Jakob Bossek

Jakob Bossek
RWTH Aachen University · Department of Computer Science

Dr. rer. pol.

About

85
Publications
6,457
Reads
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651
Citations
Additional affiliations
April 2022 - present
RWTH Aachen University
Position
  • PostDoc Position
October 2019 - September 2020
University of Adelaide
Position
  • PostDoc Position
December 2018 - March 2022
University of Münster
Position
  • PostDoc Position
Education
October 2008 - July 2013
Technische Universität Dortmund
Field of study
  • Statistics
October 2006 - December 2014
Technische Universität Dortmund
Field of study
  • Computer Science

Publications

Publications (85)
Preprint
Recently different evolutionary computation approaches have been developed that generate sets of high quality diverse solutions for a given optimisation problem. Many studies have considered diversity 1) as a mean to explore niches in behavioural space (quality diversity) or 2) to increase the structural differences of solutions (evolutionary diver...
Preprint
Generating instances of different properties is key to algorithm selection methods that differentiate between the performance of different solvers for a given combinatorial optimization problem. A wide range of methods using evolutionary computation techniques has been introduced in recent years. With this paper, we contribute to this area of resea...
Chapter
Full-text available
Computing sets of high quality solutions has gained increasing interest in recent years. In this paper, we investigate how to obtain sets of optimal solutions for the classical knapsack problem. We present an algorithm to count exactly the number of optima to a zero-one knapsack problem instance. In addition, we show how to efficiently sample unifo...
Article
Full-text available
We contribute to the theoretical understanding of randomized search heuristics for dynamic problems. We consider the classical vertex coloring problem on graphs and investigate the dynamic setting where edges are added to the current graph. We then analyze the expected time for randomized search heuristics to recompute high quality solutions. The (...
Preprint
Evolutionary algorithms based on edge assembly crossover~(EAX) constitute some of the best performing incomplete solvers for the well-known traveling salesperson problem~(TSP). Often, it is desirable to compute not just a single solution for a given problem, but a diverse set of high quality solutions from which a decision maker can choose one for...
Preprint
Full-text available
Computing sets of high quality solutions has gained increasing interest in recent years. In this paper, we investigate how to obtain sets of optimal solutions for the classical knapsack problem. We present an algorithm to count exactly the number of optima to a zero-one knapsack problem instance. In addition, we show how to efficiently sample unifo...
Preprint
We contribute to the theoretical understanding of randomized search heuristics for dynamic problems. We consider the classical vertex coloring problem on graphs and investigate the dynamic setting where edges are added to the current graph. We then analyze the expected time for randomized search heuristics to recompute high quality solutions. The (...
Preprint
Full-text available
In recent years, Evolutionary Algorithms (EAs) have frequently been adopted to evolve instances for optimization problems that pose difficulties for one algorithm while being rather easy for a competitor and vice versa. Typically, this is achieved by either minimizing or maximizing the performance difference or ratio which serves as the fitness fun...
Preprint
In practise, it is often desirable to provide the decision-maker with a rich set of diverse solutions of decent quality instead of just a single solution. In this paper we study evolutionary diversity optimization for the knapsack problem (KP). Our goal is to evolve a population of solutions that all have a profit of at least $(1-\varepsilon)\cdot...
Preprint
Full-text available
Computing diverse sets of high-quality solutions has gained increasing attention among the evolutionary computation community in recent years. It allows practitioners to choose from a set of high-quality alternatives. In this paper, we employ a population diversity measure, called the high-order entropy measure, in an evolutionary algorithm to comp...
Preprint
Full-text available
Submodular functions allow to model many real-world optimisation problems. This paper introduces approaches for computing diverse sets of high quality solutions for submodular optimisation problems. We first present diversifying greedy sampling approaches and analyse them with respect to the diversity measured by entropy and the approximation quali...
Preprint
Full-text available
In the area of evolutionary computation the calculation of diverse sets of high-quality solutions to a given optimization problem has gained momentum in recent years under the term evolutionary diversity optimization. Theoretical insights into the working principles of baseline evolutionary algorithms for diversity optimization are still rare. In t...
Chapter
One-shot optimization tasks require to determine the set of solution candidates prior to their evaluation, i.e., without possibility for adaptive sampling. We consider two variants, classic one-shot optimization (where our aim is to find at least one solution of high quality) and one-shot regression (where the goal is to fit a model that resembles...
Chapter
The Traveling Salesperson Problem (TSP) is one of the best-known combinatorial optimisation problems. However, many real-world problems are composed of several interacting components. The Traveling Thief Problem (TTP) addresses such interactions by combining two combinatorial optimisation problems, namely the TSP and the Knapsack Problem (KP). Rece...
