Pierre Laroche

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This paper describes the Time Warp Operating System, under development for three years at the Jet Propulsion Laboratory for the Caltech Mark III Hypercube multi-processor. Its primary goal is concurrent execution of large, irregular discrete event simulations at maximum speed. It also supports any other distributed applications that are synchronized by(More)
In this paper, we present a new method to localize a mobile robot in dynamic environments. This method is based on places recognition, and a match between places recognized and the sequence of places that the mobile robot is able to see during a run from an initial place to an ending place. Our method gives a coarse idea of the robot's position and(More)
In this paper, we present a new tool for automatically solving Markov Decision Processes. Using a predefined partition of the MDP, a directed graph is built to decompose the global MDP into small local MDPs which are independently solved. An approximate solution for the global MDP is obtained using local solutions. Our approach has been tested on a mobile(More)
In this paper, we present two state aggregation methods, used to build stochastic plans, modelling our environment with Markov Decision Processes. Classical methods used to compute stochastic plans are highly untractable for problems necessiting a large number of states, like our robotics application. The use of aggregation techniques allows to reduce the(More)
In this paper, we consider the Robust Nurse Assignment Problem. This consists in finding the maximum number of absences of qualified nurses still permitting an optimal treatment of patients, leading us to the notion of critical jobs. We introduce the Bipartite Complete Matching Vertex Interdiction Problem as the graph formulation of this problem. We show(More)
The Job Shop Scheduling Problem is one of the most intractable NP-Hard combinatorial optimization problems. To solve optimally this problem in a reasonable computational time, we have to improve the lower and the upper bounds. In this paper we introduce a new lower bound to the job shop scheduling problem with min-sum criteria and compare two different(More)