---
_id: '46469'
abstract:
- lang: eng
  text: 'We show how to learn discrete field theories from observational data of fields
    on a space-time lattice. For this, we train a neural network model of a discrete
    Lagrangian density such that the discrete Euler--Lagrange equations are consistent
    with the given training data. We, thus, obtain a structure-preserving machine
    learning architecture. Lagrangian densities are not uniquely defined by the solutions
    of a field theory. We introduce a technique to derive regularisers for the training
    process which optimise numerical regularity of the discrete field theory. Minimisation
    of the regularisers guarantees that close to the training data the discrete field
    theory behaves robust and efficient when used in numerical simulations. Further,
    we show how to identify structurally simple solutions of the underlying continuous
    field theory such as travelling waves. This is possible even when travelling waves
    are not present in the training data. This is compared to data-driven model order
    reduction based approaches, which struggle to identify suitable latent spaces
    containing structurally simple solutions when these are not present in the training
    data. Ideas are demonstrated on examples based on the wave equation and the Schrödinger
    equation. '
article_number: '013104'
article_type: original
author:
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
citation:
  ama: Offen C, Ober-Blöbaum S. Learning of discrete models of variational PDEs from
    data. <i>Chaos</i>. 2024;34(1). doi:<a href="https://doi.org/10.1063/5.0172287">10.1063/5.0172287</a>
  apa: Offen, C., &#38; Ober-Blöbaum, S. (2024). Learning of discrete models of variational
    PDEs from data. <i>Chaos</i>, <i>34</i>(1), Article 013104. <a href="https://doi.org/10.1063/5.0172287">https://doi.org/10.1063/5.0172287</a>
  bibtex: '@article{Offen_Ober-Blöbaum_2024, title={Learning of discrete models of
    variational PDEs from data}, volume={34}, DOI={<a href="https://doi.org/10.1063/5.0172287">10.1063/5.0172287</a>},
    number={1013104}, journal={Chaos}, publisher={AIP Publishing}, author={Offen,
    Christian and Ober-Blöbaum, Sina}, year={2024} }'
  chicago: Offen, Christian, and Sina Ober-Blöbaum. “Learning of Discrete Models of
    Variational PDEs from Data.” <i>Chaos</i> 34, no. 1 (2024). <a href="https://doi.org/10.1063/5.0172287">https://doi.org/10.1063/5.0172287</a>.
  ieee: 'C. Offen and S. Ober-Blöbaum, “Learning of discrete models of variational
    PDEs from data,” <i>Chaos</i>, vol. 34, no. 1, Art. no. 013104, 2024, doi: <a
    href="https://doi.org/10.1063/5.0172287">10.1063/5.0172287</a>.'
  mla: Offen, Christian, and Sina Ober-Blöbaum. “Learning of Discrete Models of Variational
    PDEs from Data.” <i>Chaos</i>, vol. 34, no. 1, 013104, AIP Publishing, 2024, doi:<a
    href="https://doi.org/10.1063/5.0172287">10.1063/5.0172287</a>.
  short: C. Offen, S. Ober-Blöbaum, Chaos 34 (2024).
date_created: 2023-08-10T08:24:48Z
date_updated: 2024-08-12T13:45:43Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.1063/5.0172287
external_id:
  arxiv:
  - '2308.05082 '
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2024-01-09T10:48:38Z
  date_updated: 2024-01-09T10:48:38Z
  file_id: '50376'
  file_name: Accepted manuscript with AIP banner CHA23-AR-01370.pdf
  file_size: 13222105
  relation: main_file
  title: Accepted Manuscript Chaos
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2024-01-09T11:19:49Z
  date_updated: 2024-01-09T11:19:49Z
  description: |-
    We show how to learn discrete field theories from observational data of fields on a space-time lattice. For this, we train
    a neural network model of a discrete Lagrangian density such that the discrete Euler–Lagrange equations are consistent
    with the given training data. We, thus, obtain a structure-preserving machine learning architecture. Lagrangian
    densities are not uniquely defined by the solutions of a field theory. We introduce a technique to derive regularisers for
    the training process which optimise numerical regularity of the discrete field theory. Minimisation of the regularisers
    guarantees that close to the training data the discrete field theory behaves robust and efficient when used in numerical
    simulations. Further, we show how to identify structurally simple solutions of the underlying continuous field theory
    such as travelling waves. This is possible even when travelling waves are not present in the training data. This is
    compared to data-driven model order reduction based approaches, which struggle to identify suitable latent spaces
    containing structurally simple solutions when these are not present in the training data. Ideas are demonstrated on
    examples based on the wave equation and the Schrödinger equation.
  file_id: '50390'
  file_name: LDensityPDE_AIP.pdf
  file_size: 12960884
  relation: main_file
  title: Learning of discrete models of variational PDEs from data
file_date_updated: 2024-01-09T11:19:49Z
has_accepted_license: '1'
intvolume: '        34'
issue: '1'
language:
- iso: eng
oa: '1'
project:
- _id: '52'
  name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication: Chaos
publication_identifier:
  issn:
  - 1054-1500
publication_status: published
publisher: AIP Publishing
quality_controlled: '1'
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/Christian-Offen/DLNN_pde
status: public
title: Learning of discrete models of variational PDEs from data
type: journal_article
user_id: '85279'
volume: 34
year: '2024'
...
---
_id: '55159'
abstract:
- lang: eng
  text: "We introduce a method based on Gaussian process regression to identify discrete
    variational principles from observed solutions of a field theory. The method is
    based on the data-based identification of a discrete Lagrangian density. It is
    a geometric machine learning technique in the sense that the variational structure
    of the true field theory is reflected in the data-driven model by design. We provide
    a rigorous convergence statement of the method. The proof circumvents challenges
    posed by the ambiguity of discrete Lagrangian densities in the inverse problem
    of variational calculus.\r\nMoreover, our method can be used to quantify model
    uncertainty in the equations of motions and any linear observable of the discrete
    field theory. This is illustrated on the example of the discrete wave equation
    and Schrödinger equation.\r\nThe article constitutes an extension of our previous
    article  arXiv:2404.19626 for the data-driven identification of (discrete) Lagrangians
    for variational dynamics from an ode setting to the setting of discrete pdes."
author:
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
citation:
  ama: Offen C. Machine learning of discrete field theories with guaranteed convergence
    and uncertainty quantification.
  apa: Offen, C. (n.d.). <i>Machine learning of discrete field theories with guaranteed
    convergence and uncertainty quantification</i>.
  bibtex: '@article{Offen, title={Machine learning of discrete field theories with
    guaranteed convergence and uncertainty quantification}, author={Offen, Christian}
    }'
  chicago: Offen, Christian. “Machine Learning of Discrete Field Theories with Guaranteed
    Convergence and Uncertainty Quantification,” n.d.
  ieee: C. Offen, “Machine learning of discrete field theories with guaranteed convergence
    and uncertainty quantification.” .
  mla: Offen, Christian. <i>Machine Learning of Discrete Field Theories with Guaranteed
    Convergence and Uncertainty Quantification</i>.
  short: C. Offen, (n.d.).
date_created: 2024-07-10T13:43:50Z
date_updated: 2024-08-12T13:43:32Z
ddc:
- '510'
department:
- _id: '636'
external_id:
  arxiv:
  - '2407.07642'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2024-07-10T13:39:32Z
  date_updated: 2024-07-10T13:39:32Z
  description: |-
    We introduce a method based on Gaussian process regression to identify discrete
    variational principles from observed solutions of a field theory. The method is based on the data-based identification of a discrete Lagrangian density. It is a geometric machine learning technique in the sense that the variational structure of the true field theory is reflected in the data-driven model by design.
    We provide a rigorous convergence statement of the method.
    The proof circumvents challenges posed by the ambiguity of discrete Lagrangian densities in the inverse problem of variational calculus.
    Moreover, our method can be used to quantify model uncertainty in the equations of motions and any linear observable of the discrete field theory.
    This is illustrated on the example of the discrete wave equation and Schrödinger equation.
    The article constitutes an extension of our previous article for the data-driven identification of (discrete) Lagrangians for variational dynamics from an ode setting to the setting of discrete pdes.
  file_id: '55160'
  file_name: L_Collocation.pdf
  file_size: 4569314
  relation: main_file
  title: Machine learning of discrete field theories with guaranteed convergence and
    uncertainty quantification
file_date_updated: 2024-07-10T13:39:32Z
has_accepted_license: '1'
keyword:
- System identification
- inverse problem of variational calculus
- Gaussian process
- Lagrangian learning
- physics informed machine learning
- geometry aware learning
language:
- iso: eng
oa: '1'
page: '28'
project:
- _id: '52'
  name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication_status: submitted
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/Christian-Offen/Lagrangian_GP_PDE
status: public
title: Machine learning of discrete field theories with guaranteed convergence and
  uncertainty quantification
type: preprint
user_id: '85279'
year: '2024'
...
---
_id: '59791'
author:
- first_name: Sofya
  full_name: Maslovskaya, Sofya
  id: '87909'
  last_name: Maslovskaya
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
citation:
  ama: 'Maslovskaya S, Ober-Blöbaum S. Symplectic Methods in Deep Learning. In: <i>IFAC-PapersOnLine</i>.
    Vol 58. Elsevier BV; 2024:85-90. doi:<a href="https://doi.org/10.1016/j.ifacol.2024.10.118">10.1016/j.ifacol.2024.10.118</a>'
  apa: Maslovskaya, S., &#38; Ober-Blöbaum, S. (2024). Symplectic Methods in Deep
    Learning. <i>IFAC-PapersOnLine</i>, <i>58</i>(17), 85–90. <a href="https://doi.org/10.1016/j.ifacol.2024.10.118">https://doi.org/10.1016/j.ifacol.2024.10.118</a>
  bibtex: '@inproceedings{Maslovskaya_Ober-Blöbaum_2024, title={Symplectic Methods
    in Deep Learning}, volume={58}, DOI={<a href="https://doi.org/10.1016/j.ifacol.2024.10.118">10.1016/j.ifacol.2024.10.118</a>},
    number={17}, booktitle={IFAC-PapersOnLine}, publisher={Elsevier BV}, author={Maslovskaya,
    Sofya and Ober-Blöbaum, Sina}, year={2024}, pages={85–90} }'
  chicago: Maslovskaya, Sofya, and Sina Ober-Blöbaum. “Symplectic Methods in Deep
    Learning.” In <i>IFAC-PapersOnLine</i>, 58:85–90. Elsevier BV, 2024. <a href="https://doi.org/10.1016/j.ifacol.2024.10.118">https://doi.org/10.1016/j.ifacol.2024.10.118</a>.
  ieee: 'S. Maslovskaya and S. Ober-Blöbaum, “Symplectic Methods in Deep Learning,”
    in <i>IFAC-PapersOnLine</i>, 2024, vol. 58, no. 17, pp. 85–90, doi: <a href="https://doi.org/10.1016/j.ifacol.2024.10.118">10.1016/j.ifacol.2024.10.118</a>.'
  mla: Maslovskaya, Sofya, and Sina Ober-Blöbaum. “Symplectic Methods in Deep Learning.”