Chapter
In this work we focus on the well-known Euclidean Traveling Salesperson Problem (TSP) and two highly competitive inexact heuristic TSP solvers, EAX and LKH, in the context of per-instance algorithm selection (AS). We evolve instances with nodes where the solvers show strongly different performance profiles. These instances serve as a basis for an e...
Preprint
Full-text available
This survey compiles ideas and recommendations from more than a dozen researchers with different backgrounds and from different institutes around the world. Promoting best practice in benchmarking is its main goal. The article discusses eight essential topics in benchmarking: clearly stated goals, well-specified problems, suitable algorithms, adequ...
Preprint
In this work we focus on the well-known Euclidean Traveling Salesperson Problem (TSP) and two highly competitive inexact heuristic TSP solvers, EAX and LKH, in the context of per-instance algorithm selection (AS). We evolve instances with 1,000 nodes where the solvers show strongly different performance profiles. These instances serve as a basis fo...
Preprint
The Traveling Salesperson Problem (TSP) is one of the best-known combinatorial optimisation problems. However, many real-world problems are composed of several interacting components. The Traveling Thief Problem (TTP) addresses such interactions by combining two combinatorial optimisation problems, namely the TSP and the Knapsack Problem (KP). Rece...
Preprint
Dynamic optimization problems have gained significant attention in evolutionary computation as evolutionary algorithms (EAs) can easily adapt to changing environments. We show that EAs can solve the graph coloring problem for bipartite graphs more efficiently by using dynamic optimization. In our approach the graph instance is given incrementally s...
Preprint
Full-text available
We consider a dynamic bi-objective vehicle routing problem, where a subset of customers ask for service over time. Therein, the distance traveled by a single vehicle and the number of unserved dynamic requests is minimized by a dynamic evolutionary multi-objective algorithm (DEMOA), which operates on discrete time windows (eras). A decision is made...
Preprint
Full-text available
In practice, e.g. in delivery and service scenarios, Vehicle-Routing-Problems (VRPs) often imply repeated decision making on dynamic customer requests. As in classical VRPs, tours have to be planned short while the number of serviced customers has to be maximized at the same time resulting in a multi-objective problem. Beyond that, however, dynamic...
Preprint
The Traveling-Salesperson-Problem (TSP) is arguably one of the best-known NP-hard combinatorial optimization problems. The two sophisticated heuristic solvers LKH and EAX and respective (restart) variants manage to calculate close-to optimal or even optimal solutions, also for large instances with several thousand nodes in reasonable time. In this...
Preprint
Evolutionary algorithms (EAs) are general-purpose problem solvers that usually perform an unbiased search. This is reasonable and desirable in a black-box scenario. For combinatorial optimization problems, often more knowledge about the structure of optimal solutions is given, which can be leveraged by means of biased search operators. We consider...
Preprint
Full-text available
Evolving diverse sets of high quality solutions has gained increasing interest in the evolutionary computation literature in recent years. With this paper, we contribute to this area of research by examining evolutionary diversity optimisation approaches for the classical Traveling Salesperson Problem (TSP). We study the impact of using different d...
Preprint
Full-text available
Sequential model-based optimization (SMBO) approaches are algorithms for solving problems that require computationally or otherwise expensive function evaluations. The key design principle of SMBO is a substitution of the true objective function by a surrogate, which is used to propose the point(s) to be evaluated next. SMBO algorithms are intrinsi...
Preprint
Several important optimization problems in the area of vehicle routing can be seen as a variant of the classical Traveling Salesperson Problem (TSP). In the area of evolutionary computation, the traveling thief problem (TTP) has gained increasing interest over the last 5 years. In this paper, we investigate the effect of weights on such problems, i...
Preprint
One-shot decision making is required in situations in which we can evaluate a fixed number of solution candidates but do not have any possibility for further, adaptive sampling. Such settings are frequently encountered in neural network design, hyper-parameter optimization, and many simulation-based real-world optimization tasks, in which evaluatio...
Article
We build upon a recently proposed multi-objective view onto performance measurement of single-objective stochastic solvers. The trade-off between the fraction of failed runs and the mean runtime of successful runs – both to be minimized – is directly analyzed based on a study on algorithm selection of inexact state-of-the-art solvers for the famous...
Article
Full-text available
OpenML is an online machine learning platform where researchers can easily share data, machine learning tasks and experiments as well as organize them online to work and collaborate more efficiently. In this paper, we present an R package to interface with the OpenML platform and illustrate its usage in combination with the machine learning R packa...
