---
_id: '64865'
abstract:
- lang: eng
  text: We provide a method to systematically construct vector fields for which the
    dynamics display transitions corresponding to a desired hierarchical connection
    structure. This structure is given as a finite set of directed graphs $\mathbf{G}_1,\dotsc,\mathbf{G}_N$
    (the lower level), together with another digraph $\mathbfΓ$ on $N$ vertices (the
    top level). The dynamic realizations of $\mathbf{G}_1,\dotsc,\mathbf{G}_N$ are
    heteroclinic networks and they can be thought of as individual connection patterns
    on a given set of states. Edges in $\mathbfΓ$ correspond to transitions between
    these different patterns. In our construction, the connections given through $\mathbfΓ$
    are not heteroclinic, but excitable with zero threshold. This describes a dynamical
    transition between two invariant sets where every $δ$-neighborhood of the first
    set contains an initial condition with $ω$-limit in the second set. Thus, we prove
    a theorem that allows the systematic creation of hierarchical networks that are
    excitable on the top level, and heteroclinic on the lower level. Our results modify
    and extend the simplex realization method by Ashwin & Postlethwaite.
author:
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
- first_name: Alexander
  full_name: Lohse, Alexander
  last_name: Lohse
citation:
  ama: von der Gracht S, Lohse A. Design of Hierarchical Excitable Networks. <i>arXiv:260306157</i>.
    Published online 2026.
  apa: von der Gracht, S., &#38; Lohse, A. (2026). Design of Hierarchical Excitable
    Networks. In <i>arXiv:2603.06157</i>.
  bibtex: '@article{von der Gracht_Lohse_2026, title={Design of Hierarchical Excitable
    Networks}, journal={arXiv:2603.06157}, author={von der Gracht, Sören and Lohse,
    Alexander}, year={2026} }'
  chicago: Gracht, Sören von der, and Alexander Lohse. “Design of Hierarchical Excitable
    Networks.” <i>ArXiv:2603.06157</i>, 2026.
  ieee: S. von der Gracht and A. Lohse, “Design of Hierarchical Excitable Networks,”
    <i>arXiv:2603.06157</i>. 2026.
  mla: von der Gracht, Sören, and Alexander Lohse. “Design of Hierarchical Excitable
    Networks.” <i>ArXiv:2603.06157</i>, 2026.
  short: S. von der Gracht, A. Lohse, ArXiv:2603.06157 (2026).
date_created: 2026-03-09T08:22:58Z
date_updated: 2026-03-09T08:26:49Z
ddc:
- '510'
department:
- _id: '101'
- _id: '841'
external_id:
  arxiv:
  - '2603.06157'
file:
- access_level: closed
  content_type: application/pdf
  creator: svdg
  date_created: 2026-03-09T08:26:04Z
  date_updated: 2026-03-09T08:26:04Z
  file_id: '64866'
  file_name: design-of-hierarchical-excitable-networks.pdf
  file_size: 5179491
  relation: main_file
  success: 1
file_date_updated: 2026-03-09T08:26:04Z
has_accepted_license: '1'
language:
- iso: eng
publication: arXiv:2603.06157
related_material:
  link:
  - relation: research_paper
    url: https://s-vdg.github.io/publication/design-of-hierarchical-excitable-networks/design-of-hierarchical-excitable-networks.pdf
status: public
title: Design of Hierarchical Excitable Networks
type: preprint
user_id: '97359'
year: '2026'
...
---
_id: '64979'
abstract:
- lang: eng
  text: We investigate homogeneous coupled cell systems with high-dimensional internal
    dynamics. In many studies on network dynamics, the analysis is restricted to networks
    with one-dimensional internal dynamics. Here, we show how symmetry explains the
    relation between dynamical behavior of systems with one-dimensional internal dynamics
    and with higher dimensional internal dynamics, when the underlying network topology
    is the same. Fundamental networks of homogeneous coupled cell systems (B. Rink,
    J. Sanders. Coupled Cell Networks and Their Hidden Symmetries. SIAM J. Math. Anal.
    46.2 (2014)) can be expressed in terms of monoid representations, which uniquely
    decompose into indecomposable subrepresentations. In the high-dimensional internal
    dynamics case, these subrepresentations are isomorphic to multiple copies of those
    one computes in the one-dimensional internal dynamics case. This has interesting
    implications for possible center subspaces in bifurcation analysis. We describe
    the effect on steady state and Hopf bifurcations in l-parameter families of network
    vector fields. The main results in that regard are that (1) generic one-parameter
    steady state bifurcations are qualitatively independent of the dimension of the
    internal dynamics and that, (2) in order to observe all generic l-parameter bifurcations
    that may occur for internal dynamics of any dimension, the internal dynamics has
    to be at least l-dimensional for steady state bifurcations and 2l-dimensional
    for Hopf bifurcations. Furthermore, we illustrate how additional structure in
    the network can be exploited to obtain even greater understanding of bifurcation
    scenarios in the high-dimensional case beyond qualitative statements about the
    collective dynamics. One-parameter steady state bifurcations in feedforward networks
    exhibit an unusual amplification in the asymptotic growth rates of individual
    cells, when these are one-dimensional (S. von der Gracht, E. Nijholt, B. Rink.
