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- research-articleDecember 2023
VRPSolverEasy: A Python Library for the Exact Solution of a Rich Vehicle Routing Problem
INFORMS Journal on Computing (INFORMS-IJOC), Volume 36, Issue 4Pages 956–965https://doi.org/10.1287/ijoc.2023.0103The optimization community has made significant progress in solving vehicle routing problems (VRPs) to optimality using sophisticated branch-cut-and-price (BCP) algorithms. VRPSolver is a BCP algorithm with excellent performance in many VRP variants. ...
- ArticleDecember 2023
Two Exact Algorithms for the Packet Scheduling Problem
Combinatorial Optimization and ApplicationsPages 141–153https://doi.org/10.1007/978-3-031-49611-0_10AbstractWe consider a classic packet scheduling problem [7] and its variants. This packet scheduling problem has applications in the areas of logistics, road traffic, and more. There is a network and a set of unit-length packets are to be transmitted over ...
- research-articleNovember 2023
Efficient Maximum k-Defective Clique Computation with Improved Time Complexity
Proceedings of the ACM on Management of Data (PACMMOD), Volume 1, Issue 3Article No.: 209, Pages 1–26https://doi.org/10.1145/3617313k-defective cliques relax cliques by allowing up-to k missing edges from being a complete graph. This relaxation enables us to find larger near-cliques and has applications in link prediction, cluster detection, social network analysis and transportation ...
- ArticleSeptember 2023
- research-articleJanuary 2023
New Algorithms for Hierarchical Optimization in Kidney Exchange Programs
New Exact Approaches Tailored for Kidney Exchange Programs with Hierarchical Objectives
Kidney exchange programs increase the rate of living donor kidney transplantation. Whereas effective integer programming models aimed at maximizing the total number of ...
Many kidney exchange programs (KEPs) use integer linear programming (ILP) based on a hierarchical set of objectives to determine optimal sets of transplants. We propose innovative techniques to remove barriers in existing mathematical models, vastly ...
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- research-articleJuly 2022
Exactly characterizable parameter settings in a crossoverless evolutionary algorithm
GECCO '22: Proceedings of the Genetic and Evolutionary Computation Conference CompanionPages 1640–1649https://doi.org/10.1145/3520304.3533968The number of offspring and the population size greatly influence the performance of the Plant Propagation Algorithm, a crossover-less metaheuristic, when applied to the Euclidean traveling salesman problem. However, with large volumes of experimental ...
- research-articleJuly 2022
Exact Algorithms for Maximum Lifetime Data-Gathering Tree in Wireless Sensor Networks
INFORMS Journal on Computing (INFORMS-IJOC), Volume 34, Issue 4Pages 1987–2002https://doi.org/10.1287/ijoc.2022.1175We tackle an optimization problem arising in the design of sensor networks: given a set of sensors, only one being connected to a backbone, to establish connection routes from each of them to the sink. Under a shortest path routing protocol, the set of ...
- research-articleMay 2022
- research-articleMarch 2022
2-Opt Moves and Flips for Area-optimal Polygonizations
ACM Journal of Experimental Algorithmics (JEA), Volume 27Article No.: 2.7, Pages 1–12https://doi.org/10.1145/3500913Our work on the Computational Geometry Challenge 2019 on area-optimal polygonizations is based on two key components: (1) sampling the search space to obtain initial polygonizations and (2) optimizing such a polygonizations. Among other heuristics for ...
- research-articleMarch 2022
Area-Optimal Simple Polygonalizations: The CG Challenge 2019
ACM Journal of Experimental Algorithmics (JEA), Volume 27Article No.: 2.4, Pages 1–12https://doi.org/10.1145/3504000We give an overview of theoretical and practical aspects of finding a simple polygon of minimum (Min-Area) or maximum (Max-Area) possible area for a given set of n points in the plane. Both problems are known to be NP-hard and were the subject of the 2019 ...
- research-articleMarch 2022
Area Optimal Polygonization Using Simulated Annealing
ACM Journal of Experimental Algorithmics (JEA), Volume 27Article No.: 2.3, Pages 1–17https://doi.org/10.1145/3500911We describe a practical method to find near-optimal solutions for the area-optimal simple polygonization problem: Given a set of points S in the plane, the objective is to find a simple polygon of minimum or maximum area defined by S. Our approach is ...
