For a simple graph $G$ with vertex set $V(G)=\{v_1,...,v_n\}$, we define the closed neighborhood set of a vertex $u$ as \\$N[u]=\{v \in V(G) \; | \; v \; \text{is adjacent to} \; u \; \text{or} \; v=u \}$ and the closed neighborhood matrix $N(G)$ as the matrix whose $i$th column is the characteristic vector of $N[v_i]$. We say a set $S$ is odd dominating if $N[u]\cap S$ is odd for all $u\in V(G)$. We prove that the parity of the cardinality of an odd dominating set of $G$ is equal to the parity of the rank of $G$, where rank of $G$ is defined as the dimension of the column space of $N(G)$. Using this result we prove several corollaries in one of which we obtain a general formula for the nullity of the join of graphs.
Primary Language | English |
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Subjects | Mathematical Sciences |
Journal Section | Research Articles |
Authors | |
Publication Date | December 30, 2022 |
Submission Date | December 30, 2021 |
Acceptance Date | June 2, 2022 |
Published in Issue | Year 2022 Volume: 71 Issue: 4 |
Communications Faculty of Sciences University of Ankara Series A1 Mathematics and Statistics.
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