In this paper, we investigate the computational complexity of subgraph reconfiguration problems in directed graphs. More specifically, focus on problem reconfiguring arborescences a digraph, where an arborescence is graph such that its underlying undirected forms tree and all vertices have in-degree at most 1. Given two goal to determine whether there (reconfiguration) sequence between given ea...

A deadlock-free multicast scheme called prefix multicasting in irregular networks is studied. In prefix routing, a compact routing table is associated with each node (processor). Basically, each outgoing channel of a node is assigned a special label and an outgoing channel is selected if its label is a prefix of the label of the destination node. Node and channel labeling in an irregular networ...

We study approaches for the exact solution of the NP–hard minimum spanning tree problem under conflict constraints. Given a graph G(V,E) and a set C ⊂ E ×E of conflicting edge pairs, the problem consists of finding a conflict-free minimum spanning tree, i.e. feasible solutions are allowed to include at most one of the edges from each pair in C. The problem was introduced recently in the literat...

To any positive contraction Q on `2(W ), there is associated a determinantal probability measure PQ on 2W , where W is a denumerable set. Let 0 be a countable sofic finitely generated group and G = (0, E) be a Cayley graph of 0. We show that if Q1 and Q2 are two 0-equivariant positive contractions on `2(0) or on `2(E) with Q1 ≤ Q2, then there exists a 0-invariant monotone coupling of the corres...