    Amplified steady state bifurcations in feedforward networks. Nonlinearity 35.4
    (2022)). As another main result, we prove that (3) the same cells exhibit this
    amplifying effect with the same growth rates when the internal dynamics is high-dimensional.
article_number: '118196'
article_type: original
author:
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
- first_name: Eddie
  full_name: Nijholt, Eddie
  last_name: Nijholt
- first_name: Bob
  full_name: Rink, Bob
  last_name: Rink
citation:
  ama: von der Gracht S, Nijholt E, Rink B. Homogeneous coupled cell systems with
    high-dimensional internal dynamics. <i>Chaos, Solitons &#38; Fractals</i>. 2026;208.
    doi:<a href="https://doi.org/10.1016/j.chaos.2026.118196">10.1016/j.chaos.2026.118196</a>
  apa: von der Gracht, S., Nijholt, E., &#38; Rink, B. (2026). Homogeneous coupled
    cell systems with high-dimensional internal dynamics. <i>Chaos, Solitons &#38;
    Fractals</i>, <i>208</i>, Article 118196. <a href="https://doi.org/10.1016/j.chaos.2026.118196">https://doi.org/10.1016/j.chaos.2026.118196</a>
  bibtex: '@article{von der Gracht_Nijholt_Rink_2026, title={Homogeneous coupled cell
    systems with high-dimensional internal dynamics}, volume={208}, DOI={<a href="https://doi.org/10.1016/j.chaos.2026.118196">10.1016/j.chaos.2026.118196</a>},
    number={118196}, journal={Chaos, Solitons &#38; Fractals}, publisher={Elsevier
    BV}, author={von der Gracht, Sören and Nijholt, Eddie and Rink, Bob}, year={2026}
    }'
  chicago: Gracht, Sören von der, Eddie Nijholt, and Bob Rink. “Homogeneous Coupled
    Cell Systems with High-Dimensional Internal Dynamics.” <i>Chaos, Solitons &#38;
    Fractals</i> 208 (2026). <a href="https://doi.org/10.1016/j.chaos.2026.118196">https://doi.org/10.1016/j.chaos.2026.118196</a>.
  ieee: 'S. von der Gracht, E. Nijholt, and B. Rink, “Homogeneous coupled cell systems
    with high-dimensional internal dynamics,” <i>Chaos, Solitons &#38; Fractals</i>,
    vol. 208, Art. no. 118196, 2026, doi: <a href="https://doi.org/10.1016/j.chaos.2026.118196">10.1016/j.chaos.2026.118196</a>.'
  mla: von der Gracht, Sören, et al. “Homogeneous Coupled Cell Systems with High-Dimensional
    Internal Dynamics.” <i>Chaos, Solitons &#38; Fractals</i>, vol. 208, 118196, Elsevier
    BV, 2026, doi:<a href="https://doi.org/10.1016/j.chaos.2026.118196">10.1016/j.chaos.2026.118196</a>.
  short: S. von der Gracht, E. Nijholt, B. Rink, Chaos, Solitons &#38; Fractals 208
    (2026).
date_created: 2026-03-16T08:39:07Z
date_updated: 2026-03-16T08:42:56Z
ddc:
- '510'
department:
- _id: '101'
- _id: '841'
doi: 10.1016/j.chaos.2026.118196
external_id:
  arxiv:
  - '2510.06740'
file:
- access_level: closed
  content_type: application/pdf
  creator: svdg
  date_created: 2026-03-16T08:40:04Z
  date_updated: 2026-03-16T08:40:04Z
  file_id: '64980'
  file_name: homogeneous-coupled-cell-systems-with-high-dimensional-internal-dynamics.pdf
  file_size: 1951746
  relation: main_file
  success: 1
file_date_updated: 2026-03-16T08:40:04Z
has_accepted_license: '1'
intvolume: '       208'
keyword:
- Coupled cell systems
- Network dynamics
- Dimension reduction
- Bifurcation theory
- Symmetry
- Monoid representation theory
language:
- iso: eng
publication: Chaos, Solitons & Fractals
publication_identifier:
  issn:
  - 0960-0779
publication_status: published
publisher: Elsevier BV
status: public
title: Homogeneous coupled cell systems with high-dimensional internal dynamics
type: journal_article
user_id: '97359'
volume: 208
year: '2026'
...
---
_id: '60048'
author:
- first_name: Raphael
  full_name: Gerlach, Raphael
  id: '32655'
  last_name: Gerlach
  orcid: 0009-0002-4750-2051
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
citation:
  ama: 'Gerlach R, von der Gracht S, Dellnitz M. On the Dynamical Hierarchy in Gathering
    Protocols with Circulant Topologies. In: <i>Lecture Notes in Computer Science</i>.
    Springer Nature Switzerland; 2025. doi:<a href="https://doi.org/10.1007/978-3-031-91736-3_19">10.1007/978-3-031-91736-3_19</a>'
  apa: Gerlach, R., von der Gracht, S., &#38; Dellnitz, M. (2025). On the Dynamical
    Hierarchy in Gathering Protocols with Circulant Topologies. In <i>Lecture Notes
    in Computer Science</i>. Springer Nature Switzerland. <a href="https://doi.org/10.1007/978-3-031-91736-3_19">https://doi.org/10.1007/978-3-031-91736-3_19</a>
  bibtex: '@inbook{Gerlach_von der Gracht_Dellnitz_2025, place={Cham}, title={On the Dynamical
    Hierarchy in Gathering Protocols with Circulant Topologies}, DOI={<a href="https://doi.org/10.1007/978-3-031-91736-3_19">10.1007/978-3-031-91736-3_19</a>},
    booktitle={Lecture Notes in Computer Science}, publisher={Springer Nature Switzerland},
    author={Gerlach, Raphael and von der Gracht, Sören and Dellnitz, Michael}, year={2025}
    }'
  chicago: 'Gerlach, Raphael, Sören von der Gracht, and Michael Dellnitz. “On the Dynamical
    Hierarchy in Gathering Protocols with Circulant Topologies.” In <i>Lecture Notes
    in Computer Science</i>. Cham: Springer Nature Switzerland, 2025. <a href="https://doi.org/10.1007/978-3-031-91736-3_19">https://doi.org/10.1007/978-3-031-91736-3_19</a>.'
  ieee: 'R. Gerlach, S. von der Gracht, and M. Dellnitz, “On the Dynamical Hierarchy
    in Gathering Protocols with Circulant Topologies,” in <i>Lecture Notes in Computer
    Science</i>, Cham: Springer Nature Switzerland, 2025.'
