eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
0
0
10.4230/OASIcs.ATMOS.2015
article
OASIcs, Volume 48, ATMOS'15, Complete Volume
Italiano, Giuseppe F.
Schmidt, Marie
OASIcs, Volume 48, ATMOS'15, Complete Volume
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015/OASIcs.ATMOS.2015.pdf
Analysis of Algorithms and Problem Complexity, Optimization, Combinatorics, Graph Theory, Applications
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
i
x
10.4230/OASIcs.ATMOS.2015.i
article
Front Matter, Table of Contents, Preface, Organization
Italiano, Giuseppe F.
Schmidt, Marie
Front Matter, Table of Contents, Preface, Organization
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.i/OASIcs.ATMOS.2015.i.pdf
Front Matter
Table of Contents
Preface
Organization
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
1
15
10.4230/OASIcs.ATMOS.2015.1
article
Towards Realistic Pedestrian Route Planning
Andreev, Simeon
Dibbelt, Julian
Nöllenburg, Martin
Pajor, Thomas
Wagner, Dorothea
Pedestrian routing has its specific set of challenges, which are often neglected by state-of-the-art route planners. For instance, the lack of detailed sidewalk data and the inability to traverse plazas and parks in a natural way often leads to unappealing and suboptimal routes. In this work, we first propose to augment the network by generating sidewalks based on the street geometry and adding edges for routing over plazas and squares. Using this and further information, our query algorithm seamlessly handles node-to-node queries and queries whose origin or destination is an arbitrary location on a plaza or inside a park. Our experiments show that we are able to compute appealing pedestrian routes at negligible overhead over standard routing algorithms.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.1/OASIcs.ATMOS.2015.1.pdf
pedestrian routing
realistic model
shortest paths
speed-up technique
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
16
28
10.4230/OASIcs.ATMOS.2015.16
article
Speedups for Multi-Criteria Urban Bicycle Routing
Hrncir, Jan
Zilecky, Pavol
Song, Qing
Jakob, Michal
Increasing the adoption of cycling is crucial for achieving more sustainable urban mobility. Navigating larger cities on a bike is, however, often challenging due to cities’ fragmented cycling infrastructure and/or complex terrain topology. Cyclists would thus benefit from intelligent route planning that would help them discover routes that best suit their transport needs and preferences. Because of the many factors cyclists consider in deciding their routes, employing multi-criteria route search is vital for properly accounting for cyclists’ route-choice criteria. Direct application of optimal multi-criteria route search algorithms is, however, not feasible due to their prohibitive computational complexity. In this paper, we therefore propose several heuristics for speeding up multi-criteria route search. We evaluate our method on a real-world cycleway network and show that speedups of up to four orders of magnitude over the standard multi-criteria label-setting algorithm are possible with a reasonable loss of solution quality. Our results make it possible to practically deploy bicycle route planners capable of producing high-quality route suggestions respecting multiple real-world route-choice criteria.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.16/OASIcs.ATMOS.2015.16.pdf
bicycle routing
multi-criteria shortest path
heuristic speedups
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
29
41
10.4230/OASIcs.ATMOS.2015.29
article
Routing of Electric Vehicles: Constrained Shortest Path Problems with Resource Recovering Nodes
Merting, Sören
Schwan, Christian
Strehler, Martin
We consider a constrained shortest path problem with the possibility to refill the resource at certain nodes. This problem is motivated by routing electric vehicles with a comparatively short cruising range due to the limited battery capacity. Thus, for longer distances the battery has to be recharged on the way. Furthermore, electric vehicles can recuperate energy during downhill drive. We extend the common constrained shortest path problem to arbitrary costs on edges and we allow regaining resources at the cost of higher travel time. We show that this yields not shortest paths but shortest walks that may contain an arbitrary number of cycles. We study the structure of optimal solutions and develop approximation algorithms for finding short walks under mild assumptions on charging functions. We also address a corresponding network flow problem that generalizes these walks.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.29/OASIcs.ATMOS.2015.29.pdf
routing of electric vehicles
constrained shortest paths
FPTAS
con- strained network flow
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
42
55
10.4230/OASIcs.ATMOS.2015.42
article
Heuristic Approaches to Minimize Tour Duration for the TSP with Multiple Time Windows
