On Laplacian Eigenvalues of Wheel Graphs

Consider G to be a simple graph with n vertices and m edges, and L(G) to be a Laplacian matrix with Laplacian eigenvalues of & mu;1,& mu;2, horizontal ellipsis ,& mu;n=zero. Write Sk(G)= n-ary sumation i=1k & mu;i as the sum of the k-largest Laplacian eigenvalues of G, where k & ISIN;{1,2, horizontal ellipsis ,n}. The motivation of this study is to solve a conjecture in algebraic graph theory for a special type of graph called a wheel graph. Brouwer's conjecture states that Sk(G)& LE;m+k+12, where k=1,2, horizontal ellipsis ,n. This paper proves Brouwer's conjecture for wheel graphs. It also provides an upper bound for the sum of the largest Laplacian eigenvalues for the wheel graph Wn+1, which provides a better approximation for this upper bound using Brouwer's conjecture and the Grone-Merris-Bai inequality. We study the symmetry of wheel graphs and recall an example of the symmetry group of Wn+1, n & GE;3. We obtain our results using majorization methods and illustrate our findings in tables, diagrams, and curves.