This paper analyzes the number of nodes expanded by A * as a function of the accuracy of its heuristic estimates by treating the errors h * h as random variables whose distributions may vary over the nodes in the graph. Our model consists of an m -ary tree with unit branch costs and a unique goal state situated at a distance N from the root. Two results are established: (1) for any error distri...

Virtually all real-world networks are dynamical entities. In social networks, the propensity of nodes to engage in social interactions (activity) and their chances to be selected by active nodes (attractiveness) are heterogeneously distributed. Here, we present a time-varying network model where each node and the dynamical formation of ties are characterized by these two features. We study how ...

Browsing is a fundamental aspect of exploratory information-seeking. Associative browsing represents a common and intuitive set of exploratory strategies in which users step iteratively from familiar to novel bits of information. In this paper, we examine associative browsing as a strategy for bottom-up exploration of large, heterogeneous networks. We present Refinery, an interactive visualizat...

The inclusion of children in research gives rise to a difficult ethical question: What justifies children's research participation and exposure to research risks when they cannot provide informed consent? This question arises out of the tension between the moral requirement to obtain a subject's informed consent for research participation, on the one hand, and the limited capacity of most child...

2.1. The Professional Role of Epidemiologists 2.2. Minimizing Risks and Protecting the Welfare of Research Participants 2.3. Providing Benefits 2.4. Ensuring an Equitable Distribution of Risks and Benefits 2.5. Protecting Confidentiality and Privacy 2.6. Obtaining the Informed Consent of Participants 2.6.1. Elements of informed consent 2.6.2. Avoidance of manipulation or coercion 2.6.3. Conditi...

due to limitations in computing resources of mobile nodes, mobile ad-hoc networks (manets) are very fault-prone. so far, redundancy at different levels of the network has been considered an efficient strategy to enhance the fault-tolerance of networks. indeed, ad-hoc networks are extremely redundant; therefore, natural redundancy to fault tolerance enhancement has a great impact on the network ...

In recent years, wireless sensor networks have drawn great attention. This type of network is composed of a large number of sensor nodes which are able to sense, process and communicate. Besides, they are used in various fields such as emergency relief in disasters, monitoring the environment, military affairs and etc. Sensor nodes collect environmental data by using their sensors and send them...

The topological ordering algorithm sorts nodes of a directed graph such that the order of the tail of each arc is lower than the order of its head. In this paper, we introduce the notion of covering between nodes of a directed graph. Then, we apply the topological orderingalgorithm on graphs containing the covering nodes. We show that there exists a cut set withforward arcs in these...