  mla: Gerlach, Raphael, et al. “On the Dynamical Hierarchy in Gathering Protocols
    with Circulant Topologies.” <i>Lecture Notes in Computer Science</i>, Springer
    Nature Switzerland, 2025, doi:<a href="https://doi.org/10.1007/978-3-031-91736-3_19">10.1007/978-3-031-91736-3_19</a>.
  short: 'R. Gerlach, S. von der Gracht, M. Dellnitz, in: Lecture Notes in Computer
    Science, Springer Nature Switzerland, Cham, 2025.'
date_created: 2025-05-27T08:17:03Z
date_updated: 2025-05-27T08:22:42Z
department:
- _id: '101'
doi: 10.1007/978-3-031-91736-3_19
external_id:
  arxiv:
  - '2503.07576'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: ' ArXiv:2503.07576'
oa: '1'
place: Cham
project:
- _id: '106'
  grant_number: '453112019'
  name: 'Algorithmen für Schwarmrobotik: Verteiltes Rechnen trifft Dynamische Systeme'
publication: Lecture Notes in Computer Science
publication_identifier:
  isbn:
  - '9783031917356'
  - '9783031917363'
  issn:
  - 0302-9743
  - 1611-3349
publication_status: published
publisher: Springer Nature Switzerland
status: public
title: On the Dynamical Hierarchy in Gathering Protocols with Circulant Topologies
type: book_chapter
user_id: '32655'
year: '2025'
...
---
_id: '56298'
abstract:
- lang: eng
  text: "In the general pattern formation (GPF) problem, a swarm of simple autonomous,\r\ndisoriented
    robots must form a given pattern. The robots' simplicity imply a\r\nstrong limitation:
    When the initial configuration is rotationally symmetric,\r\nonly patterns with
    a similar symmetry can be formed [Yamashita, Suzyuki; TCS\r\n2010]. The only known
    algorithm to form large patterns with limited visibility\r\nand without memory
    requires the robots to start in a near-gathering (a swarm of\r\nconstant diameter)
    [Hahn et al.; SAND 2024]. However, not only do we not know\r\nany near-gathering
    algorithm guaranteed to preserve symmetry but most natural\r\ngathering strategies
    trivially increase symmetries [Castenow et al.; OPODIS\r\n2022].\r\n  Thus, we
    study near-gathering without changing the swarm's rotational\r\nsymmetry for disoriented,
    oblivious robots with limited visibility (the\r\nOBLOT-model, see [Flocchini et
    al.; 2019]). We introduce a technique based on\r\nthe theory of dynamical systems
    to analyze how a given algorithm affects\r\nsymmetry and provide sufficient conditions
    for symmetry preservation. Until\r\nnow, it was unknown whether the considered
    OBLOT-model allows for any\r\nnon-trivial algorithm that always preserves symmetry.
    Our first result shows\r\nthat a variant of Go-to-the-Average always preserves
    symmetry but may sometimes\r\nlead to multiple, unconnected near-gathering clusters.
    Our second result is a\r\nsymmetry-preserving near-gathering algorithm that works
    on swarms with a convex\r\nboundary (the outer boundary of the unit disc graph)
    and without holes (circles\r\nof diameter 1 inside the boundary without any robots)."
author:
- first_name: Raphael
  full_name: Gerlach, Raphael
  id: '32655'
  last_name: Gerlach
  orcid: 0009-0002-4750-2051
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
- first_name: Christopher
  full_name: Hahn, Christopher
  last_name: Hahn
- first_name: Jonas
  full_name: Harbig, Jonas
  id: '47213'
  last_name: Harbig
- first_name: Peter
  full_name: Kling, Peter
  last_name: Kling
citation:
  ama: 'Gerlach R, von der Gracht S, Hahn C, Harbig J, Kling P. Symmetry Preservation
    in Swarms of Oblivious Robots with Limited  Visibility. In: Bonomi S, Galletta
    L, Rivière  Etienne, Schiavoni  Valerio, eds. <i>28th International Conference
    on Principles of Distributed Systems (OPODIS 2024)</i>. Vol 324. Leibniz International
    Proceedings in Informatics (LIPIcs). Schloss Dagstuhl -- Leibniz-Zentrum für Informatik;
    2025. doi:<a href="https://doi.org/10.4230/LIPIcs.OPODIS.2024.13">10.4230/LIPIcs.OPODIS.2024.13</a>'
  apa: Gerlach, R., von der Gracht, S., Hahn, C., Harbig, J., &#38; Kling, P. (2025).
    Symmetry Preservation in Swarms of Oblivious Robots with Limited  Visibility.
    In S. Bonomi, L. Galletta,  Etienne Rivière, &#38;  Valerio Schiavoni (Eds.),
    <i>28th International Conference on Principles of Distributed Systems (OPODIS
    2024)</i> (Vol. 324). Schloss Dagstuhl -- Leibniz-Zentrum für Informatik. <a href="https://doi.org/10.4230/LIPIcs.OPODIS.2024.13">https://doi.org/10.4230/LIPIcs.OPODIS.2024.13</a>
  bibtex: '@inproceedings{Gerlach_von der Gracht_Hahn_Harbig_Kling_2025, series={Leibniz
    International Proceedings in Informatics (LIPIcs)}, title={Symmetry Preservation
    in Swarms of Oblivious Robots with Limited  Visibility}, volume={324}, DOI={<a
    href="https://doi.org/10.4230/LIPIcs.OPODIS.2024.13">10.4230/LIPIcs.OPODIS.2024.13</a>},
    booktitle={28th International Conference on Principles of Distributed Systems
    (OPODIS 2024)}, publisher={Schloss Dagstuhl -- Leibniz-Zentrum für Informatik},
    author={Gerlach, Raphael and von der Gracht, Sören and Hahn, Christopher and Harbig,
    Jonas and Kling, Peter}, editor={Bonomi, Silvia and Galletta, Letterio and Rivière,  Etienne
    and Schiavoni,  Valerio}, year={2025}, collection={Leibniz International Proceedings
    in Informatics (LIPIcs)} }'
  chicago: Gerlach, Raphael, Sören von der Gracht, Christopher Hahn, Jonas Harbig,
    and Peter Kling. “Symmetry Preservation in Swarms of Oblivious Robots with Limited 
    Visibility.” In <i>28th International Conference on Principles of Distributed
    Systems (OPODIS 2024)</i>, edited by Silvia Bonomi, Letterio Galletta,  Etienne
    Rivière, and  Valerio Schiavoni, Vol. 324. Leibniz International Proceedings in
    Informatics (LIPIcs). Schloss Dagstuhl -- Leibniz-Zentrum für Informatik, 2025.
