Pascal Halffmann

Dr. Pascal Halffmann

orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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10 March 2022 in Journal of Multi-Criteria Decision Analysis
Verified
Journal Article
Open access
Pascal HalffmannPascal Halffmann
Pascal Halffmann
LSLuca E. Schäfer
Luca E. Schäfer
KDKerstin Dächert
Kerstin Dächert
KKKathrin Klamroth
Kathrin Klamroth
SRStefan Ruzika
Stefan Ruzika
We provide a comprehensive overview of the literature of algorithmic approaches for multiobjective mixed‐integer and integer linear optimization problems. More precisely, we categorize and display exact methods for multiobjective linear problems with integer variables for computing the entire set of nondominated images. Our review lists 108 articles and is intended to serve as a reference for all researchers who are familiar with basic concepts of multiobjective optimization and who have an interest in getting a thorough view on the state‐of‐the‐art in multiobjective mixed‐integer programming.

23 February 2023 in Frontiers in Quantum Science and Technology
Verified
Journal Article
Open access
RARhonda Au-Yeung
Rhonda Au-Yeung
NCNicholas Chancellor
Nicholas Chancellor
Pascal HalffmannPascal Halffmann
Pascal Halffmann
In the last decade, public and industrial research funding has moved quantum computing from the early promises of Shor’s algorithm through experiments to the era of noisy intermediate scale quantum devices (NISQ) for solving real-world problems. It is likely that quantum methods can efficiently solve certain (NP-) hard optimization problems where classical approaches fail. In our perspective, we examine the field of quantum optimization, that is, solving optimization problems using quantum computers. We provide an entry point to quantum optimization for researchers from each topic, optimization or quantum computing, by demonstrating advances and obstacles with a suitable use case. We give an overview on problem formulation, available algorithms, and benchmarking. Although we show a proof-of-concept rather than a full benchmark between classical and quantum methods, this gives an idea of the current quality and capabilities of quantum computers for optimization problems. All observations are incorporated in a discussion on some recent quantum optimization breakthroughs, current status, and future directions.

30 August 2023
Verified
Book Chapter
Closed access
PDF file
Pascal HalffmannPascal Halffmann
Pascal Halffmann
PHPatrick Holzer
Patrick Holzer
KPKai Plociennik
Kai Plociennik
MTMichael Trebing
Michael Trebing

11 March 2020 in Journal of Global Optimization
Verified
Journal Article
Open access
PDF file
Pascal HalffmannPascal Halffmann
Pascal Halffmann
TDTobias Dietz
Tobias Dietz
APAnthony Przybylski
Anthony Przybylski
SRStefan Ruzika
Stefan Ruzika
This article is dedicated to the weight set decomposition of a multiobjective (mixed-)integer linear problem with three objectives. We propose an algorithm that returns a decomposition of the parameter set of the weighted sum scalarization by solving biobjective subproblems via Dichotomic Search which corresponds to a line exploration in the weight set. Additionally, we present theoretical results regarding the boundary of the weight set components that direct the line exploration. The resulting algorithm runs in output polynomial time, i.e. its running time is polynomial in the encoding length of both the input and output. Also, the proposed approach can be used for each weight set component individually and is able to give intermediate results, which can be seen as an “approximation” of the weight set component. We compare the running time of our method with the one of an existing algorithm and conduct a computational study that shows the competitiveness of our algorithm. Further, we give a state-of-the-art survey of algorithms in the literature.

2 May 2023 in Journal of Global Optimization
Verified
Journal Article
Open access
PDF file
SHStephan Helfrich
Stephan Helfrich
TPTyler Perini
Tyler Perini
Pascal HalffmannPascal Halffmann
Pascal Halffmann
NBNatashia Boland
Natashia Boland
SRStefan Ruzika
Stefan Ruzika
Scalarization is a common technique to transform a multiobjective optimization problem into a scalar-valued optimization problem. This article deals with the weighted Tchebycheff scalarization applied to multiobjective discrete optimization problems. This scalarization consists of minimizing the weighted maximum distance of the image of a feasible solution to some desirable reference point. By choosing a suitable weight, any Pareto optimal image can be obtained. In this article, we provide a comprehensive theory of this set of eligible weights. In particular, we analyze the polyhedral and combinatorial structure of the set of all weights yielding the same Pareto optimal solution as well as the decomposition of the weight set as a whole. The structural insights are linked to properties of the set of Pareto optimal solutions, thus providing a profound understanding of the weighted Tchebycheff scalarization method and, as a consequence, also of all methods for multiobjective optimization problems using this scalarization as a building block.

29 January 2024 in Risks
Verified
Journal Article
Open access
PDF file
ITIvica Turkalj
Ivica Turkalj
MAMohammad Assadsolimani
Mohammad Assadsolimani
MBMarkus Braun
Markus Braun
Pascal HalffmannPascal Halffmann
Pascal Halffmann
NHNiklas Hegemann
Niklas Hegemann
YZYuanheng Zhou
Yuanheng Zhou
In this paper, we consider the inclusion of the solvency capital requirement (SCR) into portfolio optimization by the use of a quadratic proxy model. The Solvency II directive requires insurance companies to calculate their SCR based on the complete loss distribution for the upcoming year. Since this task is, in general, computationally challenging for insurance companies (and therefore, not taken into account during portfolio optimization), employing more feasible proxy models provides a potential solution to this computational difficulty. Here, we present an approach that is also suitable for future applications in quantum computing. We analyze the approximability of the solvency capital ratio in a quadratic form using machine learning techniques. This allows for an easier consideration of the SCR in the classical mean-variance analysis. In addition, it allows the problem to be formulated as a quadratic unconstrained binary optimization (QUBO), which benefits from the potential speedup of quantum computing. We provide a detailed description of our model and the translation into a QUBO. Furthermore, we investigate the performance of our approach through experimental studies.