Paulsen, Niklas
Diedrich, Florian
Jansen, Klaus
We present heuristics to handle practical travelling salesman problems with multiple time windows per node, where the optimization goal is minimal tour duration, which is the time spent outside the depot node. We propose a dynamic programming approach which combines state labels by encoding intervals to handle the larger state space needed for this objective function. Our implementation is able to solve many practical instances in real-time and is used for heuristic search of near-optimal solutions for hard instances. In addition, we outline a hybrid genetic algorithm we implemented to cope with hard or unknown instances. Experimental evaluation proves the efficiency and suitability for practical use of our algorithms and even leads to improved upper bounds for yet unsolved instances from the literature.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.42/OASIcs.ATMOS.2015.42.pdf
TSPTW
minimum tour duration
dynamic programming
heuristics
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
56
67
10.4230/OASIcs.ATMOS.2015.56
article
Single Source Shortest Paths for All Flows with Integer Costs
Takaoka, Tadao
We consider a shortest path problem for a directed graph with edges labeled with a cost and a capacity. The problem is to push an unsplittable flow $f$ from a specified source to all other vertices with the minimum cost for all f values. Let G = (V, E) with |V| = n and |E| = m. If there are t different capacity values, we can solve the single source shortest path problem t times for all f in O(tm + tn log n) time, which is O(m^2) when t = m. We improve this time to O(min{t, cn}m + cn^2), which is less than O(cmn) if edge costs are non-negative integers bounded by c. Our algorithm performs better for denser graphs.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.56/OASIcs.ATMOS.2015.56.pdf
information sharing
shortest path problem for all flows
priority queue
limited edge cost
transportation network
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
68
81
10.4230/OASIcs.ATMOS.2015.68
article
Robust Routing in Urban Public Transportation: Evaluating Strategies that Learn From the Past
Böhmová, Katerina
Mihalák, Matúš
Neubert, Peggy
Pröger, Tobias
Widmayer, Peter
Given an urban public transportation network and historic delay information, we consider the problem of computing reliable journeys. We propose new algorithms based on our recently presented solution concept (Böhmová et al., ATMOS 2013), and perform an experimental evaluation using real-world delay data from Zürich, Switzerland. We compare these methods to natural approaches as well as to our recently proposed method which can also be used to measure typicality of past observations. Moreover, we demonstrate how this measure relates to the predictive quality of the individual methods. In particular, if the past observations are typical, then the learning-
based methods are able to produce solutions that perform well on typical days, even in the presence of large delays.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.68/OASIcs.ATMOS.2015.68.pdf
public transportation
route planning
robustness
optimization
experiments
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
82
94
10.4230/OASIcs.ATMOS.2015.82
article
Bi-directional Search for Robust Routes in Time-dependent Bi-criteria Road Networks
Mihalák, Matúš
Montanari, Sandro
Based on time-dependent travel times for N past days, we consider the computation of robust routes according to the min-max relative regret criterion. For this method we seek a path minimizing its maximum weight in any one of the N days, normalized by the weight of an optimum for the respective day. In order to speed-up this computationally demanding approach, we observe that its output belongs to the Pareto front of the network with time-dependent
multi-criteria edge weights. We adapt a well-known algorithm for computing Pareto fronts in time-dependent graphs and apply the bi-directional search technique to it. We also show how to parametrize this algorithm by a value K to compute a K-approximate Pareto front. An experimental evaluation for the cases N = 2 and N = 3 indicates a considerable speed-up of the bi-directional search over the uni-directional.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.82/OASIcs.ATMOS.2015.82.pdf
shortest path
time-dependent
bi-criteria
bi-directional search
min-max relative regret
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
95
96
10.4230/OASIcs.ATMOS.2015.95
article
A Mixed Integer Linear Program for the Rapid Transit Network Design Problem with Static Modal Competition (Short Paper)
Gutiérrez-Jarpa, Gabriel
Laporte, Gilbert
Marianov, Vladimir
Moccia, Luigi
