virtual Inst., 11 (2021), 341-353. |
[33] | K. Pattabiraman, Inverse sum indeg index of graphs, AKCE Int. J. Graphs Comb., 15 (2018), 155-167. doi: 10.1016/j.akcej.2017.06.001 |
[34] | I. Redžepović, Chemical applicability of Sombor indices, J. Serb. Chem. Soc., 86 (2021), 445-457. doi: 10.2298/JSC201215006R |
[35] | T. Réti, T. Došlić, A. Ali, On the Sombor index of graphs, Contrib. Math., 3 (2021), 11-18. |
[36] | K. Sayehvand, M. Rostami, Further results on harmonic index and some new relations between harmonic index and other topological indices, J. Math. Comp. Sci., 11 (2014), 123-136. doi: 10.22436/jmcs.011.02.05 |
[37] | X. Xu, Relationships between harmonic index and other topological indices, Appl. Math. Sci., 6 (2012), 2013-2018. |
[38] | W. Zhang, L. You, H. Liu, Y. Huang, The expected values and variances for Sombor indices in a general random chain, Appl. Math. Comput., 411 (2021), 126521. |
[39] | L. Zhong, The harmonic index for graphs, Appl. Math. Lett., 25 (2012), 561-566. doi: 10.1016/j.aml.2011.09.059 |
[40] | L. Zhong, On the harmonic index and the girth for graphs, Roman. J. Inf. Sci. Tech., 16 (2013), 253-260. |
[41] | L. Zhong, K. Xu, Inequalities between vertex-degree-based topological indices, MATCH Commun. Math. Comput. Chem., 71 (2014), 627-642. |
[42] | B. Zhou, On the spectral radius of nonnegative matrices, Australas. J. Comb., 22 (2000), 301-306. |
[43] | B. Zhou, N. Trinajstić, On sum-connectivity matrix and sum-connectivity energy of (molecular) graphs, Acta Chim. Slov., 57 (2010), 518-523. |