Conference Paper
The edge coloring problem asks for an assignment of colors to edges of a graph such that no two incident edges share the same color and the number of colors is minimized. It is known that all graphs with maximum degree Δ can be colored with Δ or Δ + 1 colors, but it is NP-hard to determine whether Δ colors are sufficient. We present the first runti...
Conference Paper
Evolutionary algorithms have successfully been applied to evolve problem instances that exhibit a significant difference in performance for a given algorithm or a pair of algorithms inter alia for the Traveling Salesperson Problem (TSP). Creating a large variety of instances is crucial for successful applications in the blooming field of algorithm...
Conference Paper
Research has shown that for many single-objective graph problems where optimum solutions are composed of low weight sub-graphs, such as the minimum spanning tree problem (MST), mutation operators favoring low weight edges show superior performance. Intuitively, similar observations should hold for multi-criteria variants of such problems. In this w...
Conference Paper
We contribute to the theoretical understanding of randomized search heuristics for dynamic problems. We consider the classical graph coloring problem and investigate the dynamic setting where edges are added to the current graph. We then analyze the expected time for randomized search heuristics to recompute high quality solutions. This includes th...
Chapter
A multiobjective perspective onto common performance measures such as the PAR10 score or the expected runtime of single-objective stochastic solvers is presented by directly investigating the tradeoff between the fraction of failed runs and the average runtime. Multi-objective indicators operating in the bi-objective space allow for an overall perf...
Chapter
The \(\mathcal {NP}\)-hard multi-criteria shortest path problem (mcSPP) is of utmost practical relevance, e. g., in navigation system design and logistics. We address the problem of approximating the Pareto-front of the mcSPP with sum objectives. We do so by proposing a new mutation operator for multi-objective evolutionary algorithms that solves s...
Chapter
Dieses Kapitel bietet eine Einführung in die Optimierung linearer Zielfunktionen unter Nebenbedingungen. Aufbauend auf einer fundierten Einführung in Notation und grafische Interpretierbarkeit linearer Probleme wird mit der Simplex-Methode nach Dantzig ein effizientes und im Bereich Operations Research zentrales Verfahren zu deren Lösung vorgestell...
Chapter
Das Kapitel verschafft zuerst einen nicht formalen Einstieg in die Begrifflichkeit der Optimierung und geht dann zur formalen Definition von Optimierungsproblemen über. Die Abstraktion durch Formalität verdeutlicht es an einigen beispielhaften Problemstellungen. Dabei spielen insbesondere auch Themen wie Modellbildung/Abstraktion, Lösungsmethodik u...
Chapter
Dieses Kapitel widmet sich nichtlinearen Problemstellungen, also jenen Optimierungsproblemen, die entweder in der Problemformulierung selbst oder den Randbedingungen nicht linear sind. Auf eine kurze Rekapitulation von Basiswissen aus der Analysis (Differenziation, Lagrange-Methode) folgt die Vorstellung diverser deterministischer, numerischer Lösu...
Chapter
Als Abschluss des Buches soll das Kapitel zur Entscheidungstheorie einen anderen, allgemeineren Blickwinkel auf die Problematik der Optimierung vermitteln. Nach einer sehr grundlegenden Einführung in die (traditionelle) Theorie der Entscheidungsfindung sollen die Zusammenhänge zwischen Entscheidungstheorie und Optimierung herausgearbeitet werden. H...
Chapter
Thema dieses Kapitels sind von der Natur inspirierte algorithmische Konzepte und Verfahren. Aufbauend auf den Ideen der modernen Evolutionstheorie (nach Darwin) und der systematischen Einbindung von Zufall wird in das Gebiet der evolutionären Algorithmen eingeführt. Für diese inzwischen weit verbreiteten und akzeptierten Verfahren wird eine praxiso...
Chapter
Das Kapitel betrachtet Graphen und Bäume (als spezielle Klasse) zweigeteilt: einerseits als Datenstruktur zur Modellierung von Optimierungsproblemen, auf die ein Optimierungsverfahren angewandt wird (kürzeste Wege, Flussprobleme), andererseits als strukturgebende Elemente für die Konstruktion von Optimierungsverfahren selbst (Strukturierung des Suc...
Conference Paper
Assessing the performance of stochastic optimization algorithms in the field of multi-objective optimization is of utmost importance. Besides the visual comparison of the obtained approximation sets, more sophisticated methods have been proposed in the last decade, e. g., a variety of quantitative performance indicators or statistical tests. In thi...
Conference Paper
Performance comparisons of optimization algorithms are heavily influenced by the underlying indicator(s). In this paper we investigate commonly used performance indicators for single-objective stochastic solvers, such as the Penalized Average Runtime (e.g., PAR10) or the Expected Running Time (ERT), based on exemplary benchmark performances of stat...
Conference Paper
We analyze the effects of including local search techniques into a multi-objective evolutionary algorithm for solving a bi-objective orienteering problem with a single vehicle while the two conflicting objectives are minimization of travel time and maximization of the number of visited customer locations. Experiments are based on a large set of spe...
Book
Dieses Lehrbuch vermittelt einen breiten und grundlegenden Einblick in das methodische Verständnis für die Problematik der Optimierung. Im Fokus stehen Algorithmen und Komplexität verschiedener Optimierungsprobleme sowie nützliche Lösungsmethoden und Anwendungsbezug. Dabei wird auf eine ausführliche Darstellung der wichtigen Konzepte der Optimierun...