We present a mixed integer linear program for the rapid transit network design problem with static modal competition. Previous discrete formulations cannot handle modal competition for realistic size instances because of the complexity of modeling alternatives for each flow in the network. We overcome this difficulty by exploiting a pre-assigned topological configuration. Results of a case study will be presented at the conference.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.95/OASIcs.ATMOS.2015.95.pdf
metro network design
multi-objective optimization
modal competition
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
97
110
10.4230/OASIcs.ATMOS.2015.97
article
Ordering Constraints in Time Expanded Networks for Train Timetabling Problems
Fischer, Frank
The task of the train timetabling problem is to find conflict free schedules for a set of trains with predefined routes in a railway network. This kind of problem has proven to be very challenging and numerous solution approaches have been proposed. One of the most successful approaches is based on time discretized network models. However, one of the major weaknesses of these models is that fractional solutions tend to change the order of trains along some track, which is not allowed for integer solutions, leading to poor relaxations. In this paper, we present an extension for these kind of models, which aims at overcoming these problems. By exploiting a configuration based formulation, we propose to extend the model with additional ordering constraints. These constraints enforce compatibility of orderings along a sequence of tracks and greatly improve the quality of the relaxations. We show in some promising preliminary computational experiments that our approach indeed helps to resolve many of the invalid overtaking problems of relaxations
for the standard models.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.97/OASIcs.ATMOS.2015.97.pdf
combinatorial optimization
train timetabling
Lagrangian relaxation
ordering constraints
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
111
129
10.4230/OASIcs.ATMOS.2015.111
article
Regional Search for the Resource Constrained Assignment Problem
Borndörfer, Ralf
Reuther, Markus
The resource constrained assignment problem (RCAP) is to find a minimal cost partition of the nodes of a directed graph into cycles such that a resource constraint is fulfilled. The RCAP has its roots in rolling stock rotation optimization where a railway timetable has to be covered by rotations, i.e., cycles. In that context, the resource constraint corresponds to maintenance constraints for rail vehicles. Moreover, the RCAP generalizes variants of the vehicle routing problem (VRP). The paper contributes an exact branch and bound algorithm for the RCAP and, primarily, a straightforward algorithmic concept that we call regional search (RS). As a symbiosis of a local and a global search algorithm, the result of an RS is a local optimum for a combinatorial optimization problem. In addition, the local optimum must be globally optimal as well if an instance of a problem relaxation is computed. In order to present the idea for a standardized setup we introduce an RS for binary programs. But the proper contribution of the paper is an RS that turns the Hungarian method into a powerful heuristic for the resource constrained assignment problem by utilizing the exact branch and bound. We present computational results for RCAP instances from an industrial cooperation with Deutsche Bahn Fernverkehr AG as well as for VRP instances from the literature. The results show that our RS provides a solution quality of 1.4 % average gap w.r.t. the best known solutions of a large test set. In addition, our branch and bound algorithm can solve many RCAP instances to proven optimality, e.g., almost all asymmetric traveling salesman and capacitated vehicle routing problems that we consider.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.111/OASIcs.ATMOS.2015.111.pdf
assignment problem
local search
branch and bound
rolling stock rota- tion problem
vehicle routing problem
eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Open Access Series in Informatics
2190-6807
2015-09-14
48
130
143
10.4230/OASIcs.ATMOS.2015.130
article
Approximation Algorithms for Mixed, Windy, and Capacitated Arc Routing Problems
van Bevern, René
Komusiewicz, Christian
Sorge, Manuel
We show that any alpha(n)-approximation algorithm for the n-vertex metric asymmetric Traveling Salesperson problem yields O(alpha(C))-approximation algorithms for various mixed, windy, and capacitated arc routing problems. Herein, C is the number of weakly-connected components in the subgraph induced by the positive-demand arcs, a number that can be expected to be small in applications. In conjunction with known results, we derive constant-factor approximations if C is in O(log n) and O(log(C)/log(log(C)))-approximations in general.
https://drops.dagstuhl.de/storage/01oasics/oasics-vol048_atmos2015/OASIcs.ATMOS.2015.130/OASIcs.ATMOS.2015.130.pdf
vehicle routing
transportation
Rural Postman
Chinese Postman
NP- hard problem
parameterized algorithm
combinatorial optimization