    <a href="https://doi.org/10.4230/LIPIcs.OPODIS.2024.13">https://doi.org/10.4230/LIPIcs.OPODIS.2024.13</a>.
  ieee: 'R. Gerlach, S. von der Gracht, C. Hahn, J. Harbig, and P. Kling, “Symmetry
    Preservation in Swarms of Oblivious Robots with Limited  Visibility,” in <i>28th
    International Conference on Principles of Distributed Systems (OPODIS 2024)</i>,
    Lucca, Italy, 2025, vol. 324, doi: <a href="https://doi.org/10.4230/LIPIcs.OPODIS.2024.13">10.4230/LIPIcs.OPODIS.2024.13</a>.'
  mla: Gerlach, Raphael, et al. “Symmetry Preservation in Swarms of Oblivious Robots
    with Limited  Visibility.” <i>28th International Conference on Principles of Distributed
    Systems (OPODIS 2024)</i>, edited by Silvia Bonomi et al., vol. 324, Schloss Dagstuhl
    -- Leibniz-Zentrum für Informatik, 2025, doi:<a href="https://doi.org/10.4230/LIPIcs.OPODIS.2024.13">10.4230/LIPIcs.OPODIS.2024.13</a>.
  short: 'R. Gerlach, S. von der Gracht, C. Hahn, J. Harbig, P. Kling, in: S. Bonomi,
    L. Galletta,  Etienne Rivière,  Valerio Schiavoni (Eds.), 28th International Conference
    on Principles of Distributed Systems (OPODIS 2024), Schloss Dagstuhl -- Leibniz-Zentrum
    für Informatik, 2025.'
conference:
  end_date: 2024-12-13
  location: Lucca, Italy
  name: 28th International Conference on Principles of Distributed Systems (OPODIS
    2024)
  start_date: 2024-12-11
date_created: 2024-10-01T13:29:43Z
date_updated: 2025-01-09T11:39:19Z
department:
- _id: '101'
doi: 10.4230/LIPIcs.OPODIS.2024.13
editor:
- first_name: Silvia
  full_name: Bonomi, Silvia
  last_name: Bonomi
- first_name: Letterio
  full_name: Galletta, Letterio
  last_name: Galletta
- first_name: ' Etienne'
  full_name: Rivière,  Etienne
  last_name: Rivière
- first_name: ' Valerio'
  full_name: Schiavoni,  Valerio
  last_name: Schiavoni
external_id:
  arxiv:
  - '2409.19277'
intvolume: '       324'
keyword:
- Swarm Algorithm
- Swarm Robots
- Distributed Algorithm
- Pattern Formation
- Limited Visibility
- Oblivious
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/2409.19277
oa: '1'
project:
- _id: '106'
  grant_number: '453112019'
  name: 'Algorithmen für Schwarmrobotik: Verteiltes Rechnen trifft Dynamische Systeme'
publication: 28th International Conference on Principles of Distributed Systems (OPODIS
  2024)
publication_identifier:
  isbn:
  - 978-3-95977-360-7
  issn:
  - 1868-8969
publication_status: published
publisher: Schloss Dagstuhl -- Leibniz-Zentrum für Informatik
series_title: Leibniz International Proceedings in Informatics (LIPIcs)
status: public
title: Symmetry Preservation in Swarms of Oblivious Robots with Limited  Visibility
type: conference
user_id: '97359'
volume: 324
year: '2025'
...
---
_id: '58953'
abstract:
- lang: eng
  text: In this article, we investigate symmetry properties of distributed systems
    of mobile robots. We consider a swarm of n robots in the OBLOT model and analyze
    their collective Fsync dynamics using of equivariant dynamical systems theory.
    To this end, we show that the corresponding evolution function commutes with rotational
    and reflective transformations of R^2. These form a group that is isomorphic to
    O(2) x S_n, the product group of the orthogonal group and the permutation on n
    elements. The theory of equivariant dynamical systems is used to deduce a hierarchy
    along which symmetries of a robot swarm can potentially increase following an
    arbitrary protocol. By decoupling the Look phase from the Compute and Move phases
    in the mathematical description of an LCM cycle, this hierarchy can be characterized
    in terms of automorphisms of connectivity graphs. In particular, we find all possible
    types of symmetry increase, if the decoupled Compute and Move phase is invertible.
