Inspection games for selfish network environments

Current distributed information system consider only typical fault-tolerance techniques for re-liability issues. Selfish peers, which deviate from the collaborative protocol to increase personal benefit, may also harmfully affect the goals of networked architectures. Securing the collaborative protocol would be an option, however, this may not be always possible or wanted. Then, a post-hoc assessment, deployed by the system designer, could monitor the correct behaviour of the participants without affecting the actual system\u2019s functioning. Due to limited resources, a complete monitoring is not possible: typically monitoring is done by sampling by sampling so that misbehaviour in some case can go undetected. At the same time, a selfish peer\u2019s decision to violate also depends also on the monitoring rate of the inspecting parties. This forms an interdependent interaction landscape, which corresponds to a class of games known as Inspection Games. In this paper, we discuss the practicability of Inspection Games for networked architectures for system analysis and design. To this end, develop generalized Inspection Game versions up to m inspectors and n inspectees, starting from a simple two-player game; we further provide solutions (i.e. Nash equilibria) for all games. Afterwards, these games and solutions are adapted towards an application to networked architectures. This is done by extending them to the possibility of false negatives (the performed inspection on a player\u2019s behaviour does not detect a deviation from the protocol which has actually occurred, due to the intrinsic failability of the inspection technique)

A delay and cost balancing protocol for message routing in mobile delay tolerant networks

The increasing pervasiveness of mobile devices with networking capabilities has led to the emergence of Mobile Delay Tolerant Networks (MDTNs). The characteristics of MDTNs, which include frequent and long-term partitions, make message routing a major challenge in these networks. Most of the existing routing protocols either allocate an unlimited number of message copies or use a xed number of message copies to route a message towards its destination. While the first approach unnecessarily oods the network, the rigidity of the second approach makes it ine cient from the viewpoint of message replication. Hence, the question that we address in this paper is: "How to dynamically allocate message copies in order to strike a balance between the delay and cost of message delivery?". We present a novel adaptive multi-step routing protocol for MDTNs. In each routing step, our protocol reasons on the remaining time-tolive of the message in order to allocate the minimum number of copies necessary to achieve a given delivery probability. Experiment results demonstrate that our protocol has a higher delivery ratio and a lower delivery cost compared to the state-of-the-art Spray-and-Wait and Bubble protocols

ACCIO: How to Make Location Privacy Experimentation Open and Easy

The advent of mobile applications collecting and exploiting the location of users opens a number of privacy threats. To mitigate these privacy issues, several protection mechanisms have been proposed this last decade to protect users' location privacy. However, these protection mechanisms are usually implemented and evaluated in monolithic way, with heterogeneous tools and languages. Moreover, they are evaluated using different methodologies, metrics and datasets. This lack of standard makes the task of evaluating and comparing protection mechanisms particularly hard. In this paper, we present ACCIO, a unified framework to ease the design and evaluation of protection mechanisms. Thanks to its Domain Specific Language, ACCIO allows researchers and practitioners to define and deploy experiments in an intuitive way, as well as to easily collect and analyse the results. ACCIO already comes with several state-of-the-art protection mechanisms and a toolbox to manipulate mobility data. Finally, ACCIO is open and easily extensible with new evaluation metrics and protection mechanisms. This openness, combined with a description of experiments through a user-friendly DSL, makes ACCIO an appealing tool to reproduce and disseminate research results easier. In this paper, we present ACCIO's motivation and architecture, and demonstrate its capabilities through several use cases involving multiples metrics, state-of-the-art protection mechanisms, and two real-life mobility datasets collected in Beijing and in the San Francisco area

Antirheumatic drug therapy and its effects on cardiovascular health

Scholarly project (M.S.)

Query Load Balancing in Parallel Database Systems

International audienceDefinition : The goal of parallel query execution is minimizing query response time using inter- and intraoperator parallelism. Interoperator parallelism assigns different operators of a query execution plan to distinct (sets of) processors, while intraoperator parallelism uses several processors for the execution of a single operator, thanks to data partitioning. Conceptually, parallelizing a query amounts to divide the query work in small pieces or tasks assigned to different processors. The response time of a set of parallel tasks being that of the longest one, the main difficulty is to produce and execute these tasks such that the query load is evenly balanced within the processors. This is made more complex by the existence of dependencies between tasks (e.g., pipeline parallelism) and synchronizations points. Query load balancing relates to static and/or dynamic techniques and algorithms to balance the query load within the processors so that the response time is minimized