A Note on Signed k-Submatching in Graphs

Abstract: Let $G$ be a graph of order $n$. For every $v\in V(G)$, let $E_G(v)$ denote the set of all edges incident with $v$. A signed $k$-submatching of $G$ is a function $f:E(G)\longrightarrow {-1,1}$, satisfying $f(E_G(v))\leq 1$ for at least $k$ vertices, where $f(S)=\sum_{e\in S}f(e)$, for each $ S\subseteq E(G)$. The maximum of the value of $f(E(G))$, taken over all signed $k$-submatching $f$ of $G$, is called the signed $k$-submatching number and is denoted by $\beta ^k_S(G)$. In this paper, we prove that for every graph $G$ of order $n$ and for any positive integer $k \leq n$, $\beta ^k_S (G) \geq n-k - \omega(G)$, where $w(G)$ is the number of components of $G$. This settles a conjecture proposed by Wang. Also, we present a formula for the computation of $\beta_S^n(G)$.