A set D of vertices a graph G=(V,E) is irredundant if each non-isolated vertex G[D] has neighbour in V−D that not adjacent to any other D. The upper irredundance number IR(G) the largest cardinality an G; IR(G)-set IR(G). IR-graph G IR(G)-sets as set, and sets D′ are only can be obtained from by exchanging single for D′. An IR-tree tree. We characterize IR-trees diameter 3 showing these graphs ...

The diameter of a tree is the largest number of edges on any path between two vertices in it. Given a weighted, connected, undirected graph G and a bound D ≥ 2, the bounded-diameter minimum spanning tree problem seeks a spanning tree on G of minimum weight whose diameter does not exceed D. An evolutionary algorithm for this NP-hard problem encodes candidate trees as permutations of their vertic...

background and objectives: phospholipases are a group of enzymes that breakdown phospholipid molecules producing second products. these second products play a diverse role in the cell such as signal transduction and digestion in humans. in this study, the effect of phospholipids on the expression of pld genes of a. fumigatus was investigated. the pld genes of this fungus were also investigated ...

Given a weighted undirected graph G=(V,E) with positive costs on the edges and a positive constant d, the min-degree constrained minimum spanning tree problem is to find a minimum cost spanning tree T of G where each node I of T either has degree at least d or is a leaf node. Thus, the goal is to find a spanning tree T where all its non-leaf nodes (or central nodes) have degree at least d. Thes...

We examine on-line heap construction and on-line permutation routing on trees under the matching model. Let T be and n-node tree of maximum degree d. By providing on-line algorithms we prove that: 1. For a rooted tree of height h, on-line heap construction can be completed within (2d − 1)h routing steps. 2. For an arbitrary tree, on-line permutation routing can be completed within 4dn routing s...

A long line of research on fixed parameter tractability integer programming culminated with showing that programs $n$ variables and a constraint matrix dual tree-depth $d$ largest entry $\Delta$ are solvable in time $g(d,\Delta){poly}(n)$ for some function $g$. However, the is not preserved by row operations, i.e., given program can be equivalent to another smaller tree-depth, thus does reflect...

We consider the problem of multiple sequence alignment under a xed evolu tionary tree given a tree whose leaves are labeled by sequences nd ancestral sequences to label its internal nodes so as to minimize the total length of the tree where the length of an edge is the edit distance between the sequences labeling its endpoints We present a new polynomial time approximation algorithm for this pr...

Avicennia marina (Avicenniaceae) is a species of mangrove tree used for treatment of small pox lesions in Persian folk medicine. The antiviral activity of methanol, ethanol, water, chloroform and n-hexane extracts was evaluated against HIV-1 and HSV. Methanol extract had the highest antiviral activity and the most polar fraction of this extract (fraction D) inhibited HSV with TI and SI values o...

We develop a modified willow tree algorithm for option pricing. Our numerical results show that it approximates the true prices more quickly and precisely than the binomial tree, especially in d-factor models for d = 2, 3, 4, 5. A bound on the theoretical rate of convergence of the modified willow tree algorithm is established.

A (pseudo-)metric D on a finite set X is said to be a ‘tree metric’ if there is a finite tree with leaf set X and nonnegative edge weights so that, for all x, y ∈ X , D(x, y) is the path distance in the tree between x and y. It is well known that not every metric is a tree metric. However, when some such tree exists, one can always find one whose interior edges have strictly positive edge weigh...