This paper deals with the validation of topological maps of an environment by an active agent (such as a mobile robot), and the localization of an agent in a given map. The agent is assumed to have neither compass nor other instruments for measuring orientation or distance, and, therefore, no associated metrics. The topological maps considered are similar to conventional graphs. The robot is as...

The worst-case complexity of general decentralized POMDPs, which are equivalent to partially observable stochastic games (POSGs) is very high, both for the cooperative and competitive cases. Some reductions in complexity have been achieved by exploiting independence relations in some models. We show that these results are somewhat limited: when these independence assumptions are relaxed in very...

We present a new implementation of a widely used swap-based local search procedure for the p-median problem. It produces the same output as the best implementation described in the literature and has the same worst-case complexity, but, through the use of extra memory, it can be significantly faster in practice: speedups of up to three orders of magnitude were observed.

The worst-case complexity of an implementation of Quicksort depends on the random number generator that is used to select the pivot elements. In this paper we estimate the expected number of comparisons of Quicksort as a function in the entropy of the random source. We give upper and lower bounds and show that the expected number of comparisons increases from n log n to n, if the entropy of the...

We introduce a new number system that supports increments with a constant number of digit changes. We also give a simple method that extends any number system supporting increments to support decrements using the same number of digit changes. In the new number system the weight of the ith digit is 2−1, and hence we can implement a priority queue as a forest of heap-ordered complete binary trees...

Given a set of points S = {x1, . . . , xm} ⊂ R and > 0, we propose and analyze an algorithm for the problem of computing a (1 + )-approximation to the minimum-volume axis-aligned ellipsoid enclosing S . We establish that our algorithm is polynomial for fixed . In addition, the algorithm returns a small core set X ⊆ S , whose size is independent of the number of points m, with the property that ...

Our research focuses on formally bounded WCET analysis, where we aim to provide absolute guarantees on execution time bounds. In this paper, we describe how amortisation can be used to improve the quality of the results that are obtained from a fully-automatic and formally guaranteed WCET analysis, by delivering analysis results that are parameterised on specific input patterns and which take a...

In this paper we study the two-machine owshop scheduling problem with an availability constraint on the rst machine. We rst show that the worst-case error bound 2 of the heuristic provided by Lee [4] is tight. We then develop an improved heuristic with a worst-case error bound of 3 . c © 2000 Elsevier Science B.V. All rights reserved.

In program synthesis, we transform a specification into a program that is guaranteed to satisfy the specification. In synthesis of reactive systems, the environment in which the program operates may behave nondeterministically, e.g., by generating different sequences of inputs in different runs of the system. To satisfy the specification, the program needs to act so that the specification holds...