Previous studies dealing with network theory focused mainly on the static aggregation of edges over specific time window lengths. Thus, most of the dynamic information gets lost. To assess the quality of such a static aggregation the temporal correlation coefficient can be calculated. It measures the overall possibility for an edge to persist between two consecutive snapshots. Up to now, this m...

The present research examined the effects of directed attention on speed of information transmission in the visual system. Ss judged the temporal order of 2 stimuli while directing attention toward 1 of the stimuli or away from both stimuli. Perception of temporal order was influenced by directed attention: Given equal onset times, the attended stimulus appeared to occur before the unattended s...

In this paper we study the problem of maintaining a single source shortest path tree or a breadth-rst search tree for a directed graph, in either an incremental or decremental setting. We maintain a single source shortest path tree of a directed graph G with unit edge weights during a sequence of edge deletions in total time O(mn), thus obtaining a O(n) amortized time for each deletion if the s...

The straight skeleton of a polygon is the geometric graph obtained by tracing the vertices during a mitered offsetting process. It is known that the straight skeleton of a simple polygon is a tree, and one can naturally derive directions on the edges of the tree from the propagation of the shrinking process. In this paper, we ask the reverse question: Given a tree with directed edges, can it be...

We present a polynomial time greedy algorithm that assigns proper wavelengths to a set of requests of maximum load L per directed ber link on a directed ber tree using at most 5=3L wavelengths. This improves previous results of 12, 10, 8, 9]. We also prove that no greedy algorithm can in general use less than 5=3L wavelengths for a set of requests of load L in a directed ber tree, and thus our ...

Given a directed graph G = (V, A), the Directed Maximum Leaf Spanning Tree problem asks to compute a directed spanning tree (i.e., an out-branching) with as many leaves as possible. By designing a Branch-and-Reduced algorithm combined with the Measure&Conquer technique for running time analysis, we show that the problem can be solved in time O(1.9043) using polynomial space. Hitherto, there hav...

We address the issue of eeciently assigning wavelengths to communication requests in wavelength division multiplexing (WDM) optical networks. We consider directed tree and tree of rings topologies. These are topologies of concrete practical relevance for which undirected underlying graph models have been studied by Raghavan and Upfal 6]. Directed models were rst studied by Mihail et al 4]. For ...

In this paper we introduce and study a directed tree problem motivated by a new graph product that we have recently introduced and analysed in two conference contributions in the context of periodic real-time processes. While the two conference papers were focussing more on the applications, here we mainly deal with the graph theoretical and computational complexity issues. We show that the dir...

Contrary to MON-tree index less than the temporal and spatial indexing methods based on road networks we proposed Improved-MON-tree. The index is divided into two levels and the quad tree grid index at the top of the road network, and the bottom of the two-dimensional Rtree index moving object moving information. In order to support the global trajectory of moving objects query, add a hash stru...