    <i>IFAC-PapersOnLine</i>, vol. 58, no. 17, Elsevier BV, 2024, pp. 85–90, doi:<a
    href="https://doi.org/10.1016/j.ifacol.2024.10.118">10.1016/j.ifacol.2024.10.118</a>.
  short: 'S. Maslovskaya, S. Ober-Blöbaum, in: IFAC-PapersOnLine, Elsevier BV, 2024,
    pp. 85–90.'
date_created: 2025-05-05T09:21:13Z
date_updated: 2025-05-05T09:22:27Z
department:
- _id: '636'
doi: 10.1016/j.ifacol.2024.10.118
intvolume: '        58'
issue: '17'
language:
- iso: eng
page: 85-90
publication: IFAC-PapersOnLine
publication_identifier:
  issn:
  - 2405-8963
publication_status: published
publisher: Elsevier BV
status: public
title: Symplectic Methods in Deep Learning
type: conference
user_id: '87909'
volume: 58
year: '2024'
...
---
_id: '59801'
author:
- first_name: Frédéric
  full_name: Jean, Frédéric
  last_name: Jean
- first_name: Sofya
  full_name: Maslovskaya, Sofya
  id: '87909'
  last_name: Maslovskaya
citation:
  ama: Jean F, Maslovskaya S. Inverse optimal control problem in the non autonomous
    linear-quadratic case. Published online 2024.
  apa: Jean, F., &#38; Maslovskaya, S. (2024). <i>Inverse optimal control problem
    in the non autonomous linear-quadratic case</i>.
  bibtex: '@article{Jean_Maslovskaya_2024, title={Inverse optimal control problem
    in the non autonomous linear-quadratic case}, author={Jean, Frédéric and Maslovskaya,
    Sofya}, year={2024} }'
  chicago: Jean, Frédéric, and Sofya Maslovskaya. “Inverse Optimal Control Problem
    in the Non Autonomous Linear-Quadratic Case,” 2024.
  ieee: F. Jean and S. Maslovskaya, “Inverse optimal control problem in the non autonomous
    linear-quadratic case.” 2024.
  mla: Jean, Frédéric, and Sofya Maslovskaya. <i>Inverse Optimal Control Problem in
    the Non Autonomous Linear-Quadratic Case</i>. 2024.
  short: F. Jean, S. Maslovskaya, (2024).
date_created: 2025-05-05T09:42:19Z
date_updated: 2025-05-05T09:43:05Z
department:
- _id: '636'
language:
- iso: eng
status: public
title: Inverse optimal control problem in the non autonomous linear-quadratic case
type: preprint
user_id: '87909'
year: '2024'
...
---
_id: '34135'
abstract:
- lang: eng
  text: By one of the most fundamental principles in physics, a dynamical system will
    exhibit those motions which extremise an action functional. This leads to the
    formation of the Euler-Lagrange equations, which serve as a model of how the system
    will behave in time. If the dynamics exhibit additional symmetries, then the motion
    fulfils additional conservation laws, such as conservation of energy (time invariance),
    momentum (translation invariance), or angular momentum (rotational invariance).
    To learn a system representation, one could learn the discrete Euler-Lagrange
    equations, or alternatively, learn the discrete Lagrangian function Ld which defines
    them. Based on ideas from Lie group theory, in this work we introduce a framework
    to learn a discrete Lagrangian along with its symmetry group from discrete observations
    of motions and, therefore, identify conserved quantities. The learning process
    does not restrict the form of the Lagrangian, does not require velocity or momentum
    observations or predictions and incorporates a cost term which safeguards against
    unwanted solutions and against potential numerical issues in forward simulations.
    The learnt discrete quantities are related to their continuous analogues using
    variational backward error analysis and numerical results demonstrate the improvement
    such models can have both qualitatively and quantitatively even in the presence
    of noise.
author:
- first_name: Yana
  full_name: Lishkova, Yana
  last_name: Lishkova
- first_name: Paul
  full_name: Scherer, Paul
  last_name: Scherer
- first_name: Steffen
  full_name: Ridderbusch, Steffen
  last_name: Ridderbusch
- first_name: Mateja
  full_name: Jamnik, Mateja
  last_name: Jamnik
- first_name: Pietro
  full_name: Liò, Pietro
  last_name: Liò
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
citation:
  ama: 'Lishkova Y, Scherer P, Ridderbusch S, et al. Discrete Lagrangian Neural Networks
    with Automatic Symmetry Discovery. In: <i>IFAC-PapersOnLine</i>. Vol 56. Elsevier;
    2023:3203-3210. doi:<a href="https://doi.org/10.1016/j.ifacol.2023.10.1457">10.1016/j.ifacol.2023.10.1457</a>'
  apa: Lishkova, Y., Scherer, P., Ridderbusch, S., Jamnik, M., Liò, P., Ober-Blöbaum,
    S., &#38; Offen, C. (2023). Discrete Lagrangian Neural Networks with Automatic
    Symmetry Discovery. <i>IFAC-PapersOnLine</i>, <i>56</i>(2), 3203–3210. <a href="https://doi.org/10.1016/j.ifacol.2023.10.1457">https://doi.org/10.1016/j.ifacol.2023.10.1457</a>
  bibtex: '@inproceedings{Lishkova_Scherer_Ridderbusch_Jamnik_Liò_Ober-Blöbaum_Offen_2023,
    title={Discrete Lagrangian Neural Networks with Automatic Symmetry Discovery},
    volume={56}, DOI={<a href="https://doi.org/10.1016/j.ifacol.2023.10.1457">10.1016/j.ifacol.2023.10.1457</a>},
    number={2}, booktitle={IFAC-PapersOnLine}, publisher={Elsevier}, author={Lishkova,
    Yana and Scherer, Paul and Ridderbusch, Steffen and Jamnik, Mateja and Liò, Pietro
    and Ober-Blöbaum, Sina and Offen, Christian}, year={2023}, pages={3203–3210} }'
  chicago: Lishkova, Yana, Paul Scherer, Steffen Ridderbusch, Mateja Jamnik, Pietro
    Liò, Sina Ober-Blöbaum, and Christian Offen. “Discrete Lagrangian Neural Networks
    with Automatic Symmetry Discovery.” In <i>IFAC-PapersOnLine</i>, 56:3203–10. Elsevier,
    2023. <a href="https://doi.org/10.1016/j.ifacol.2023.10.1457">https://doi.org/10.1016/j.ifacol.2023.10.1457</a>.
  ieee: 'Y. Lishkova <i>et al.</i>, “Discrete Lagrangian Neural Networks with Automatic
    Symmetry Discovery,” in <i>IFAC-PapersOnLine</i>,  Yokohama, Japan, 2023, vol.
    56, no. 2, pp. 3203–3210, doi: <a href="https://doi.org/10.1016/j.ifacol.2023.10.1457">10.1016/j.ifacol.2023.10.1457</a>.'
  mla: Lishkova, Yana, et al. “Discrete Lagrangian Neural Networks with Automatic
    Symmetry Discovery.” <i>IFAC-PapersOnLine</i>, vol. 56, no. 2, Elsevier, 2023,
    pp. 3203–10, doi:<a href="https://doi.org/10.1016/j.ifacol.2023.10.1457">10.1016/j.ifacol.2023.10.1457</a>.
  short: 'Y. Lishkova, P. Scherer, S. Ridderbusch, M. Jamnik, P. Liò, S. Ober-Blöbaum,
    C. Offen, in: IFAC-PapersOnLine, Elsevier, 2023, pp. 3203–3210.'
conference:
  end_date: 2023-07-14
  location: ' Yokohama, Japan'
  name: The 22nd World Congress of the International Federation of Automatic Control
  start_date: 2023-07-09
date_created: 2022-11-23T08:17:10Z
date_updated: 2023-12-29T14:26:00Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.1016/j.ifacol.2023.10.1457
external_id:
  arxiv:
  - '2211.10830'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2023-04-17T08:05:55Z
  date_updated: 2023-04-17T08:05:55Z
  description: |-
    By one of the most fundamental principles in physics, a dynamical system will
    exhibit those motions which extremise an action functional. This leads to the formation of
    the Euler-Lagrange equations, which serve as a model of how the system will behave in time.
    If the dynamics exhibit additional symmetries, then the motion fulfils additional conservation
    laws, such as conservation of energy (time invariance), momentum (translation invariance), or
    angular momentum (rotational invariance). To learn a system representation, one could learn
    the discrete Euler-Lagrange equations, or alternatively, learn the discrete Lagrangian function
    Ld which defines them. Based on ideas from Lie group theory, we introduce a framework to learn
    a discrete Lagrangian along with its symmetry group from discrete observations of motions and,
    therefore, identify conserved quantities. The learning process does not restrict the form of the
    Lagrangian, does not require velocity or momentum observations or predictions and incorporates
    a cost term which safeguards against unwanted solutions and against potential numerical issues
    in forward simulations. The learnt discrete quantities are related to their continuous analogues
    using variational backward error analysis and numerical results demonstrate the improvement
    such models can have both qualitatively and quantitatively even in the presence of noise.
  file_id: '44037'
  file_name: LNN_project.pdf
  file_size: 576115
  relation: main_file
  title: Discrete Lagrangian Neural Networks with Automatic Symmetry Discovery
file_date_updated: 2023-04-17T08:05:55Z
has_accepted_license: '1'
intvolume: '        56'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://www.sciencedirect.com/science/article/pii/S2405896323018657
oa: '1'
page: 3203-3210
publication: IFAC-PapersOnLine
publication_status: published
publisher: Elsevier
quality_controlled: '1'
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/yanalish/SymDLNN
status: public
title: Discrete Lagrangian Neural Networks with Automatic Symmetry Discovery
type: conference
user_id: '85279'
volume: 56
year: '2023'
...