    Finally, we apply our results to protocols which induce state-dependent linear
    dynamics, where the reduced system consisting of only the Compute and Move phase
    is linear.
author:
- first_name: Raphael
  full_name: Gerlach, Raphael
  id: '32655'
  last_name: Gerlach
  orcid: 0009-0002-4750-2051
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
citation:
  ama: Gerlach R, von der Gracht S. Analyzing Symmetries of Swarms of Mobile Robots
    Using Equivariant  Dynamical Systems. <i>arXiv:250307576</i>. Published online
    2025.
  apa: Gerlach, R., &#38; von der Gracht, S. (2025). Analyzing Symmetries of Swarms
    of Mobile Robots Using Equivariant  Dynamical Systems. In <i>arXiv:2503.07576</i>.
  bibtex: '@article{Gerlach_von der Gracht_2025, title={Analyzing Symmetries of Swarms
    of Mobile Robots Using Equivariant  Dynamical Systems}, journal={arXiv:2503.07576},
    author={Gerlach, Raphael and von der Gracht, Sören}, year={2025} }'
  chicago: Gerlach, Raphael, and Sören von der Gracht. “Analyzing Symmetries of Swarms
    of Mobile Robots Using Equivariant  Dynamical Systems.” <i>ArXiv:2503.07576</i>,
    2025.
  ieee: R. Gerlach and S. von der Gracht, “Analyzing Symmetries of Swarms of Mobile
    Robots Using Equivariant  Dynamical Systems,” <i>arXiv:2503.07576</i>. 2025.
  mla: Gerlach, Raphael, and Sören von der Gracht. “Analyzing Symmetries of Swarms
    of Mobile Robots Using Equivariant  Dynamical Systems.” <i>ArXiv:2503.07576</i>,
    2025.
  short: R. Gerlach, S. von der Gracht, ArXiv:2503.07576 (2025).
date_created: 2025-03-11T08:21:05Z
date_updated: 2025-03-11T08:53:02Z
ddc:
- '004'
department:
- _id: '101'
external_id:
  arxiv:
  - '2503.07576'
file:
- access_level: open_access
  content_type: application/pdf
  creator: svdg
  date_created: 2025-03-11T08:27:32Z
  date_updated: 2025-03-11T08:27:32Z
  file_id: '58954'
  file_name: Analyzing_Symmetries_of_Swarms_of_Mobile_Robots_Using_Equivariant_Dynamical_Systems.pdf
  file_size: 812198
  relation: main_file
file_date_updated: 2025-03-11T08:27:32Z
has_accepted_license: '1'
keyword:
- dynamical systems
- coupled systems
- distributed computing
- robot swarms
- autonomous mobile robots
- symmetry
- equivariant dynamics
language:
- iso: eng
oa: '1'
page: '23'
project:
- _id: '106'
  grant_number: '453112019'
  name: 'Algorithmen für Schwarmrobotik: Verteiltes Rechnen trifft Dynamische Systeme'
publication: arXiv:2503.07576
status: public
title: Analyzing Symmetries of Swarms of Mobile Robots Using Equivariant  Dynamical
  Systems
type: preprint
user_id: '97359'
year: '2025'
...
---
_id: '57472'
abstract:
- lang: eng
  text: In this paper we introduce, in a Hilbert space setting, a second order dynamical
    system with asymptotically vanishing damping and vanishing Tikhonov regularization
    that approaches a multiobjective optimization problem with convex and differentiable
    components of the objective function. Trajectory solutions are shown to exist
    in finite dimensions. We prove fast convergence of the function values, quantified
    in terms of a merit function. Based on the regime considered, we establish both
    weak and, in some cases, strong convergence of trajectory solutions toward a weak
    Pareto optimal solution. To achieve this, we apply Tikhonov regularization individually
    to each component of the objective function. This work extends results from single
    objective convex optimization into the multiobjective setting.
author:
- first_name: Radu Ioan
  full_name: Bot, Radu Ioan
  last_name: Bot
- first_name: Konstantin
  full_name: Sonntag, Konstantin
  id: '56399'
  last_name: Sonntag
  orcid: https://orcid.org/0000-0003-3384-3496
citation:
  ama: Bot RI, Sonntag K. Inertial dynamics with vanishing Tikhonov regularization
    for multobjective optimization. <i>Journal of Mathematical Analysis and Applications</i>.
    Published online 2025.
  apa: Bot, R. I., &#38; Sonntag, K. (2025). Inertial dynamics with vanishing Tikhonov
    regularization for multobjective optimization. <i>Journal of Mathematical Analysis
    and Applications</i>.
  bibtex: '@article{Bot_Sonntag_2025, title={Inertial dynamics with vanishing Tikhonov
    regularization for multobjective optimization}, journal={Journal of Mathematical
    Analysis and Applications}, author={Bot, Radu Ioan and Sonntag, Konstantin}, year={2025}
    }'
  chicago: Bot, Radu Ioan, and Konstantin Sonntag. “Inertial Dynamics with Vanishing
    Tikhonov Regularization for Multobjective Optimization.” <i>Journal of Mathematical
    Analysis and Applications</i>, 2025.
  ieee: R. I. Bot and K. Sonntag, “Inertial dynamics with vanishing Tikhonov regularization
    for multobjective optimization,” <i>Journal of Mathematical Analysis and Applications</i>,
    2025.
  mla: Bot, Radu Ioan, and Konstantin Sonntag. “Inertial Dynamics with Vanishing Tikhonov
    Regularization for Multobjective Optimization.” <i>Journal of Mathematical Analysis
    and Applications</i>, 2025.
  short: R.I. Bot, K. Sonntag, Journal of Mathematical Analysis and Applications (2025).
date_created: 2024-11-28T08:58:17Z
date_updated: 2025-10-16T11:56:36Z
ddc:
- '510'
department:
- _id: '101'
- _id: '530'
- _id: '655'
external_id:
  arxiv:
  - '2411.18422'
file:
- access_level: open_access
  content_type: application/pdf
  creator: sonntagk
  date_created: 2024-11-28T08:58:00Z
  date_updated: 2024-11-28T08:58:00Z
  file_id: '57473'
  file_name: Inertial dynamics with vanishing Tikhonov regularization for multobjective
    optimization.pdf
  file_size: 4291134
  relation: main_file
file_date_updated: 2024-11-28T08:58:00Z
has_accepted_license: '1'
keyword:
- Pareto optimization
- Lyapunov analysis
- gradient-like dynamical systems
- inertial dynamics
- asymptotic vanishing damping
- Tikhonov regularization
- strong convergence
language:
- iso: eng
main_file_link:
- url: https://arxiv.org/pdf/2411.18422
oa: '1'
publication: Journal of Mathematical Analysis and Applications
status: public
title: Inertial dynamics with vanishing Tikhonov regularization for multobjective
  optimization
type: journal_article
user_id: '56399'
year: '2025'
...
