On the Total Vertex-irregular Strength of a Disjoint Union of \(t\) Copies of a Path

Nurdin 1,2, A.N.M. Salman1, N.N. Gaos1, E.T. Baskoro1
1Combinatorial Mathematics Research Group, Faculty of Mathematics and Natural Sciences Institut. Teknologi Bandung (ITB) Jalan Ganesha No. 10 Bandung 40132, Indonesia
2Mathematics Department, Faculty of Mathematics and Natural Sciences, Hasanuddin University (Universitas Hasanuddin), Jl. Perintis Kemerdekaan Km 10 Tamalanrea, Makassar, Indonesia

Abstract

For a simple graph \( G \) with the vertex set \( V \) and the edge set \( E \), a labeling \( \lambda: V \cup E \to \{1, 2, 3, \ldots, k\} \) is called a vertex-irregular total \( k \)-labeling of \( G \) if for any two different vertices \( x \) and \( y \) in \( V \) we have \( wt(x) \neq wt(y) \), where \( wt(x) = \lambda(x) + \sum_{xy \in E} \lambda(xy) \).

The total vertex-irregular strength, denoted by \( tvs(G) \), is the smallest positive integer \( k \) for which \( G \) has a vertex-irregular total \( k \)-labeling. In this paper, we determine the total vertex-irregular strength of a disjoint union of \( t \) copies of a path, denoted by \( tP_n \). We prove that for any \( t \geq 2 \),

\[
tvs(tP_n) =
\begin{cases}
t & \text{for } n = 1, \\
t+1 & \text{for } 2 \leq n \leq 3, \\
\lceil \frac{nt+1}{3} \rceil & \text{for } n \geq 4.
\end{cases}
\]

Keywords: path, total k-labeling, total vertex-irregular strength