---
_id: '42163'
abstract:
- lang: eng
  text: 'The article shows how to learn models of dynamical systems from data which
    are governed by an unknown variational PDE. Rather than employing reduction techniques,
    we learn a discrete field theory governed by a discrete Lagrangian density $L_d$
    that is modelled as a neural network. Careful regularisation of the loss function
    for training $L_d$ is necessary to obtain a field theory that is suitable for
    numerical computations: we derive a regularisation term which optimises the solvability
    of the discrete Euler--Lagrange equations. Secondly, we develop a method to find
    solutions to machine learned discrete field theories which constitute travelling
    waves of the underlying continuous PDE.'
author:
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
citation:
  ama: 'Offen C, Ober-Blöbaum S. Learning discrete Lagrangians for variational PDEs
    from data and detection of travelling waves. In: Nielsen F, Barbaresco F, eds.
    <i>Geometric Science of Information</i>. Vol 14071. Lecture Notes in Computer
    Science (LNCS). Springer, Cham.; 2023:569-579. doi:<a href="https://doi.org/10.1007/978-3-031-38271-0_57">10.1007/978-3-031-38271-0_57</a>'
  apa: Offen, C., &#38; Ober-Blöbaum, S. (2023). Learning discrete Lagrangians for
    variational PDEs from data and detection of travelling waves. In F. Nielsen &#38;
    F. Barbaresco (Eds.), <i>Geometric Science of Information</i> (Vol. 14071, pp.
    569–579). Springer, Cham. <a href="https://doi.org/10.1007/978-3-031-38271-0_57">https://doi.org/10.1007/978-3-031-38271-0_57</a>
  bibtex: '@inproceedings{Offen_Ober-Blöbaum_2023, series={Lecture Notes in Computer
    Science (LNCS)}, title={Learning discrete Lagrangians for variational PDEs from
    data and detection of travelling waves}, volume={14071}, DOI={<a href="https://doi.org/10.1007/978-3-031-38271-0_57">10.1007/978-3-031-38271-0_57</a>},
    booktitle={Geometric Science of Information}, publisher={Springer, Cham.}, author={Offen,
    Christian and Ober-Blöbaum, Sina}, editor={Nielsen, F and Barbaresco, F}, year={2023},
    pages={569–579}, collection={Lecture Notes in Computer Science (LNCS)} }'
  chicago: Offen, Christian, and Sina Ober-Blöbaum. “Learning Discrete Lagrangians
    for Variational PDEs from Data and Detection of Travelling Waves.” In <i>Geometric
    Science of Information</i>, edited by F Nielsen and F Barbaresco, 14071:569–79.
    Lecture Notes in Computer Science (LNCS). Springer, Cham., 2023. <a href="https://doi.org/10.1007/978-3-031-38271-0_57">https://doi.org/10.1007/978-3-031-38271-0_57</a>.
  ieee: 'C. Offen and S. Ober-Blöbaum, “Learning discrete Lagrangians for variational
    PDEs from data and detection of travelling waves,” in <i>Geometric Science of
    Information</i>, Saint-Malo, Palais du Grand Large, France, 2023, vol. 14071,
    pp. 569–579, doi: <a href="https://doi.org/10.1007/978-3-031-38271-0_57">10.1007/978-3-031-38271-0_57</a>.'
  mla: Offen, Christian, and Sina Ober-Blöbaum. “Learning Discrete Lagrangians for
    Variational PDEs from Data and Detection of Travelling Waves.” <i>Geometric Science
    of Information</i>, edited by F Nielsen and F Barbaresco, vol. 14071, Springer,
    Cham., 2023, pp. 569–79, doi:<a href="https://doi.org/10.1007/978-3-031-38271-0_57">10.1007/978-3-031-38271-0_57</a>.
  short: 'C. Offen, S. Ober-Blöbaum, in: F. Nielsen, F. Barbaresco (Eds.), Geometric
    Science of Information, Springer, Cham., 2023, pp. 569–579.'
conference:
  end_date: 2023-09-01
  location: Saint-Malo, Palais du Grand Large, France
  name: '  GSI''23 6th International Conference on Geometric Science of Information'
  start_date: 2023-08-30
date_created: 2023-02-16T11:32:48Z
date_updated: 2024-08-12T13:46:29Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.1007/978-3-031-38271-0_57
editor:
- first_name: F
  full_name: Nielsen, F
  last_name: Nielsen
- first_name: F
  full_name: Barbaresco, F
  last_name: Barbaresco
external_id:
  arxiv:
  - '2302.08232 '
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2023-08-02T12:04:17Z
  date_updated: 2023-08-02T12:04:17Z
  description: |-
    The article shows how to learn models of dynamical systems
    from data which are governed by an unknown variational PDE. Rather
    than employing reduction techniques, we learn a discrete field theory
    governed by a discrete Lagrangian density Ld that is modelled as a neural network. Careful regularisation of the loss function for training Ld is
    necessary to obtain a field theory that is suitable for numerical computations: we derive a regularisation term which optimises the solvability of
    the discrete Euler–Lagrange equations. Secondly, we develop a method to
    find solutions to machine learned discrete field theories which constitute
    travelling waves of the underlying continuous PDE.
  file_id: '46273'
  file_name: LDensityLearning.pdf
  file_size: 1938962
  relation: main_file
  title: Learning discrete Lagrangians for variational PDEs from data and detection
    of travelling waves
file_date_updated: 2023-08-02T12:04:17Z
has_accepted_license: '1'
intvolume: '     14071'
keyword:
- System identification
- discrete Lagrangians
- travelling waves
language:
- iso: eng
oa: '1'
page: 569-579
project:
- _id: '52'
  name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication: Geometric Science of Information
publication_identifier:
  eisbn:
  - 978-3-031-38271-0
publication_status: published
publisher: Springer, Cham.
quality_controlled: '1'
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/Christian-Offen/LagrangianDensityML
series_title: Lecture Notes in Computer Science (LNCS)
status: public
title: Learning discrete Lagrangians for variational PDEs from data and detection
  of travelling waves
type: conference
user_id: '85279'
volume: 14071
year: '2023'
...
---
_id: '29240'
abstract:
- lang: eng
  text: "The principle of least action is one of the most fundamental physical principle.
    It says that among all possible motions connecting two points in a phase space,
    the system will exhibit those motions which extremise an action functional. Many
    qualitative features of dynamical systems, such as the presence of conservation
    laws and energy balance equations, are related to the existence of an action functional.
    Incorporating variational structure into learning algorithms for dynamical systems
    is, therefore, crucial in order to make sure that the learned model shares important
    features with the exact physical system. In this paper we show how to incorporate
    variational principles into trajectory predictions of learned dynamical systems.
    The novelty of this work is that (1) our technique relies only on discrete position
    data of observed trajectories. Velocities or conjugate momenta do not need to
    be observed or approximated and no prior knowledge about the form of the variational
    principle is assumed. Instead, they are recovered using backward error analysis.
    (2) Moreover, our technique compensates discretisation errors when trajectories
    are computed from the learned system. This is important when moderate to large
    step-sizes are used and high accuracy is required. For this,\r\nwe introduce and
    rigorously analyse the concept of inverse modified Lagrangians by developing an
    inverse version of variational backward error analysis. (3) Finally, we introduce
    a method to perform system identification from position observations only, based
    on variational backward error analysis."
article_type: original
author:
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
citation:
  ama: Ober-Blöbaum S, Offen C. Variational Learning of Euler–Lagrange Dynamics from
    Data. <i>Journal of Computational and Applied Mathematics</i>. 2023;421:114780.
    doi:<a href="https://doi.org/10.1016/j.cam.2022.114780">10.1016/j.cam.2022.114780</a>
  apa: Ober-Blöbaum, S., &#38; Offen, C. (2023). Variational Learning of Euler–Lagrange
    Dynamics from Data. <i>Journal of Computational and Applied Mathematics</i>, <i>421</i>,
    114780. <a href="https://doi.org/10.1016/j.cam.2022.114780">https://doi.org/10.1016/j.cam.2022.114780</a>
  bibtex: '@article{Ober-Blöbaum_Offen_2023, title={Variational Learning of Euler–Lagrange
    Dynamics from Data}, volume={421}, DOI={<a href="https://doi.org/10.1016/j.cam.2022.114780">10.1016/j.cam.2022.114780</a>},
    journal={Journal of Computational and Applied Mathematics}, publisher={Elsevier},
    author={Ober-Blöbaum, Sina and Offen, Christian}, year={2023}, pages={114780}
    }'
  chicago: 'Ober-Blöbaum, Sina, and Christian Offen. “Variational Learning of Euler–Lagrange
    Dynamics from Data.” <i>Journal of Computational and Applied Mathematics</i> 421
    (2023): 114780. <a href="https://doi.org/10.1016/j.cam.2022.114780">https://doi.org/10.1016/j.cam.2022.114780</a>.'
  ieee: 'S. Ober-Blöbaum and C. Offen, “Variational Learning of Euler–Lagrange Dynamics
    from Data,” <i>Journal of Computational and Applied Mathematics</i>, vol. 421,
    p. 114780, 2023, doi: <a href="https://doi.org/10.1016/j.cam.2022.114780">10.1016/j.cam.2022.114780</a>.'
  mla: Ober-Blöbaum, Sina, and Christian Offen. “Variational Learning of Euler–Lagrange
    Dynamics from Data.” <i>Journal of Computational and Applied Mathematics</i>,
    vol. 421, Elsevier, 2023, p. 114780, doi:<a href="https://doi.org/10.1016/j.cam.2022.114780">10.1016/j.cam.2022.114780</a>.
  short: S. Ober-Blöbaum, C. Offen, Journal of Computational and Applied Mathematics
    421 (2023) 114780.
date_created: 2022-01-11T13:24:00Z
date_updated: 2023-08-10T08:42:39Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.1016/j.cam.2022.114780
external_id:
  arxiv:
  - '2112.12619'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2022-06-28T15:25:50Z
  date_updated: 2022-06-28T15:25:50Z
  description: |-
    The principle of least action is one of the most fundamental physical principle. It says that among all possible motions
    connecting two points in a phase space, the system will exhibit those motions which extremise an action functional.