---
_id: '62750'
abstract:
- lang: eng
  text: 'Diese Dissertation enthält Beiträge zum Bereich der Mehrzieloptimierung mit
    einem Fokus auf unbeschränkten Problemen, die auf einem allgemeinen Hilbertraum
    definiert sind. Für Mehrzieloptimierungsprobleme mit lokal Lipschitz-stetigen
    Zielfunktionen definieren wir ein multikriterielles Subdifferential, das wir erstmals
    im Kontext allgemeiner Hilberträume analysieren. Aufbauend auf diesen theoretischen
    Untersuchungen präsentieren wir ein Abstiegsverfahren, bei welchem in jeder Iteration
    eine Abstiegsrichtung mittels einer numerischen Approximation des multikriteriellen
    Subdifferentials bestimmt wird. Im Kontext konvexer, stetig differenzierbarer
    Zielfunktionen mit Lipschitz-stetigen Gradienten, führen wir eine Familie von
    dynamischen Gradientensystemen mit Trägheitsterm ein, die bekannte kontinuierliche
    Systeme aus der skalaren Optimierung verallgemeinern. Wir stellen drei neue Systeme
    vor: eines mit konstanter Dämpfung, eines mit asymptotisch abnehmender Dämpfung
    und eines, das zusätzlich eine zeitabhängige Tikhonov-Regularisierung beinhaltet.
    Aufbauend auf den Untersuchungen der neuen dynamischen Gradientensysteme, entwickeln
    wir ein beschleunigtes Gradientenverfahren zur Mehrzieloptimierung, das auf einer
    Diskretisierung des multikriteriellen Gradientensystems mit asymptotisch abnehmender
    Dämpfung beruht. Das hergeleitete Verfahren bewahrt die günstigen Konvergenzeigenschaften
    des kontinuierlichen Systems und erreicht eine schnellere Konvergenz als klassische
    Verfahren.'
- lang: eng
  text: 'This dissertation contributes to the field of multiobjective optimization,
    with a focus on unconstrained problems formulated in a general Hilbert space.
    For multiobjective optimization problems with locally Lipschitz continuous objective
    functions, we define a multiobjective subdifferential, which we analyze for the
    first time in the context of general Hilbert spaces. Building on these theoretical
    investigations, we present a descent method in which, at each iteration, a descent
    direction is determined via a numerical approximation of the multiobjective subdifferential.
    In the setting of convex, continuously differentiable objective functions with
    Lipschitz continuous gradients, we introduce a family of inertial gradient dynamical
    systems that generalize well-known continuous-time systems from scalar optimization.
    We present three novel systems: one with constant damping, one with asymptotic
    vanishing damping, and one combining vanishing damping with time-dependent Tikhonov
    regularization. Building on the investigation of the novel gradient dynamical
    systems, we develop an accelerated gradient method for multiobjective optimization
    via discretization of the multiobjective gradient system with asymptotic vanishing
    damping. The proposed method retains the favorable convergence properties of the
    continuous system while achieving faster convergence than standard approaches,
    such as classical methods.'
author:
- first_name: Konstantin
  full_name: Sonntag, Konstantin
  id: '56399'
  last_name: Sonntag
  orcid: https://orcid.org/0000-0003-3384-3496
citation:
  ama: Sonntag K. <i>First-Order Methods and Gradient Dynamical Systems for Multiobjective
    Optimization</i>. Paderborn University; 2025. doi:<a href="https://doi.org/10.17619/UNIPB/1-2457">10.17619/UNIPB/1-2457</a>
  apa: Sonntag, K. (2025). <i>First-order methods and gradient dynamical systems for
    multiobjective optimization</i>. Paderborn University. <a href="https://doi.org/10.17619/UNIPB/1-2457">https://doi.org/10.17619/UNIPB/1-2457</a>
  bibtex: '@book{Sonntag_2025, title={First-order methods and gradient dynamical systems
    for multiobjective optimization}, DOI={<a href="https://doi.org/10.17619/UNIPB/1-2457">10.17619/UNIPB/1-2457</a>},
    publisher={Paderborn University}, author={Sonntag, Konstantin}, year={2025} }'
  chicago: Sonntag, Konstantin. <i>First-Order Methods and Gradient Dynamical Systems
    for Multiobjective Optimization</i>. Paderborn University, 2025. <a href="https://doi.org/10.17619/UNIPB/1-2457">https://doi.org/10.17619/UNIPB/1-2457</a>.
  ieee: K. Sonntag, <i>First-order methods and gradient dynamical systems for multiobjective
    optimization</i>. Paderborn University, 2025.
  mla: Sonntag, Konstantin. <i>First-Order Methods and Gradient Dynamical Systems
    for Multiobjective Optimization</i>. Paderborn University, 2025, doi:<a href="https://doi.org/10.17619/UNIPB/1-2457">10.17619/UNIPB/1-2457</a>.
  short: K. Sonntag, First-Order Methods and Gradient Dynamical Systems for Multiobjective
    Optimization, Paderborn University, 2025.
date_created: 2025-12-03T06:55:01Z
date_updated: 2025-12-03T07:04:36Z
ddc:
- '510'
department:
- _id: '101'
- _id: '530'
doi: 10.17619/UNIPB/1-2457
has_accepted_license: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://digital.ub.uni-paderborn.de/hs/download/pdf/8141881
oa: '1'
publisher: Paderborn University
status: public
supervisor:
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
- first_name: Sina
  full_name: Ober-Blöbaum, Sina
  id: '16494'
  last_name: Ober-Blöbaum
title: First-order methods and gradient dynamical systems for multiobjective optimization
type: dissertation
user_id: '56399'
year: '2025'
...
