1,010 research outputs found
The k-metric dimension of a graph
As a generalization of the concept of a metric basis, this article introduces
the notion of -metric basis in graphs. Given a connected graph , a
set is said to be a -metric generator for if the elements
of any pair of different vertices of are distinguished by at least
elements of , i.e., for any two different vertices , there exist
at least vertices such that for every . A metric generator of minimum
cardinality is called a -metric basis and its cardinality the -metric
dimension of . A connected graph is -metric dimensional if is the
largest integer such that there exists a -metric basis for . We give a
necessary and sufficient condition for a graph to be -metric dimensional and
we obtain several results on the -metric dimension
Current Trends in Simheuristics: from smart transportation to agent-based simheuristics
Simheuristics extend metaheuristics by adding a
simulation layer that allows the optimization component to deal
efficiently with scenarios under uncertainty. This presentation
reviews both initial as well as recent applications of simheuristics,
mainly in the area of logistics and transportation. We also discuss
a novel agent-based simheuristic (ABSH) approach that combines simheuristic and multi-agent systems to efficiently solve stochastic combinatorial optimization problems. The presentation is based on papers [1], [2], and [3], which have been already accepted in the prestigious Winter Simulation Conference.Peer ReviewedPostprint (published version
Distribution planning in a weather-dependent scenario with stochastic travel times: a simheuristics approach
In real-life logistics, distribution plans might be affected by weather conditions (rain, snow, and fog), since they might have a significant effect on traveling times and, therefore, on total distribution costs. In this paper, the distribution problem is modeled as a multi-depot vehicle routing problem with stochastic traveling times. These traveling times are not only stochastic in nature but the specific probability distribution used to model them depends on the particular weather conditions on the delivery day. In order to solve the aforementioned problem, a simheuristic approach combining simulation within a biased-randomized heuristic framework is proposed. As the computational experiments will show, our simulation-optimization algorithm is able to provide high-quality solutions to this NP-hard problem in short computing times even for large-scale instances. From a managerial perspective, such a tool can be very useful in practical applications since it helps to increase the efficiency of the logistics and transportation operations.Peer ReviewedPostprint (published version
Distribution planning in a weather-dependent scenario with stochastic travel times: a simheuristics approach
In real-life logistics, distribution plans might be affected by weather conditions (rain, snow, and fog), since they might have a significant effect on traveling times and, therefore, on total distribution costs. In this paper, the distribution problem is modeled as a multi-depot vehicle routing problem with stochastic traveling times. These traveling times are not only stochastic in nature but the specific probability distribution used to model them depends on the particular weather conditions on the delivery day. In order to solve the aforementioned problem, a simheuristic approach combining simulation within a biased-randomized heuristic framework is proposed. As the computational experiments will show, our simulation-optimization algorithm is able to provide high-quality solutions to this NP-hard problem in short computing times even for large-scale instances. From a managerial perspective, such a tool can be very useful in practical applications since it helps to increase the efficiency of the logistics and transportation operations.Peer ReviewedPostprint (published version
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