    Many qualitative features of dynamical systems, such as the presence of conservation laws and energy balance equa-
    tions, are related to the existence of an action functional. Incorporating variational structure into learning algorithms
    for dynamical systems is, therefore, crucial in order to make sure that the learned model shares important features
    with the exact physical system. In this paper we show how to incorporate variational principles into trajectory predic-
    tions of learned dynamical systems. The novelty of this work is that (1) our technique relies only on discrete position
    data of observed trajectories. Velocities or conjugate momenta do not need to be observed or approximated and no
    prior knowledge about the form of the variational principle is assumed. Instead, they are recovered using backward
    error analysis. (2) Moreover, our technique compensates discretisation errors when trajectories are computed from the
    learned system. This is important when moderate to large step-sizes are used and high accuracy is required. For this,
    we introduce and rigorously analyse the concept of inverse modified Lagrangians by developing an inverse version of
    variational backward error analysis. (3) Finally, we introduce a method to perform system identification from position
    observations only, based on variational backward error analysis.
  file_id: '32274'
  file_name: ShadowLagrangian_revision1_journal_style_arxiv.pdf
  file_size: 3640770
  relation: main_file
  title: Variational Learning of Euler–Lagrange Dynamics from Data
file_date_updated: 2022-06-28T15:25:50Z
has_accepted_license: '1'
intvolume: '       421'
keyword:
- Lagrangian learning
- variational backward error analysis
- modified Lagrangian
- variational integrators
- physics informed learning
language:
- iso: eng
oa: '1'
page: '114780'
publication: Journal of Computational and Applied Mathematics
publication_identifier:
  issn:
  - 0377-0427
publication_status: epub_ahead
publisher: Elsevier
quality_controlled: '1'
related_material:
  link:
  - relation: software
    url: https://github.com/Christian-Offen/LagrangianShadowIntegration
status: public
title: Variational Learning of Euler–Lagrange Dynamics from Data
type: journal_article
user_id: '85279'
volume: 421
year: '2023'
...
---
_id: '29236'
abstract:
- lang: eng
  text: The numerical solution of an ordinary differential equation can be interpreted
    as the exact solution of a nearby modified equation. Investigating the behaviour
    of numerical solutions by analysing the modified equation is known as backward
    error analysis. If the original and modified equation share structural properties,
    then the exact and approximate solution share geometric features such as the existence
    of conserved quantities. Conjugate symplectic methods preserve a modified symplectic
    form and a modified Hamiltonian when applied to a Hamiltonian system. We show
    how a blended version of variational and symplectic techniques can be used to
    compute modified symplectic and Hamiltonian structures. In contrast to other approaches,
    our backward error analysis method does not rely on an ansatz but computes the
    structures systematically, provided that a variational formulation of the method
    is known. The technique is illustrated on the example of symmetric linear multistep
    methods with matrix coefficients.
article_type: original
author:
- first_name: Robert
  full_name: McLachlan, Robert
  last_name: McLachlan
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
citation:
  ama: McLachlan R, Offen C. Backward error analysis for conjugate symplectic methods.
    <i>Journal of Geometric Mechanics</i>. 2023;15(1):98-115. doi:<a href="https://doi.org/10.3934/jgm.2023005">10.3934/jgm.2023005</a>
  apa: McLachlan, R., &#38; Offen, C. (2023). Backward error analysis for conjugate
    symplectic methods. <i>Journal of Geometric Mechanics</i>, <i>15</i>(1), 98–115.
    <a href="https://doi.org/10.3934/jgm.2023005">https://doi.org/10.3934/jgm.2023005</a>
  bibtex: '@article{McLachlan_Offen_2023, title={Backward error analysis for conjugate
    symplectic methods}, volume={15}, DOI={<a href="https://doi.org/10.3934/jgm.2023005">10.3934/jgm.2023005</a>},
    number={1}, journal={Journal of Geometric Mechanics}, publisher={AIMS Press},
    author={McLachlan, Robert and Offen, Christian}, year={2023}, pages={98–115} }'
  chicago: 'McLachlan, Robert, and Christian Offen. “Backward Error Analysis for Conjugate
    Symplectic Methods.” <i>Journal of Geometric Mechanics</i> 15, no. 1 (2023): 98–115.
    <a href="https://doi.org/10.3934/jgm.2023005">https://doi.org/10.3934/jgm.2023005</a>.'
  ieee: 'R. McLachlan and C. Offen, “Backward error analysis for conjugate symplectic
    methods,” <i>Journal of Geometric Mechanics</i>, vol. 15, no. 1, pp. 98–115, 2023,
    doi: <a href="https://doi.org/10.3934/jgm.2023005">10.3934/jgm.2023005</a>.'
  mla: McLachlan, Robert, and Christian Offen. “Backward Error Analysis for Conjugate
    Symplectic Methods.” <i>Journal of Geometric Mechanics</i>, vol. 15, no. 1, AIMS
    Press, 2023, pp. 98–115, doi:<a href="https://doi.org/10.3934/jgm.2023005">10.3934/jgm.2023005</a>.
  short: R. McLachlan, C. Offen, Journal of Geometric Mechanics 15 (2023) 98–115.
date_created: 2022-01-11T12:48:39Z
date_updated: 2023-08-10T08:40:30Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.3934/jgm.2023005
external_id:
  arxiv:
  - '2201.03911'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2022-08-12T16:48:59Z
  date_updated: 2022-08-12T16:48:59Z
  description: The numerical solution of an ordinary differential equation can be
    interpreted as the exact solution of a nearby modified equation. Investigating
    the behaviour of numerical solutions by analysing the modified equation is known
    as backward error analysis. If the original and modified equation share structural
    properties, then the exact and approximate solution share geometric features such
    as the existence of conserved quantities. Conjugate symplectic methods preserve
    a modified symplectic form and a modified Hamiltonian when applied to a Hamiltonian
    system. We show how a blended version of variational and symplectic techniques
    can be used to compute modified symplectic and Hamiltonian structures. In contrast
    to other approaches, our backward error analysis method does not rely on an ansatz
    but computes the structures systematically, provided that a variational formulation
    of the method is known. The technique is illustrated on the example of symmetric
    linear multistep methods with matrix coefficients.
  file_id: '32801'
  file_name: BEA_MultiStep_Matrix.pdf
  file_size: 827030
  relation: main_file
  title: Backward error analysis for conjugate symplectic methods
file_date_updated: 2022-08-12T16:48:59Z
has_accepted_license: '1'
intvolume: '        15'
issue: '1'
keyword:
- variational integrators
- backward error analysis
- Euler--Lagrange equations
- multistep methods
- conjugate symplectic methods
language:
- iso: eng
oa: '1'
page: 98-115
publication: Journal of Geometric Mechanics
publication_status: published
publisher: AIMS Press
quality_controlled: '1'
related_material:
  link:
  - relation: software
    url: https://github.com/Christian-Offen/BEAConjugateSymplectic
status: public
title: Backward error analysis for conjugate symplectic methods
type: journal_article
user_id: '85279'
volume: 15
year: '2023'
...
---
_id: '37654'
abstract:
- lang: eng
  text: "Recently, Hamiltonian neural networks (HNN) have been introduced to incorporate
    prior physical knowledge when\r\nlearning the dynamical equations of Hamiltonian
    systems. Hereby, the symplectic system structure is preserved despite\r\nthe data-driven
    modeling approach. However, preserving symmetries requires additional attention.
    In this research, we\r\nenhance the HNN with a Lie algebra framework to detect
    and embed symmetries in the neural network. This approach\r\nallows to simultaneously
    learn the symmetry group action and the total energy of the system. As illustrating
    examples,\r\na pendulum on a cart and a two-body problem from astrodynamics are
    considered."
article_number: '063115'
article_type: original
author:
- first_name: Eva
  full_name: Dierkes, Eva
  last_name: Dierkes
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Kathrin
  full_name: Flaßkamp, Kathrin
  last_name: Flaßkamp
citation:
  ama: Dierkes E, Offen C, Ober-Blöbaum S, Flaßkamp K. Hamiltonian Neural Networks
    with Automatic Symmetry Detection. <i>Chaos</i>. 2023;33(6). doi:<a href="https://doi.org/10.1063/5.0142969">10.1063/5.0142969</a>
  apa: Dierkes, E., Offen, C., Ober-Blöbaum, S., &#38; Flaßkamp, K. (2023). Hamiltonian
    Neural Networks with Automatic Symmetry Detection. <i>Chaos</i>, <i>33</i>(6),
    Article 063115. <a href="https://doi.org/10.1063/5.0142969">https://doi.org/10.1063/5.0142969</a>
  bibtex: '@article{Dierkes_Offen_Ober-Blöbaum_Flaßkamp_2023, title={Hamiltonian Neural
    Networks with Automatic Symmetry Detection}, volume={33}, DOI={<a href="https://doi.org/10.1063/5.0142969">10.1063/5.0142969</a>},
    number={6063115}, journal={Chaos}, publisher={AIP Publishing}, author={Dierkes,
    Eva and Offen, Christian and Ober-Blöbaum, Sina and Flaßkamp, Kathrin}, year={2023}
    }'
  chicago: Dierkes, Eva, Christian Offen, Sina Ober-Blöbaum, and Kathrin Flaßkamp.
    “Hamiltonian Neural Networks with Automatic Symmetry Detection.” <i>Chaos</i>
    33, no. 6 (2023). <a href="https://doi.org/10.1063/5.0142969">https://doi.org/10.1063/5.0142969</a>.
  ieee: 'E. Dierkes, C. Offen, S. Ober-Blöbaum, and K. Flaßkamp, “Hamiltonian Neural
    Networks with Automatic Symmetry Detection,” <i>Chaos</i>, vol. 33, no. 6, Art.
    no. 063115, 2023, doi: <a href="https://doi.org/10.1063/5.0142969">10.1063/5.0142969</a>.'
  mla: Dierkes, Eva, et al. “Hamiltonian Neural Networks with Automatic Symmetry Detection.”
    <i>Chaos</i>, vol. 33, no. 6, 063115, AIP Publishing, 2023, doi:<a href="https://doi.org/10.1063/5.0142969">10.1063/5.0142969</a>.
  short: E. Dierkes, C. Offen, S. Ober-Blöbaum, K. Flaßkamp, Chaos 33 (2023).
date_created: 2023-01-20T09:10:06Z
date_updated: 2023-08-10T08:37:01Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.1063/5.0142969
external_id:
  arxiv:
  - '2301.07928'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2023-04-26T16:20:56Z
  date_updated: 2023-04-26T16:20:56Z
  description: |-
    Incorporating physical system knowledge into data-driven
    system identification has been shown to be beneficial. The
    approach presented in this article combines learning of an
    energy-conserving model from data with detecting a Lie
    group representation of the unknown system symmetry.
    The proposed approach can improve the learned model
    and reveal underlying symmetry simultaneously.
  file_id: '44205'
  file_name: JournalPaper_main.pdf
  file_size: 5200111
  relation: main_file
  title: Hamiltonian Neural Networks with Automatic Symmetry Detection
file_date_updated: 2023-04-26T16:20:56Z
has_accepted_license: '1'
intvolume: '        33'
issue: '6'
language:
- iso: eng
oa: '1'
publication: Chaos
publication_identifier:
  issn:
  - 1054-1500
publication_status: published
publisher: AIP Publishing
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/eva-dierkes/HNN_withSymmetries
status: public
title: Hamiltonian Neural Networks with Automatic Symmetry Detection
type: journal_article
user_id: '85279'
volume: 33
year: '2023'
...
