A note on symmetric powers of the standard representation of .
Clique family inequalities a∑v∈W xv + (a - 1)∈v∈W, xv ≤ aδ form an intriguing class of valid inequalities for the stable set polytopes of all graphs. We prove firstly that their Chvátal-rank is at most a, which provides an alternative proof for the validity of clique family inequalities, involving only standard rounding arguments. Secondly, we strengthen the upper bound further and discuss consequences regarding the Chvátal-rank of subclasses of claw-free graphs.
The cubical dimension of a graph is the smallest dimension of a hypercube into which is embeddable as a subgraph. The conjecture of Havel (1984) claims that the cubical dimension of every balanced binary tree with vertices, , is . The 2-rooted complete binary tree of depth is obtained from two copies of the complete binary tree of depth by adding an edge linking their respective roots. In this paper, we determine the cubical dimension of trees obtained by subdividing twice a 2-rooted...
The nth-order determinant of a Toeplitz-Hessenberg matrix is expressed as a sum over the integer partitions of n. Many combinatorial identities involving integer partitions and multinomial coefficients can be generated using this formula.
If is a simple graph of size without isolated vertices and is its complement, we show that the domination numbers of and satisfy where is the minimum degree of vertices in .
For a graph , a double Roman dominating function is a function having the property that if , then the vertex must have at least two neighbors assigned under or one neighbor with , and if , then the vertex must have at least one neighbor with . The weight of a double Roman dominating function is the sum . The minimum weight of a double Roman dominating function on is called the double Roman domination number of and is denoted by . In this paper, we establish a new upper bound...