Indonesian Journal of Combinatorics
Vol 9, No 1 (2025)

On Coloring of Fractional Powers of Star, Wheel, Friendship, and Fan Graphs

Hafizh, Farisan (Combinatorics and Algebra Research Group, Department of Mathematics, Faculty of Mathematics & Natural Sciences, Universitas Indonesia)
Maulana, Muhammad Rayhanafraa Gibran (Combinatorics and Algebra Research Group, Department of Mathematics, Faculty of Mathematics & Natural Sciences, Universitas Indonesia)
Vienny, Citius (Combinatorics and Algebra Research Group, Department of Mathematics, Faculty of Mathematics & Natural Sciences, Universitas Indonesia)
Joyosumarto, Bisma Rohpanca (Combinatorics and Algebra Research Group, Department of Mathematics, Faculty of Mathematics & Natural Sciences, Universitas Indonesia)
Sugeng, Kiki A. (Combinatorics and Algebra Research Group, Department of Mathematics, Faculty of Mathematics & Natural Sciences, Universitas Indonesia)



Article Info

Publish Date
27 Jul 2025

Abstract

Let G be a simple, connected, and undirected graph. For m, n ∈ ℕ, the fractional power Gm/n = (G1/n)m of G is constructed by taking the n-subdivision of G (replacing each edge by a path of length n), and then raising the resulting graph to the m-th power (connecting any two distinct vertices with distance at most m).Let ω(G) be a clique number of G and χ(G) be the chromatic number of G. Iradmusa formulated a closed form for the clique number of Gm/n(ω(Gm/n)) and conjectured that χ(Gm/n) = ω(Gm/n) for every m, n ∈ ℕ where m/n < 1 and ∆(G) ≥ 3. The conjecture is true for certain special cases, such as paths, cycles and complete graphs. However, Hartke et. al. found a counterexample of the conjecture, that is the graph G = C3 ↆ K2 when m = 3 and n = 5. In this paper, we aim to prove that the conjecture is true for some classes of graphs that is not yet addressed. We prove that χ(Gm/n) = ω(Gm/n) for star, wheel, friendship, and fan graphs G.

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Journal Info

Abbrev

ijc

Publisher

Subject

Computer Science & IT Decision Sciences, Operations Research & Management

Description

Indonesian Journal of Combinatorics (IJC) publishes current research articles in any area of combinatorics and graph theory such as graph labelings, optimal network problems, metric dimension, graph coloring, rainbow connection and other related topics. IJC is published by the Indonesian ...