---
_id: '21600'
abstract:
- lang: eng
  text: Many problems in science and engineering require an efficient numerical approximation
    of integrals or solutions to differential equations. For systems with rapidly
    changing dynamics, an equidistant discretization is often inadvisable as it results
    in prohibitively large errors or computational effort. To this end, adaptive schemes,
    such as solvers based on Runge–Kutta pairs, have been developed which adapt the
    step size based on local error estimations at each step. While the classical schemes
    apply very generally and are highly efficient on regular systems, they can behave
    suboptimally when an inefficient step rejection mechanism is triggered by structurally
    complex systems such as chaotic systems. To overcome these issues, we propose
    a method to tailor numerical schemes to the problem class at hand. This is achieved
    by combining simple, classical quadrature rules or ODE solvers with data-driven
    time-stepping controllers. Compared with learning solution operators to ODEs directly,
    it generalizes better to unseen initial data as our approach employs classical
    numerical schemes as base methods. At the same time it can make use of identified
    structures of a problem class and, therefore, outperforms state-of-the-art adaptive
    schemes. Several examples demonstrate superior efficiency. Source code is available
    at https://github.com/lueckem/quadrature-ML.
author:
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
- first_name: Eyke
  full_name: Hüllermeier, Eyke
  id: '48129'
  last_name: Hüllermeier
- first_name: Marvin
  full_name: Lücke, Marvin
  last_name: Lücke
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Karlson
  full_name: Pfannschmidt, Karlson
  id: '13472'
  last_name: Pfannschmidt
  orcid: 0000-0001-9407-7903
citation:
  ama: Dellnitz M, Hüllermeier E, Lücke M, et al. Efficient time stepping for numerical
    integration using reinforcement  learning. <i>SIAM Journal on Scientific Computing</i>.
    2023;45(2):A579-A595. doi:<a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>
  apa: Dellnitz, M., Hüllermeier, E., Lücke, M., Ober-Blöbaum, S., Offen, C., Peitz,
    S., &#38; Pfannschmidt, K. (2023). Efficient time stepping for numerical integration
    using reinforcement  learning. <i>SIAM Journal on Scientific Computing</i>, <i>45</i>(2),
    A579–A595. <a href="https://doi.org/10.1137/21M1412682">https://doi.org/10.1137/21M1412682</a>
  bibtex: '@article{Dellnitz_Hüllermeier_Lücke_Ober-Blöbaum_Offen_Peitz_Pfannschmidt_2023,
    title={Efficient time stepping for numerical integration using reinforcement 
    learning}, volume={45}, DOI={<a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>},
    number={2}, journal={SIAM Journal on Scientific Computing}, author={Dellnitz,
    Michael and Hüllermeier, Eyke and Lücke, Marvin and Ober-Blöbaum, Sina and Offen,
    Christian and Peitz, Sebastian and Pfannschmidt, Karlson}, year={2023}, pages={A579–A595}
    }'
  chicago: 'Dellnitz, Michael, Eyke Hüllermeier, Marvin Lücke, Sina Ober-Blöbaum,
    Christian Offen, Sebastian Peitz, and Karlson Pfannschmidt. “Efficient Time Stepping
    for Numerical Integration Using Reinforcement  Learning.” <i>SIAM Journal on Scientific
    Computing</i> 45, no. 2 (2023): A579–95. <a href="https://doi.org/10.1137/21M1412682">https://doi.org/10.1137/21M1412682</a>.'
  ieee: 'M. Dellnitz <i>et al.</i>, “Efficient time stepping for numerical integration
    using reinforcement  learning,” <i>SIAM Journal on Scientific Computing</i>, vol.
    45, no. 2, pp. A579–A595, 2023, doi: <a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>.'
  mla: Dellnitz, Michael, et al. “Efficient Time Stepping for Numerical Integration
    Using Reinforcement  Learning.” <i>SIAM Journal on Scientific Computing</i>, vol.
    45, no. 2, 2023, pp. A579–95, doi:<a href="https://doi.org/10.1137/21M1412682">10.1137/21M1412682</a>.
  short: M. Dellnitz, E. Hüllermeier, M. Lücke, S. Ober-Blöbaum, C. Offen, S. Peitz,
    K. Pfannschmidt, SIAM Journal on Scientific Computing 45 (2023) A579–A595.
date_created: 2021-04-09T07:59:19Z
date_updated: 2023-08-25T09:24:50Z
ddc:
- '510'
department:
- _id: '101'
- _id: '636'
- _id: '355'
- _id: '655'
doi: 10.1137/21M1412682
external_id:
  arxiv:
  - arXiv:2104.03562
has_accepted_license: '1'
intvolume: '        45'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://epubs.siam.org/doi/reader/10.1137/21M1412682
page: A579-A595
publication: SIAM Journal on Scientific Computing
publication_status: published
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/lueckem/quadrature-ML
status: public
title: Efficient time stepping for numerical integration using reinforcement  learning
type: journal_article
user_id: '47427'
volume: 45
year: '2023'
...
---
_id: '30490'
author:
- first_name: Jacky
  full_name: Cresson, Jacky
  last_name: Cresson
- first_name: Fernando
  full_name: Jiménez, Fernando
  last_name: Jiménez
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
citation:
  ama: Cresson J, Jiménez F, Ober-Blöbaum S. Continuous and discrete Noether’s fractional
    conserved quantities for restricted calculus of variations. <i>AIMS</i>. 2022;14(1):57-89.
  apa: Cresson, J., Jiménez, F., &#38; Ober-Blöbaum, S. (2022). Continuous and discrete
    Noether’s fractional conserved quantities for restricted calculus of variations.
    <i>AIMS</i>, <i>14(1)</i>, 57–89.
  bibtex: '@article{Cresson_Jiménez_Ober-Blöbaum_2022, title={Continuous and discrete
    Noether’s fractional conserved quantities for restricted calculus of variations},
    volume={14(1)}, journal={AIMS}, author={Cresson, Jacky and Jiménez, Fernando and
    Ober-Blöbaum, Sina}, year={2022}, pages={57–89} }'
  chicago: 'Cresson, Jacky, Fernando Jiménez, and Sina Ober-Blöbaum. “Continuous and
    Discrete Noether’s Fractional Conserved Quantities for Restricted Calculus of
    Variations.” <i>AIMS</i> 14(1) (2022): 57–89.'
  ieee: J. Cresson, F. Jiménez, and S. Ober-Blöbaum, “Continuous and discrete Noether’s
    fractional conserved quantities for restricted calculus of variations,” <i>AIMS</i>,
    vol. 14(1), pp. 57–89, 2022.
  mla: Cresson, Jacky, et al. “Continuous and Discrete Noether’s Fractional Conserved
    Quantities for Restricted Calculus of Variations.” <i>AIMS</i>, vol. 14(1), 2022,
    pp. 57–89.
  short: J. Cresson, F. Jiménez, S. Ober-Blöbaum, AIMS 14(1) (2022) 57–89.
date_created: 2022-03-24T12:26:10Z
date_updated: 2022-03-24T12:26:32Z
department:
- _id: '636'
language:
- iso: eng
page: 57-89
publication: AIMS
status: public
title: Continuous and discrete Noether's fractional conserved quantities for restricted
  calculus of variations
type: journal_article
user_id: '15694'
volume: 14(1)
year: '2022'
...
---
_id: '30861'
abstract:
- lang: eng
  text: <jats:title>Abstract</jats:title><jats:p>We consider the problem of maximization
    of metabolite production in bacterial cells formulated as a dynamical optimal
    control problem (DOCP). According to Pontryagin’s maximum principle, optimal solutions
    are concatenations of singular and bang arcs and exhibit the chattering or <jats:italic>Fuller</jats:italic>
    phenomenon, which is problematic for applications. To avoid chattering, we introduce
    a reduced model which is still biologically relevant and retains the important
    structural features of the original problem. Using a combination of analytical
    and numerical methods, we show that the singular arc is dominant in the studied
    DOCPs and exhibits the <jats:italic>turnpike</jats:italic> property. This property
    is further used in order to design simple and realistic suboptimal control strategies.</jats:p>
author:
- first_name: Jean-Baptiste
  full_name: Caillau, Jean-Baptiste
  last_name: Caillau
- first_name: Walid
  full_name: Djema, Walid
  last_name: Djema
- first_name: Jean-Luc
  full_name: Gouzé, Jean-Luc
  last_name: Gouzé
- first_name: Sofya
  full_name: Maslovskaya, Sofya
  id: '87909'
  last_name: Maslovskaya
- first_name: Jean-Baptiste
  full_name: Pomet, Jean-Baptiste
  last_name: Pomet
citation:
  ama: Caillau J-B, Djema W, Gouzé J-L, Maslovskaya S, Pomet J-B. Turnpike Property
    in Optimal Microbial Metabolite Production. <i>Journal of Optimization Theory
    and Applications</i>. Published online 2022. doi:<a href="https://doi.org/10.1007/s10957-022-02023-0">10.1007/s10957-022-02023-0</a>
  apa: Caillau, J.-B., Djema, W., Gouzé, J.-L., Maslovskaya, S., &#38; Pomet, J.-B.
    (2022). Turnpike Property in Optimal Microbial Metabolite Production. <i>Journal
    of Optimization Theory and Applications</i>. <a href="https://doi.org/10.1007/s10957-022-02023-0">https://doi.org/10.1007/s10957-022-02023-0</a>
  bibtex: '@article{Caillau_Djema_Gouzé_Maslovskaya_Pomet_2022, title={Turnpike Property
    in Optimal Microbial Metabolite Production}, DOI={<a href="https://doi.org/10.1007/s10957-022-02023-0">10.1007/s10957-022-02023-0</a>},
    journal={Journal of Optimization Theory and Applications}, publisher={Springer
    Science and Business Media LLC}, author={Caillau, Jean-Baptiste and Djema, Walid
    and Gouzé, Jean-Luc and Maslovskaya, Sofya and Pomet, Jean-Baptiste}, year={2022}
    }'
  chicago: Caillau, Jean-Baptiste, Walid Djema, Jean-Luc Gouzé, Sofya Maslovskaya,
    and Jean-Baptiste Pomet. “Turnpike Property in Optimal Microbial Metabolite Production.”