---
_id: '51208'
abstract:
- lang: eng
  text: <jats:title>Abstract</jats:title><jats:p>Approximation of subdifferentials
    is one of the main tasks when computing descent directions for nonsmooth optimization
    problems. In this article, we propose a bisection method for weakly lower semismooth
    functions which is able to compute new subgradients that improve a given approximation
    in case a direction with insufficient descent was computed. Combined with a recently
    proposed deterministic gradient sampling approach, this yields a deterministic
    and provably convergent way to approximate subdifferentials for computing descent
    directions.</jats:p>
author:
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
citation:
  ama: Gebken B. A note on the convergence of deterministic gradient sampling in nonsmooth
    optimization. <i>Computational Optimization and Applications</i>. Published online
    2024. doi:<a href="https://doi.org/10.1007/s10589-024-00552-0">10.1007/s10589-024-00552-0</a>
  apa: Gebken, B. (2024). A note on the convergence of deterministic gradient sampling
    in nonsmooth optimization. <i>Computational Optimization and Applications</i>.
    <a href="https://doi.org/10.1007/s10589-024-00552-0">https://doi.org/10.1007/s10589-024-00552-0</a>
  bibtex: '@article{Gebken_2024, title={A note on the convergence of deterministic
    gradient sampling in nonsmooth optimization}, DOI={<a href="https://doi.org/10.1007/s10589-024-00552-0">10.1007/s10589-024-00552-0</a>},
    journal={Computational Optimization and Applications}, publisher={Springer Science
    and Business Media LLC}, author={Gebken, Bennet}, year={2024} }'
  chicago: Gebken, Bennet. “A Note on the Convergence of Deterministic Gradient Sampling
    in Nonsmooth Optimization.” <i>Computational Optimization and Applications</i>,
    2024. <a href="https://doi.org/10.1007/s10589-024-00552-0">https://doi.org/10.1007/s10589-024-00552-0</a>.
  ieee: 'B. Gebken, “A note on the convergence of deterministic gradient sampling
    in nonsmooth optimization,” <i>Computational Optimization and Applications</i>,
    2024, doi: <a href="https://doi.org/10.1007/s10589-024-00552-0">10.1007/s10589-024-00552-0</a>.'
  mla: Gebken, Bennet. “A Note on the Convergence of Deterministic Gradient Sampling
    in Nonsmooth Optimization.” <i>Computational Optimization and Applications</i>,
    Springer Science and Business Media LLC, 2024, doi:<a href="https://doi.org/10.1007/s10589-024-00552-0">10.1007/s10589-024-00552-0</a>.
  short: B. Gebken, Computational Optimization and Applications (2024).
date_created: 2024-02-07T07:23:23Z
date_updated: 2024-02-08T08:05:54Z
department:
- _id: '101'
doi: 10.1007/s10589-024-00552-0
keyword:
- Applied Mathematics
- Computational Mathematics
- Control and Optimization
language:
- iso: eng
publication: Computational Optimization and Applications
publication_identifier:
  issn:
  - 0926-6003
  - 1573-2894
publication_status: published
publisher: Springer Science and Business Media LLC
status: public
title: A note on the convergence of deterministic gradient sampling in nonsmooth optimization
type: journal_article
user_id: '32643'
year: '2024'
...
---
_id: '46019'
abstract:
- lang: eng
  text: We derive efficient algorithms to compute weakly Pareto optimal solutions
    for smooth, convex and unconstrained multiobjective optimization problems in general
    Hilbert spaces. To this end, we define a novel inertial gradient-like dynamical
    system in the multiobjective setting, which trajectories converge weakly to Pareto
    optimal solutions. Discretization of this system yields an inertial multiobjective
    algorithm which generates sequences that converge weakly to Pareto optimal solutions.
    We employ Nesterov acceleration to define an algorithm with an improved convergence
    rate compared to the plain multiobjective steepest descent method (Algorithm 1).
    A further improvement in terms of efficiency is achieved by avoiding the solution
    of a quadratic subproblem to compute a common step direction for all objective
    functions, which is usually required in first-order methods. Using a different
    discretization of our inertial gradient-like dynamical system, we obtain an accelerated
    multiobjective gradient method that does not require the solution of a subproblem
    in each step (Algorithm 2). While this algorithm does not converge in general,
    it yields good results on test problems while being faster than standard steepest
    descent.
author:
- first_name: Konstantin
  full_name: Sonntag, Konstantin
  id: '56399'
  last_name: Sonntag
  orcid: https://orcid.org/0000-0003-3384-3496
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Sonntag K, Peitz S. Fast Multiobjective Gradient Methods with Nesterov Acceleration
    via Inertial Gradient-Like Systems. <i>Journal of Optimization Theory and Applications</i>.
