Research Article

Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index

Volume: 28 Number: 2 July 31, 2026
TR EN

Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index

Abstract

Topological indices play a fundamental role in the study of graph structures and their quantitative properties, particularly in applications related to chemistry, network science, and dynamic system analysis. In this work, we study the Reduced Zagreb index, Zagreb coindices, and the PI index of monogenic semigroup graphs, a well-studied class of algebraic graphs with relevance to both pure and applied mathematics. Using the adjacency structure of the graph as the main tool, we derive exact closed-form expressions for these indices and illustrate the results through explicit examples. Furthermore, we obtain explicit parity-dependent closed-form formulas for the reduced first Zagreb index, reduced second Zagreb index, Zagreb coindices and the vertex-PI index of monogenic semigroup graphs. The derivations are based on a neighbourhood-block decomposition of the edge set, which provides a unified computational framework for several families of degree-based topological indices. These results demonstrate how the algebraic structure of a monogenic semigroup determines the behaviour of important graph-theoretical descriptors.

Keywords

Supporting Institution

This study has not received any financial or institutional support from any organization or project.

Ethical Statement

This study is a purely theoretical mathematics study and does not involve any human or animal subjects, personal data, surveys, interviews, or experimental procedures. Therefore, ethics committee approval is not required.

Thanks

The author declares that there are no specific individuals or institutions to acknowledge for this study.

References

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Details

Primary Language

English

Subjects

Algebra and Number Theory

Journal Section

Research Article

Publication Date

July 31, 2026

Submission Date

January 15, 2026

Acceptance Date

June 29, 2026

Published in Issue

Year 2026 Volume: 28 Number: 2

APA
Oğuz Ünal, S. (2026). Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 28(2), 958-980. https://doi.org/10.25092/baunfbed.1864110
AMA
1.Oğuz Ünal S. Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi. 2026;28(2):958-980. doi:10.25092/baunfbed.1864110
Chicago
Oğuz Ünal, Seda. 2026. “Degree-Based Topological Indices of Monogenic Semigroup Graphs: Reduced Zagreb Indices, Coindices and PI Index”. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi 28 (2): 958-80. https://doi.org/10.25092/baunfbed.1864110.
EndNote
Oğuz Ünal S (July 1, 2026) Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi 28 2 958–980.
IEEE
[1]S. Oğuz Ünal, “Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index”, Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi, vol. 28, no. 2, pp. 958–980, July 2026, doi: 10.25092/baunfbed.1864110.
ISNAD
Oğuz Ünal, Seda. “Degree-Based Topological Indices of Monogenic Semigroup Graphs: Reduced Zagreb Indices, Coindices and PI Index”. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi 28/2 (July 1, 2026): 958-980. https://doi.org/10.25092/baunfbed.1864110.
JAMA
1.Oğuz Ünal S. Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi. 2026;28:958–980.
MLA
Oğuz Ünal, Seda. “Degree-Based Topological Indices of Monogenic Semigroup Graphs: Reduced Zagreb Indices, Coindices and PI Index”. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi, vol. 28, no. 2, July 2026, pp. 958-80, doi:10.25092/baunfbed.1864110.
Vancouver
1.Seda Oğuz Ünal. Degree-based topological indices of monogenic semigroup graphs: reduced Zagreb indices, coindices and PI index. Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi. 2026 Jul. 1;28(2):958-80. doi:10.25092/baunfbed.1864110