    <i>Journal of Optimization Theory and Applications</i>, 2022. <a href="https://doi.org/10.1007/s10957-022-02023-0">https://doi.org/10.1007/s10957-022-02023-0</a>.
  ieee: 'J.-B. Caillau, W. Djema, J.-L. Gouzé, S. Maslovskaya, and J.-B. Pomet, “Turnpike
    Property in Optimal Microbial Metabolite Production,” <i>Journal of Optimization
    Theory and Applications</i>, 2022, doi: <a href="https://doi.org/10.1007/s10957-022-02023-0">10.1007/s10957-022-02023-0</a>.'
  mla: Caillau, Jean-Baptiste, et al. “Turnpike Property in Optimal Microbial Metabolite
    Production.” <i>Journal of Optimization Theory and Applications</i>, Springer
    Science and Business Media LLC, 2022, doi:<a href="https://doi.org/10.1007/s10957-022-02023-0">10.1007/s10957-022-02023-0</a>.
  short: J.-B. Caillau, W. Djema, J.-L. Gouzé, S. Maslovskaya, J.-B. Pomet, Journal
    of Optimization Theory and Applications (2022).
date_created: 2022-04-08T17:23:13Z
date_updated: 2022-04-08T18:23:02Z
department:
- _id: '636'
doi: 10.1007/s10957-022-02023-0
keyword:
- Applied Mathematics
- Management Science and Operations Research
- Control and Optimization
language:
- iso: eng
publication: Journal of Optimization Theory and Applications
publication_identifier:
  issn:
  - 0022-3239
  - 1573-2878
publication_status: published
publisher: Springer Science and Business Media LLC
status: public
title: Turnpike Property in Optimal Microbial Metabolite Production
type: journal_article
user_id: '87909'
year: '2022'
...
---
_id: '30733'
abstract:
- lang: eng
  text: Hamilton-Jacobi reachability methods for safety-critical control have been
    well studied, but the safety guarantees derived rely on the accuracy of the numerical
    computation. Thus, it is crucial to understand and account for any inaccuracies
    that occur due to uncertainty in the underlying dynamics and environment as well
    as the induced numerical errors. To this end, we propose a framework for modeling
    the error of the value function inherent in Hamilton-Jacobi reachability using
    a Gaussian process. The derived safety controller can be used in conjuncture with
    arbitrary controllers to provide a safe hybrid control law. The marginal likelihood
    of the Gaussian process then provides a confidence metric used to determine switches
    between a least restrictive controller and a safety controller. We test both the
    prediction as well as the correction capabilities of the presented method in a
    classical pursuit-evasion example.
author:
- first_name: Nikolaus
  full_name: Vertovec, Nikolaus
  id: '93930'
  last_name: Vertovec
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Kostas
  full_name: Margellos, Kostas
  last_name: Margellos
citation:
  ama: 'Vertovec N, Ober-Blöbaum S, Margellos K. Verification of safety critical control
    policies using kernel methods. In: ; 2022:1870-1875.'
  apa: Vertovec, N., Ober-Blöbaum, S., &#38; Margellos, K. (2022). <i>Verification
    of safety critical control policies using kernel methods</i>. 1870–1875.
  bibtex: '@inproceedings{Vertovec_Ober-Blöbaum_Margellos_2022, title={Verification
    of safety critical control policies using kernel methods}, author={Vertovec, Nikolaus
    and Ober-Blöbaum, Sina and Margellos, Kostas}, year={2022}, pages={1870–1875}
    }'
  chicago: Vertovec, Nikolaus, Sina Ober-Blöbaum, and Kostas Margellos. “Verification
    of Safety Critical Control Policies Using Kernel Methods,” 1870–75, 2022.
  ieee: N. Vertovec, S. Ober-Blöbaum, and K. Margellos, “Verification of safety critical
    control policies using kernel methods,” London, 2022, pp. 1870–1875.
  mla: Vertovec, Nikolaus, et al. <i>Verification of Safety Critical Control Policies
    Using Kernel Methods</i>. 2022, pp. 1870–75.
  short: 'N. Vertovec, S. Ober-Blöbaum, K. Margellos, in: 2022, pp. 1870–1875.'
conference:
  end_date: 2022-07-15
  location: London
  name: 2022 European Control Conference (ECC)
  start_date: 2022-07-12
date_created: 2022-03-31T11:14:13Z
date_updated: 2023-11-29T10:00:18Z
ddc:
- '510'
department:
- _id: '636'
has_accepted_license: '1'
language:
- iso: eng
page: 1870-1875
status: public
title: Verification of safety critical control policies using kernel methods
type: conference
user_id: '15694'
year: '2022'
...
---
_id: '44624'
author:
- first_name: Timm
  full_name: Faulwasser, Timm
  last_name: Faulwasser
- first_name: Kathrin
  full_name: Flaßkamp, Kathrin
  last_name: Flaßkamp
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Manuel
  full_name: Schaller, Manuel
  last_name: Schaller
- first_name: Karl
  full_name: Worthmann, Karl
  last_name: Worthmann
citation:
  ama: Faulwasser T, Flaßkamp K, Ober-Blöbaum S, Schaller M, Worthmann K. Manifold
    turnpikes, trims, and symmetries. <i>Mathematics of Control, Signals, and Systems</i>.
    2022;34:759-788.
  apa: Faulwasser, T., Flaßkamp, K., Ober-Blöbaum, S., Schaller, M., &#38; Worthmann,
    K. (2022). Manifold turnpikes, trims, and symmetries. <i>Mathematics of Control,
    Signals, and Systems</i>, <i>34</i>, 759–788.
  bibtex: '@article{Faulwasser_Flaßkamp_Ober-Blöbaum_Schaller_Worthmann_2022, title={Manifold
    turnpikes, trims, and symmetries}, volume={34}, journal={Mathematics of Control,
    Signals, and Systems}, publisher={Springer}, author={Faulwasser, Timm and Flaßkamp,
    Kathrin and Ober-Blöbaum, Sina and Schaller, Manuel and Worthmann, Karl}, year={2022},
    pages={759–788} }'
  chicago: 'Faulwasser, Timm, Kathrin Flaßkamp, Sina Ober-Blöbaum, Manuel Schaller,
    and Karl Worthmann. “Manifold Turnpikes, Trims, and Symmetries.” <i>Mathematics
    of Control, Signals, and Systems</i> 34 (2022): 759–88.'
  ieee: T. Faulwasser, K. Flaßkamp, S. Ober-Blöbaum, M. Schaller, and K. Worthmann,
    “Manifold turnpikes, trims, and symmetries,” <i>Mathematics of Control, Signals,
    and Systems</i>, vol. 34, pp. 759–788, 2022.
  mla: Faulwasser, Timm, et al. “Manifold Turnpikes, Trims, and Symmetries.” <i>Mathematics
    of Control, Signals, and Systems</i>, vol. 34, Springer, 2022, pp. 759–88.
  short: T. Faulwasser, K. Flaßkamp, S. Ober-Blöbaum, M. Schaller, K. Worthmann, Mathematics
    of Control, Signals, and Systems 34 (2022) 759–788.
date_created: 2023-05-08T09:04:06Z
date_updated: 2023-05-08T09:04:26Z
department:
- _id: '636'
intvolume: '        34'
language:
- iso: eng
page: 759-788
publication: Mathematics of Control, Signals, and Systems
publisher: Springer
status: public
title: Manifold turnpikes, trims, and symmetries
type: journal_article
user_id: '15694'
volume: 34
year: '2022'
...
---
_id: '19941'
abstract:
- lang: eng
  text: "In backward error analysis, an approximate solution to an equation is compared
    to the exact solution to a nearby ‘modified’ equation. In numerical ordinary differential
    equations, the two agree up to any power of the step size. If the differential
    equation has a geometric property then the modified equation may share it. In
    this way, known properties of differential equations can be applied to the approximation.
    But for partial differential equations, the known modified equations are of higher
    order, limiting applicability of the theory. Therefore, we study symmetric solutions
    of discretized\r\npartial differential equations that arise from a discrete variational
    principle. These symmetric solutions obey infinite-dimensional functional equations.
    We show that these equations admit second-order modified equations which are Hamiltonian
    and also possess first-order Lagrangians in modified coordinates. The modified
    equation and its associated structures are computed explicitly for the case of
    rotating travelling waves in the nonlinear wave equation."
article_type: original
author:
- first_name: Robert I
  full_name: McLachlan, Robert I
  last_name: McLachlan
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: https://orcid.org/0000-0002-5940-8057
citation:
  ama: McLachlan RI, Offen C. Backward error analysis for variational discretisations
    of partial  differential equations. <i>Journal of Geometric Mechanics</i>. 2022;14(3):447-471.
    doi:<a href="https://doi.org/10.3934/jgm.2022014">10.3934/jgm.2022014</a>
  apa: McLachlan, R. I., &#38; Offen, C. (2022). Backward error analysis for variational
    discretisations of partial  differential equations. <i>Journal of Geometric Mechanics</i>,
    <i>14</i>(3), 447–471. <a href="https://doi.org/10.3934/jgm.2022014">https://doi.org/10.3934/jgm.2022014</a>
  bibtex: '@article{McLachlan_Offen_2022, title={Backward error analysis for variational
    discretisations of partial  differential equations}, volume={14}, DOI={<a href="https://doi.org/10.3934/jgm.2022014">10.3934/jgm.2022014</a>},
    number={3}, journal={Journal of Geometric Mechanics}, publisher={AIMS}, author={McLachlan,
    Robert I and Offen, Christian}, year={2022}, pages={447–471} }'
  chicago: 'McLachlan, Robert I, and Christian Offen. “Backward Error Analysis for
    Variational Discretisations of Partial  Differential Equations.” <i>Journal of
    Geometric Mechanics</i> 14, no. 3 (2022): 447–71. <a href="https://doi.org/10.3934/jgm.2022014">https://doi.org/10.3934/jgm.2022014</a>.'
  ieee: 'R. I. McLachlan and C. Offen, “Backward error analysis for variational discretisations
    of partial  differential equations,” <i>Journal of Geometric Mechanics</i>, vol.
    14, no. 3, pp. 447–471, 2022, doi: <a href="https://doi.org/10.3934/jgm.2022014">10.3934/jgm.2022014</a>.'
  mla: McLachlan, Robert I., and Christian Offen. “Backward Error Analysis for Variational
    Discretisations of Partial  Differential Equations.” <i>Journal of Geometric Mechanics</i>,
    vol. 14, no. 3, AIMS, 2022, pp. 447–71, doi:<a href="https://doi.org/10.3934/jgm.2022014">10.3934/jgm.2022014</a>.
  short: R.I. McLachlan, C. Offen, Journal of Geometric Mechanics 14 (2022) 447–471.
date_created: 2020-10-06T16:33:19Z
date_updated: 2023-08-10T08:44:55Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.3934/jgm.2022014
external_id:
  arxiv:
  - '2006.14172'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2022-06-13T09:11:38Z
  date_updated: 2022-06-13T09:11:38Z
  description: |-
    In backward error analysis, an approximate solution to an equa-
    tion is compared to the exact solution to a nearby ‘modified’ equation. In
    numerical ordinary differential equations, the two agree up to any power of
    the step size. If the differential equation has a geometric property then the
    modified equation may share it. In this way, known properties of differential
    equations can be applied to the approximation. But for partial differential
    equations, the known modified equations are of higher order, limiting appli-
    cability of the theory. Therefore, we study symmetric solutions of discretized
    partial differential equations that arise from a discrete variational principle.