- research-articleOctober 2021
Matchings under Preferences: Strength of Stability and Tradeoffs
ACM Transactions on Economics and Computation (TEAC), Volume 9, Issue 4Article No.: 20, Pages 1–55https://doi.org/10.1145/3485000We propose two solution concepts for matchings under preferences: robustness and near stability. The former strengthens while the latter relaxes the classical definition of stability by Gale and Shapley (1962). Informally speaking, robustness requires ...
- research-articleMarch 2021
Computation of Hadwiger Number and Related Contraction Problems: Tight Lower Bounds
ACM Transactions on Computation Theory (TOCT), Volume 13, Issue 2Article No.: 10, Pages 1–25https://doi.org/10.1145/3448639We prove that the Hadwiger number of an n-vertex graph G (the maximum size of a clique minor in G) cannot be computed in time no(n), unless the Exponential Time Hypothesis (ETH) fails. This resolves a well-known open question in the area of exact ...
- research-articleJuly 2020
The Vehicle Routing Problem with Partial Outsourcing
Transportation Science (TRNPS), Volume 54, Issue 4Pages 1034–1052https://doi.org/10.1287/trsc.2019.0940This paper introduces the vehicle routing problem with partial outsourcing (VRPPO) in which a customer can be served by a single private vehicle, by a common carrier, or by both a single private vehicle and a common carrier. As such, it is a variant of ...
- research-articleJune 2020
Nearly ETH-tight Algorithms for Planar Steiner Tree with Terminals on Few Faces
ACM Transactions on Algorithms (TALG), Volume 16, Issue 3Article No.: 28, Pages 1–30https://doi.org/10.1145/3371389The STEINER TREE problem is one of the most fundamental NP-complete problems, as it models many network design problems. Recall that an instance of this problem consists of a graph with edge weights and a subset of vertices (often called terminals); the ...
- research-articleJune 2019
Matchings under Preferences: Strength of Stability and Trade-Offs
EC '19: Proceedings of the 2019 ACM Conference on Economics and ComputationPages 41–59https://doi.org/10.1145/3328526.3329555We propose two solution concepts for matchings under preferences: robustness and near stability. The former strengthens while the latter relaxes the classic definition of stability by Gale and Shapley (1962). Informally speaking, robustness requires ...
- research-articleOctober 2018
Finding a Dense Subgraph with Sparse Cut
CIKM '18: Proceedings of the 27th ACM International Conference on Information and Knowledge ManagementPages 547–556https://doi.org/10.1145/3269206.3271720Community detection is one of the fundamental tasks in graph mining, which has many real-world applications in diverse domains. In this study, we propose an optimization model for finding a community that is densely connected internally but sparsely ...
- research-articleJune 2018
Stable Marriage with Multi-Modal Preferences
EC '18: Proceedings of the 2018 ACM Conference on Economics and ComputationPages 269–286https://doi.org/10.1145/3219166.3219168We thoroughly study a generalized version of the famous Stable Marriage problem, now based on multi-modal preference lists. The central twist herein is to allow each agent to rank its potentially matching counterparts based on more than one "evaluation ...
- articleMay 2017
New Algorithms for Maximum Weight Matching and a Decomposition Theorem
Mathematics of Operations Research (MOOR), Volume 42, Issue 2Pages 411–426https://doi.org/10.1287/moor.2016.0806We revisit the classical maximum weight matching problem in general graphs with nonnegative integral edge weights. We present an algorithm that operates by decomposing the problem into W unweighted versions of the problem, where W is the largest edge ...
- research-articleJuly 2016
Solving Rank-Constrained Semidefinite Programs in Exact Arithmetic
ISSAC '16: Proceedings of the 2016 ACM International Symposium on Symbolic and Algebraic ComputationPages 357–364https://doi.org/10.1145/2930889.2930925We consider the problem of minimizing a linear function over an affine section of the cone of positive semidefinite matrices, with the additional constraint that the feasible matrix has prescribed rank. When the rank constraint is active, this is a non-...