An official website of the United States government
null
(Ed.)
The distance matrix $$\mathcal{D}(G)$$ of a graph $$G$$ is the matrix containing the pairwise distances between vertices, and the distance Laplacian matrix is $$\mathcal{D}^L (G)=T(G)-\mathcal{D} (G)$$, where $T(G)$ is the diagonal matrix of row sums of $$\mathcal{D}(G)$$. Several general methods are established for producing $$\mathcal{D}^L$$-cospectral graphs that can be used to construct infinite families. Examples are provided to show that various properties are not preserved by $$\mathcal{D}^L$$-cospectrality, including examples of $$\mathcal{D}^L$$-cospectral strongly regular and circulant graphs. It is established that the absolute values of coefficients of the distance Laplacian characteristic polynomial are decreasing, i.e., $$|\delta^L_{1}|\geq \cdots \geq |\delta^L_{n}|$$, where $$\delta^L_{k}$$ is the coefficient of $x^k$.
more »
« less