    These symmetric solutions obey infinite-dimensional functional equations. We
    show that these equations admit second-order modified equations which are
    Hamiltonian and also possess first-order Lagrangians in modified coordinates.
    The modified equation and its associated structures are computed explicitly
    for the case of rotating travelling waves in the nonlinear wave equation.
  file_id: '31859'
  file_name: 2_BlendedBEASymmPDE.pdf
  file_size: 1507248
  relation: main_file
  title: Backward error analysis for variational discretisations of PDEs
file_date_updated: 2022-06-13T09:11:38Z
has_accepted_license: '1'
intvolume: '        14'
issue: '3'
language:
- iso: eng
oa: '1'
page: 447 - 471
publication: Journal of Geometric Mechanics
publication_status: published
publisher: AIMS
related_material:
  link:
  - relation: software
    url: https://github.com/Christian-Offen/multisymplectic
status: public
title: Backward error analysis for variational discretisations of partial  differential
  equations
type: journal_article
user_id: '85279'
volume: 14
year: '2022'
...
---
_id: '23382'
abstract:
- lang: eng
  text: Hamiltonian systems are differential equations which describe systems in classical
    mechanics, plasma physics, and sampling problems. They exhibit many structural
    properties, such as a lack of attractors and the presence of conservation laws.
    To predict Hamiltonian dynamics based on discrete trajectory observations, incorporation
    of prior knowledge about Hamiltonian structure greatly improves predictions. This
    is typically done by learning the system's Hamiltonian and then integrating the
    Hamiltonian vector field with a symplectic integrator. For this, however, Hamiltonian
    data needs to be approximated based on the trajectory observations. Moreover,
    the numerical integrator introduces an additional discretisation error. In this
    paper, we show that an inverse modified Hamiltonian structure adapted to the geometric
    integrator can be learned directly from observations. A separate approximation
    step for the Hamiltonian data avoided. The inverse modified data compensates for
    the discretisation error such that the discretisation error is eliminated. The
    technique is developed for Gaussian Processes.
article_type: original
author:
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
citation:
  ama: 'Offen C, Ober-Blöbaum S. Symplectic integration of learned Hamiltonian systems.
    <i>Chaos: An Interdisciplinary Journal of Nonlinear Science</i>. 2022;32(1). doi:<a
    href="https://doi.org/10.1063/5.0065913">10.1063/5.0065913</a>'
  apa: 'Offen, C., &#38; Ober-Blöbaum, S. (2022). Symplectic integration of learned
    Hamiltonian systems. <i>Chaos: An Interdisciplinary Journal of Nonlinear Science</i>,
    <i>32(1)</i>. <a href="https://doi.org/10.1063/5.0065913">https://doi.org/10.1063/5.0065913</a>'
  bibtex: '@article{Offen_Ober-Blöbaum_2022, title={Symplectic integration of learned
    Hamiltonian systems}, volume={32(1)}, DOI={<a href="https://doi.org/10.1063/5.0065913">10.1063/5.0065913</a>},
    journal={Chaos: An Interdisciplinary Journal of Nonlinear Science}, publisher={AIP},
    author={Offen, Christian and Ober-Blöbaum, Sina}, year={2022} }'
  chicago: 'Offen, Christian, and Sina Ober-Blöbaum. “Symplectic Integration of Learned
    Hamiltonian Systems.” <i>Chaos: An Interdisciplinary Journal of Nonlinear Science</i>
    32(1) (2022). <a href="https://doi.org/10.1063/5.0065913">https://doi.org/10.1063/5.0065913</a>.'
  ieee: 'C. Offen and S. Ober-Blöbaum, “Symplectic integration of learned Hamiltonian
    systems,” <i>Chaos: An Interdisciplinary Journal of Nonlinear Science</i>, vol.
    32(1), 2022, doi: <a href="https://doi.org/10.1063/5.0065913">10.1063/5.0065913</a>.'
  mla: 'Offen, Christian, and Sina Ober-Blöbaum. “Symplectic Integration of Learned
    Hamiltonian Systems.” <i>Chaos: An Interdisciplinary Journal of Nonlinear Science</i>,
    vol. 32(1), AIP, 2022, doi:<a href="https://doi.org/10.1063/5.0065913">10.1063/5.0065913</a>.'
  short: 'C. Offen, S. Ober-Blöbaum, Chaos: An Interdisciplinary Journal of Nonlinear
    Science 32(1) (2022).'
date_created: 2021-08-11T08:24:02Z
date_updated: 2023-08-10T08:48:14Z
ddc:
- '510'
department:
- _id: '636'
doi: 10.1063/5.0065913
external_id:
  arxiv:
  - '2108.02492'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2021-12-13T14:56:15Z
  date_updated: 2021-12-13T14:56:15Z
  file_id: '28734'
  file_name: SymplecticShadowIntegration_AIP.pdf
  file_size: 2285059
  relation: main_file
file_date_updated: 2021-12-13T14:56:15Z
has_accepted_license: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://aip.scitation.org/doi/abs/10.1063/5.0065913
oa: '1'
publication: 'Chaos: An Interdisciplinary Journal of Nonlinear Science'
publication_status: published
publisher: AIP
quality_controlled: '1'
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/Christian-Offen/symplectic-shadow-integration
status: public
title: Symplectic integration of learned Hamiltonian systems
type: journal_article
user_id: '85279'
volume: 32(1)
year: '2022'
...
---
_id: '29421'
author:
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: M.
  full_name: Vermeeren, M.
  last_name: Vermeeren
citation:
  ama: 'Ober-Blöbaum S, Vermeeren M. Superconvergence of galerkin variational integrators.
    In: IFAC-PapersOnLine, ed. <i>7th IIFAC Workshop on Lagrangian and Hamiltonian
    Methods for Nonlinear Control LHMNC</i>. Vol 54(19). ; 2021:327-333.'
  apa: 'Ober-Blöbaum, S., &#38; Vermeeren, M. (2021). Superconvergence of galerkin
    variational integrators. In IFAC-PapersOnLine (Ed.), <i>7th IIFAC Workshop on
    Lagrangian and Hamiltonian Methods for Nonlinear Control LHMNC: Vol. 54(19)</i>
    (pp. 327–333).'
  bibtex: '@inproceedings{Ober-Blöbaum_Vermeeren_2021, title={Superconvergence of
    galerkin variational integrators}, volume={54(19)}, booktitle={7th IIFAC Workshop
    on Lagrangian and Hamiltonian Methods for Nonlinear Control LHMNC}, author={Ober-Blöbaum,
    Sina and Vermeeren, M.}, editor={IFAC-PapersOnLine}, year={2021}, pages={327–333}
    }'
  chicago: Ober-Blöbaum, Sina, and M. Vermeeren. “Superconvergence of Galerkin Variational
    Integrators.” In <i>7th IIFAC Workshop on Lagrangian and Hamiltonian Methods for
    Nonlinear Control LHMNC</i>, edited by IFAC-PapersOnLine, 54(19):327–33, 2021.
  ieee: S. Ober-Blöbaum and M. Vermeeren, “Superconvergence of galerkin variational
    integrators,” in <i>7th IIFAC Workshop on Lagrangian and Hamiltonian Methods for
    Nonlinear Control LHMNC</i>, 2021, vol. 54(19), pp. 327–333.
  mla: Ober-Blöbaum, Sina, and M. Vermeeren. “Superconvergence of Galerkin Variational
    Integrators.” <i>7th IIFAC Workshop on Lagrangian and Hamiltonian Methods for
    Nonlinear Control LHMNC</i>, edited by IFAC-PapersOnLine, vol. 54(19), 2021, pp.
    327–33.
  short: 'S. Ober-Blöbaum, M. Vermeeren, in: IFAC-PapersOnLine (Ed.), 7th IIFAC Workshop
    on Lagrangian and Hamiltonian Methods for Nonlinear Control LHMNC, 2021, pp. 327–333.'
corporate_editor:
- IFAC-PapersOnLine
date_created: 2022-01-18T14:27:56Z
date_updated: 2022-01-21T13:36:53Z
department:
- _id: '636'
language:
- iso: eng
page: 327-333
publication: 7th IIFAC Workshop on Lagrangian and Hamiltonian Methods for Nonlinear
  Control LHMNC
status: public
title: Superconvergence of galerkin variational integrators
type: conference
user_id: '15694'
volume: 54(19)
year: '2021'
...
---
_id: '29543'
article_number: '109804'
author:
- first_name: Walid
  full_name: Djema, Walid
  last_name: Djema
- first_name: Laetitia
  full_name: Giraldi, Laetitia
  last_name: Giraldi
- first_name: Sofya
  full_name: Maslovskaya, Sofya
  id: '87909'
  last_name: Maslovskaya
- first_name: Olivier
  full_name: Bernard, Olivier
  last_name: Bernard
citation:
  ama: Djema W, Giraldi L, Maslovskaya S, Bernard O. Turnpike features in optimal
    selection of species represented by quota models. <i>Automatica</i>. 2021;132.
    doi:<a href="https://doi.org/10.1016/j.automatica.2021.109804">10.1016/j.automatica.2021.109804</a>
  apa: Djema, W., Giraldi, L., Maslovskaya, S., &#38; Bernard, O. (2021). Turnpike
    features in optimal selection of species represented by quota models. <i>Automatica</i>,
    <i>132</i>, Article 109804. <a href="https://doi.org/10.1016/j.automatica.2021.109804">https://doi.org/10.1016/j.automatica.2021.109804</a>
  bibtex: '@article{Djema_Giraldi_Maslovskaya_Bernard_2021, title={Turnpike features
    in optimal selection of species represented by quota models}, volume={132}, DOI={<a
    href="https://doi.org/10.1016/j.automatica.2021.109804">10.1016/j.automatica.2021.109804</a>},
    number={109804}, journal={Automatica}, publisher={Elsevier BV}, author={Djema,
    Walid and Giraldi, Laetitia and Maslovskaya, Sofya and Bernard, Olivier}, year={2021}
    }'
  chicago: Djema, Walid, Laetitia Giraldi, Sofya Maslovskaya, and Olivier Bernard.