Article
The Travelling Salesperson Problem (TSP) is one of the best-studied NP-hard problems. Over the years, many different solution approaches and solvers have been developed. For the first time, we directly compare five state-of-the-art inexact solvers - namely, LKH, EAX, restart variants of those, and MAOS - on a large set of well-known benchmark insta...
Conference Paper
The novel R package ecr (version 2), short for Evolutionary Computation in R, provides a comprehensive collection of building blocks for constructing powerful evolutionary algorithms for single- and multi-objective continuous and combinatorial optimization problems. It allows to solve standard optimization tasks with few lines of code using a black...
Article
Full-text available
Benchmarking algorithms for optimization problems usually is carried out by running the algorithms under consideration on a diverse set of benchmark or test functions. A vast variety of test functions was proposed by researchers and is being used for investigations in the literature. The smoof package implements a large set of test functions and te...
Article
Full-text available
We present mlrMBO, a flexible and comprehensive R toolbox for model-based optimization (MBO), also known as Bayesian optimization, which addresses the problem of expensive black-box optimization by approximating the given objective function through a surrogate regression model. It is designed for both single- and multi-objective optimization with m...
Conference Paper
State of the Art inexact solvers of the NP-hard Traveling Salesperson Problem (TSP) are known to mostly yield high-quality solutions in reasonable computation times. With the purpose of understanding different levels of instance difficulties, instances for the current State of the Art heuristic TSP solvers LKH+restart and EAX+restart are presented...
Code
’OpenML.org’ is an online machine learning platform where researchers can automatically share data, machine learning tasks and experiments and organize them online to work and collaborate more effectively. We provide a R interface to the OpenML REST API in order to download and upload data sets, tasks, flows and runs, see <http://www.openml.org/gui...
Presentation
Full-text available
Many practical optimization tasks, such as finding best parameters for simulators in engineering or hyperparameter optimization in machine learning, are of a black-box nature, i.e., neither formulas of the objective nor derivative information is available. Instead, we can only query the box for its objective value at a given point. If such a query...
Presentation
Full-text available
OpenML is an online machine learning platform where researchers can automatically log and share data, code, and experiments, and organize them online to work and collaborate more effectively. We present an R package to interface the OpenML platform and illustrate its usage both as a stand-alone package and in combination with the mlr machine learni...
Conference Paper
Despite the intrinsic hardness of the Traveling Salesperson Problem (TSP) heuristic solvers, e.g., LKH+restart and EAX+restart, are remarkably successful in generating satisfactory or even optimal solutions. However, the reasons for their success are not yet fully understood. Recent approaches take an analytical viewpoint and try to identify instan...
Conference Paper
Full-text available
The majority of algorithms can be controlled or adjusted by parameters. Their values can substantially affect the algorithms' performance. Since the manual exploration of the parameter space is tedious -- even for few parameters -- several automatic procedures for parameter tuning have been proposed. Recent approaches also take into account some ch...
Conference Paper
Full-text available
We evaluate the performance of a multi-objective evolutionary algorithm on a class of dynamic routing problems with a single vehicle. In particular we focus on relating algo-rithmic performance to the most prominent characteristics of problem instances. The routing problem considers two types of customers: mandatory customers must be visited wherea...
Conference Paper
With this paper we contribute to the understanding of the success of 2-opt based local search algorithms for solving the traveling salesman problem (TSP). Although 2-opt is widely used in practice, it is hard to understand its success from a theoretical perspective. We take a statistical approach and examine the features of TSP instances that make...

Projects

Projects (4)
Project
Provides generators for a high number of both single- and multi-objective test functions which are frequently used for the benchmarking of (numerical) optimization algorithms. Moreover, it offers a set of convenient functions to generate, plot and work with objective functions.
Project
This R package provides a powerful framework for evolutionary computing in R. The user can easily construct powerful evolutionary algorithms for tackling both single- and multi-objective problems by plugging in different predefined evolutionary building blocks, e. g., operators for mutation, recombination and selection with just a few lines of code. Extending the framework with own operators and representations is also possible. Additionally there are various comfort functions, like monitoring, logging and more.
Project
With mlr we offer a package that makes many machine learning tasks super easy in R, such as bench marking of different methods, hyper-parameter optimization (tuning) and many more. With mlr it is not necessary to write cumbersome custom code anymore.