that for many scenarios, it is more meaningful to assign to each object a degree of being an outlier. This degree is called the local outlier factor (LOF) of an object. It is local in that the degree depends on how isolated the object is with respect to the surrounding neighborhood. We give a detailed formal

recognition, detection and clustering. The method is fast, does not require video alignment and is applicable in (but not limited to) many scenarios where the background is known. Moreover, we demonstrate the robustness of our method to partial occlusions, non-rigid deformations, significant changes in scale

Reliability at massive scale is one of the biggest challenges we face at Amazon.com, one of the largest e-commerce operations in the world; even the slightest outage has significant financial consequences and impacts customer trust. The Amazon.com platform, which provides services for many web

An ad hoc network is a collection of wireless computers (nodes), communicating among themselves over possibly multihop paths, without the help of any infrastructure such as base stations or access points. Although many previous ad hoc network routing protocols have been based in part on distance

mobile hosts. RPGM can be readily applied to many existing applications. Moreover, by proper choice of parameters, RPGM can be used to model several mobility models which were previously proposed. One of the main themes of this paper is to investigate the impact of the mobility model on the performance

Sensor networks are distributed event-based systems that differ from traditional communication networks in several ways: sensor networks have severe energy constraints, redundant low-rate data, and many-to-one flows. Datacentric mechanisms that perform in-network aggregation of data are needed

Location-based Access Control (LBAC) techniques allow the definition of users ’ access rights based on location predicates that exploit the users ’ physical location. However, evaluating the physical location of a user is a specialized activity that is unlikely to be performed by the same entity (e.g., organization or system) in charge of the access control decision. For this reason, location evaluation is usually assumed to be provided by specific Location Services (LSs) possibly coexisting in a same area and competing one with the others. In this paper, we address the issues related to the communication and negotiation between an Access Control Engine (ACE) enforcing access rules that include location-based predicates and multiple, functionally equivalent, LSs. We introduce metadata for the exchange of service level agreement attributes between the ACE and the LSs. Based on such metadata we develop different negotiation protocols, from a basic negotiation protocol that shows the core aspects of our proposal to an enhanced protocol that enriches the interaction by taking into account a cost/benefit analysis and some service requirements. Finally, we present an extension to the enhanced protocol to consider possible time validity constraints on access control decisions.

of models based on scenarios and finite sampling. Conditional value-at-risk is able to quantify dangers beyond value-at-risk, and moreover it is coherent. It provides optimization shortcuts which, through linear programming techniques, make practical many large-scale calculations that could otherwise be out

Many designs for integrated service networks offer a bounded delay packet delivery service to support real-time applications. To provide bounded delay service, networks must use admission control to regulate their load. Previous work on admission control mainly focused on algorithms that compute

.g., a human annotator). Active learning is well-motivated in many modern machine learning problems, where unlabeled data may be abundant but labels are difficult, time-consuming, or expensive to obtain. This report provides a general introduction to active learning and a survey of the literature