Suzuki (2004) classified thin weakly distance-regular digraphs and proposed the project to classify weakly distance-regular digraphs of valency 3. The case of girth 2 was classified by the third author (2004) under the assumption of the commutativity. In this paper, we continue this project and classify these digraphs with girth more than 2 and two types of arcs.

Regular digraphs of degree d > 1, diameter k > 1 and order N(d, k) = d+· · ·+dk will be called almost Moore (d, k)-digraphs. So far, the problem of their existence has only been solved when d = 2, 3 or k = 2, 3. In this paper we prove that almost Moore digraphs of diameter 4 do not exist for any degree d.

Nonstandard digraphs and transfinite digraphs have been defined and examined in two prior technical reports. The present work examines digraphs that are both nonstandard and transfinite. This requires a combination in certain ways of the techniques used in the prior two works. We first construct herein nonstandard transfinite digraphs for all the naturalnumber ranks. Then, a special kind of non...

In this paper, we study two types of strong subgraph packing problems in digraphs, including internally disjoint problem and arc-disjoint problem. These can be viewed as generalizations the famous Steiner tree are closely related to arc decomposition We first prove NP-completeness for restricted symmetric digraphs Eulerian digraphs. Then get inapproximability results Finally digraph composition...

Two new domination parameters for a connected graph G: the weakly convex domination number of G and the convex domination number of G are introduced. Relations between these parameters and the other domination parameters are derived. In particular, we study for which cubic graphs the convex domination number equals the connected domination number.

Let $kgeq 1$ be an integer, and let $G$ be a graph. A {it$k$-rainbow dominating function} (or a {it $k$-RDF}) of $G$ is afunction $f$ from the vertex set $V(G)$ to the family of all subsetsof ${1,2,ldots ,k}$ such that for every $vin V(G)$ with$f(v)=emptyset $, the condition $bigcup_{uinN_{G}(v)}f(u)={1,2,ldots,k}$ is fulfilled, where $N_{G}(v)$ isthe open neighborhood of $v$. The {it weight} o...

Background: Prediction of adverse perinatal and postnatal outcomes could be possible by using ultrasound Doppler evaluation, however there are some controversies regarding this issue in the literature. The goal of present study was to evaluate predictive value of Doppler indices in single and twin pregnancies during second trimester. Materials and Methods: This prospective study was conducted i...

Gossiping is a problem of information dissemination described in a group of individuals connected by a communication network, where every individual in the network knows a unique item of information and needs to communicate it to everyone else. This communication pattern nds its main applications in the eld of interconnection networks for parallel and distributed architecture. Previous papers h...