    “Turnpike Features in Optimal Selection of Species Represented by Quota Models.”
    <i>Automatica</i> 132 (2021). <a href="https://doi.org/10.1016/j.automatica.2021.109804">https://doi.org/10.1016/j.automatica.2021.109804</a>.
  ieee: 'W. Djema, L. Giraldi, S. Maslovskaya, and O. Bernard, “Turnpike features
    in optimal selection of species represented by quota models,” <i>Automatica</i>,
    vol. 132, Art. no. 109804, 2021, doi: <a href="https://doi.org/10.1016/j.automatica.2021.109804">10.1016/j.automatica.2021.109804</a>.'
  mla: Djema, Walid, et al. “Turnpike Features in Optimal Selection of Species Represented
    by Quota Models.” <i>Automatica</i>, vol. 132, 109804, Elsevier BV, 2021, doi:<a
    href="https://doi.org/10.1016/j.automatica.2021.109804">10.1016/j.automatica.2021.109804</a>.
  short: W. Djema, L. Giraldi, S. Maslovskaya, O. Bernard, Automatica 132 (2021).
date_created: 2022-01-26T13:13:06Z
date_updated: 2022-01-26T13:15:33Z
department:
- _id: '636'
doi: 10.1016/j.automatica.2021.109804
intvolume: '       132'
keyword:
- Electrical and Electronic Engineering
- Control and Systems Engineering
language:
- iso: eng
publication: Automatica
publication_identifier:
  issn:
  - 0005-1098
publication_status: published
publisher: Elsevier BV
status: public
title: Turnpike features in optimal selection of species represented by quota models
type: journal_article
user_id: '87909'
volume: 132
year: '2021'
...
---
_id: '22894'
abstract:
- lang: eng
  text: "The first order optimality conditions of optimal control problems (OCPs)
    can\r\nbe regarded as boundary value problems for Hamiltonian systems. Variational
    or\r\nsymplectic discretisation methods are classically known for their excellent\r\nlong
    term behaviour. As boundary value problems are posed on intervals of\r\nfixed,
    moderate length, it is not immediately clear whether methods can profit\r\nfrom
    structure preservation in this context. When parameters are present,\r\nsolutions
    can undergo bifurcations, for instance, two solutions can merge and\r\nannihilate
    one another as parameters are varied. We will show that generic\r\nbifurcations
    of an OCP are preserved under discretisation when the OCP is\r\neither directly
    discretised to a discrete OCP (direct method) or translated\r\ninto a Hamiltonian
    boundary value problem using first order necessary\r\nconditions of optimality
    which is then solved using a symplectic integrator\r\n(indirect method). Moreover,
    certain bifurcations break when a non-symplectic\r\nscheme is used. The general
    phenomenon is illustrated on the example of a cut\r\nlocus of an ellipsoid."
author:
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
citation:
  ama: Offen C, Ober-Blöbaum S. Bifurcation preserving discretisations of optimal
    control problems. 2021;54(19):334-339. doi:<a href="https://doi.org/10.1016/j.ifacol.2021.11.099">https://doi.org/10.1016/j.ifacol.2021.11.099</a>
  apa: 'Offen, C., &#38; Ober-Blöbaum, S. (2021). <i>Bifurcation preserving discretisations
    of optimal control problems: Vol. 54(19)</i> (pp. 334–339). <a href="https://doi.org/10.1016/j.ifacol.2021.11.099">https://doi.org/10.1016/j.ifacol.2021.11.099</a>'
  bibtex: '@article{Offen_Ober-Blöbaum_2021, series={IFAC-PapersOnLine}, title={Bifurcation
    preserving discretisations of optimal control problems}, volume={54(19)}, DOI={<a
    href="https://doi.org/10.1016/j.ifacol.2021.11.099">https://doi.org/10.1016/j.ifacol.2021.11.099</a>},
    author={Offen, Christian and Ober-Blöbaum, Sina}, year={2021}, pages={334–339},
    collection={IFAC-PapersOnLine} }'
  chicago: Offen, Christian, and Sina Ober-Blöbaum. “Bifurcation Preserving Discretisations
    of Optimal Control Problems.” IFAC-PapersOnLine, 2021. <a href="https://doi.org/10.1016/j.ifacol.2021.11.099">https://doi.org/10.1016/j.ifacol.2021.11.099</a>.
  ieee: 'C. Offen and S. Ober-Blöbaum, “Bifurcation preserving discretisations of
    optimal control problems,” vol. 54(19). pp. 334–339, 2021, doi: <a href="https://doi.org/10.1016/j.ifacol.2021.11.099">https://doi.org/10.1016/j.ifacol.2021.11.099</a>.'
  mla: Offen, Christian, and Sina Ober-Blöbaum. <i>Bifurcation Preserving Discretisations
    of Optimal Control Problems</i>. 2021, pp. 334–39, doi:<a href="https://doi.org/10.1016/j.ifacol.2021.11.099">https://doi.org/10.1016/j.ifacol.2021.11.099</a>.
  short: C. Offen, S. Ober-Blöbaum, 54(19) (2021) 334–339.
conference:
  end_date: 2021-10-13
  location: Berlin, Germany
  name: 7th IFAC Workshop on Lagrangian and Hamiltonian Methods for Nonlinear Control,
    LHMNC 2021
  start_date: 2021-10-11
date_created: 2021-07-29T09:38:32Z
date_updated: 2023-11-29T10:19:41Z
ddc:
- '510'
department:
- _id: '636'
doi: https://doi.org/10.1016/j.ifacol.2021.11.099
external_id:
  arxiv:
  - '2107.13853'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2021-07-29T09:37:49Z
  date_updated: 2021-07-29T09:37:49Z
  file_id: '22895'
  file_name: ifacconf.pdf
  file_size: 3125220
  relation: main_file
file_date_updated: 2021-07-29T09:37:49Z
has_accepted_license: '1'
keyword:
- optimal control
- catastrophe theory
- bifurcations
- variational methods
- symplectic integrators
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://www.sciencedirect.com/science/article/pii/S2405896321021236
oa: '1'
page: 334-339
publication_identifier:
  issn:
  - 2405-8963
publication_status: published
quality_controlled: '1'
related_material:
  link:
  - description: GitHub/Zenodo
    relation: software
    url: https://doi.org/10.5281/zenodo.4562664
series_title: IFAC-PapersOnLine
status: public
title: Bifurcation preserving discretisations of optimal control problems
type: conference
user_id: '15694'
volume: 54(19)
year: '2021'
...
---
_id: '21572'
author:
- first_name: Steffen
  full_name: Ridderbusch, Steffen
  last_name: Ridderbusch
- first_name: Christian
  full_name: Offen, Christian
  id: '85279'
  last_name: Offen
  orcid: 0000-0002-5940-8057
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
- first_name: Paul
  full_name: Goulart, Paul
  last_name: Goulart
citation:
  ama: 'Ridderbusch S, Offen C, Ober-Blöbaum S, Goulart P. Learning ODE Models with
    Qualitative Structure Using Gaussian Processes . In: <i>2021 60th IEEE Conference
    on Decision and Control (CDC)</i>. IEEE; 2021:2896. doi:<a href="https://doi.org/10.1109/CDC45484.2021.9683426">10.1109/CDC45484.2021.9683426</a>'
  apa: Ridderbusch, S., Offen, C., Ober-Blöbaum, S., &#38; Goulart, P. (2021). Learning
    ODE Models with Qualitative Structure Using Gaussian Processes . <i>2021 60th
    IEEE Conference on Decision and Control (CDC)</i>, 2896. <a href="https://doi.org/10.1109/CDC45484.2021.9683426">https://doi.org/10.1109/CDC45484.2021.9683426</a>
  bibtex: '@inproceedings{Ridderbusch_Offen_Ober-Blöbaum_Goulart_2021, title={Learning
    ODE Models with Qualitative Structure Using Gaussian Processes }, DOI={<a href="https://doi.org/10.1109/CDC45484.2021.9683426">10.1109/CDC45484.2021.9683426</a>},
    booktitle={2021 60th IEEE Conference on Decision and Control (CDC)}, publisher={IEEE},
    author={Ridderbusch, Steffen and Offen, Christian and Ober-Blöbaum, Sina and Goulart,
    Paul}, year={2021}, pages={2896} }'
  chicago: Ridderbusch, Steffen, Christian Offen, Sina Ober-Blöbaum, and Paul Goulart.
    “Learning ODE Models with Qualitative Structure Using Gaussian Processes .” In
    <i>2021 60th IEEE Conference on Decision and Control (CDC)</i>, 2896. IEEE, 2021.
    <a href="https://doi.org/10.1109/CDC45484.2021.9683426">https://doi.org/10.1109/CDC45484.2021.9683426</a>.
  ieee: 'S. Ridderbusch, C. Offen, S. Ober-Blöbaum, and P. Goulart, “Learning ODE
    Models with Qualitative Structure Using Gaussian Processes ,” in <i>2021 60th
    IEEE Conference on Decision and Control (CDC)</i>, Austin, TX, USA, 2021, p. 2896,
    doi: <a href="https://doi.org/10.1109/CDC45484.2021.9683426">10.1109/CDC45484.2021.9683426</a>.'
  mla: Ridderbusch, Steffen, et al. “Learning ODE Models with Qualitative Structure
    Using Gaussian Processes .” <i>2021 60th IEEE Conference on Decision and Control
    (CDC)</i>, IEEE, 2021, p. 2896, doi:<a href="https://doi.org/10.1109/CDC45484.2021.9683426">10.1109/CDC45484.2021.9683426</a>.
  short: 'S. Ridderbusch, C. Offen, S. Ober-Blöbaum, P. Goulart, in: 2021 60th IEEE
    Conference on Decision and Control (CDC), IEEE, 2021, p. 2896.'
conference:
  end_date: 2021-12-17
  location: Austin, TX, USA
  name: 60th IEEE Conference on Decision and Control (CDC)
  start_date: 2021-12-14
date_created: 2021-03-30T10:27:44Z
date_updated: 2023-11-29T10:24:55Z
department:
- _id: '636'
doi: 10.1109/CDC45484.2021.9683426
external_id:
  arxiv:
  - '2011.05364'
language:
- iso: eng
page: '2896'
publication: 2021 60th IEEE Conference on Decision and Control (CDC)
publication_identifier:
  eisbn:
  - 978-1-6654-3659-5
publication_status: published
publisher: IEEE
related_material:
  link:
  - description: GitHub
    relation: software
    url: https://github.com/Crown421/StructureGPs-paper
status: public
title: 'Learning ODE Models with Qualitative Structure Using Gaussian Processes '
type: conference
user_id: '15694'
year: '2021'
...