    Published online 2024. doi:<a href="https://doi.org/10.1007/s10957-024-02389-3">10.1007/s10957-024-02389-3</a>
  apa: Sonntag, K., &#38; Peitz, S. (2024). Fast Multiobjective Gradient Methods with
    Nesterov Acceleration via Inertial Gradient-Like Systems. <i>Journal of Optimization
    Theory and Applications</i>. <a href="https://doi.org/10.1007/s10957-024-02389-3">https://doi.org/10.1007/s10957-024-02389-3</a>
  bibtex: '@article{Sonntag_Peitz_2024, title={Fast Multiobjective Gradient Methods
    with Nesterov Acceleration via Inertial Gradient-Like Systems}, DOI={<a href="https://doi.org/10.1007/s10957-024-02389-3">10.1007/s10957-024-02389-3</a>},
    journal={Journal of Optimization Theory and Applications}, publisher={Springer},
    author={Sonntag, Konstantin and Peitz, Sebastian}, year={2024} }'
  chicago: Sonntag, Konstantin, and Sebastian Peitz. “Fast Multiobjective Gradient
    Methods with Nesterov Acceleration via Inertial Gradient-Like Systems.” <i>Journal
    of Optimization Theory and Applications</i>, 2024. <a href="https://doi.org/10.1007/s10957-024-02389-3">https://doi.org/10.1007/s10957-024-02389-3</a>.
  ieee: 'K. Sonntag and S. Peitz, “Fast Multiobjective Gradient Methods with Nesterov
    Acceleration via Inertial Gradient-Like Systems,” <i>Journal of Optimization Theory
    and Applications</i>, 2024, doi: <a href="https://doi.org/10.1007/s10957-024-02389-3">10.1007/s10957-024-02389-3</a>.'
  mla: Sonntag, Konstantin, and Sebastian Peitz. “Fast Multiobjective Gradient Methods
    with Nesterov Acceleration via Inertial Gradient-Like Systems.” <i>Journal of
    Optimization Theory and Applications</i>, Springer, 2024, doi:<a href="https://doi.org/10.1007/s10957-024-02389-3">10.1007/s10957-024-02389-3</a>.
  short: K. Sonntag, S. Peitz, Journal of Optimization Theory and Applications (2024).
date_created: 2023-07-12T06:35:58Z
date_updated: 2024-02-21T10:13:33Z
department:
- _id: '101'
- _id: '655'
doi: 10.1007/s10957-024-02389-3
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://link.springer.com/content/pdf/10.1007/s10957-024-02389-3.pdf
oa: '1'
publication: Journal of Optimization Theory and Applications
publication_status: published
publisher: Springer
status: public
title: Fast Multiobjective Gradient Methods with Nesterov Acceleration via Inertial
  Gradient-Like Systems
type: journal_article
user_id: '56399'
year: '2024'
...
---
_id: '51334'
abstract:
- lang: eng
  text: The efficient optimization method for locally Lipschitz continuous multiobjective
    optimization problems from [1] is extended from finite-dimensional problems to
    general Hilbert spaces. The method iteratively computes Pareto critical points,
    where in each iteration, an approximation of the subdifferential is computed in
    an efficient manner and then used to compute a common descent direction for all
    objective functions. To prove convergence, we present some new optimality results
    for nonsmooth multiobjective optimization problems in Hilbert spaces. Using these,
    we can show that every accumulation point of the sequence generated by our algorithm
    is Pareto critical under common assumptions. Computational efficiency for finding
    Pareto critical points is numerically demonstrated for multiobjective optimal
    control of an obstacle problem.
author:
- first_name: Konstantin
  full_name: Sonntag, Konstantin
  id: '56399'
  last_name: Sonntag
  orcid: https://orcid.org/0000-0003-3384-3496
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Georg
  full_name: Müller, Georg
  last_name: Müller
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Stefan
  full_name: Volkwein, Stefan
  last_name: Volkwein
citation:
  ama: Sonntag K, Gebken B, Müller G, Peitz S, Volkwein S. A Descent Method for Nonsmooth
    Multiobjective Optimization in Hilbert Spaces. <i>arXiv:240206376</i>. Published
    online 2024.
  apa: Sonntag, K., Gebken, B., Müller, G., Peitz, S., &#38; Volkwein, S. (2024).
    A Descent Method for Nonsmooth Multiobjective Optimization in Hilbert Spaces.
    In <i>arXiv:2402.06376</i>.
  bibtex: '@article{Sonntag_Gebken_Müller_Peitz_Volkwein_2024, title={A Descent Method
    for Nonsmooth Multiobjective Optimization in Hilbert Spaces}, journal={arXiv:2402.06376},
    author={Sonntag, Konstantin and Gebken, Bennet and Müller, Georg and Peitz, Sebastian
    and Volkwein, Stefan}, year={2024} }'
  chicago: Sonntag, Konstantin, Bennet Gebken, Georg Müller, Sebastian Peitz, and
    Stefan Volkwein. “A Descent Method for Nonsmooth Multiobjective Optimization in
    Hilbert Spaces.” <i>ArXiv:2402.06376</i>, 2024.
  ieee: K. Sonntag, B. Gebken, G. Müller, S. Peitz, and S. Volkwein, “A Descent Method
    for Nonsmooth Multiobjective Optimization in Hilbert Spaces,” <i>arXiv:2402.06376</i>.
    2024.
  mla: Sonntag, Konstantin, et al. “A Descent Method for Nonsmooth Multiobjective
    Optimization in Hilbert Spaces.” <i>ArXiv:2402.06376</i>, 2024.
  short: K. Sonntag, B. Gebken, G. Müller, S. Peitz, S. Volkwein, ArXiv:2402.06376
    (2024).
date_created: 2024-02-13T09:35:26Z
date_updated: 2024-02-21T10:21:03Z
department:
- _id: '101'
- _id: '655'
external_id:
  arxiv:
  - "\t2402.06376"
has_accepted_license: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/2402.06376
oa: '1'
publication: arXiv:2402.06376
status: public
title: A Descent Method for Nonsmooth Multiobjective Optimization in Hilbert Spaces
type: preprint
user_id: '56399'
year: '2024'
...
---
_id: '52726'
abstract:
- lang: eng
  text: Heteroclinic structures organize global features of dynamical systems. We
    analyse whether heteroclinic structures can arise in network dynamics with higher-order
    interactions which describe the nonlinear interactions between three or more units.
    We find that while commonly analysed model equations such as network dynamics
    on undirected hypergraphs may be useful to describe local dynamics such as cluster
    synchronization, they give rise to obstructions that allow to design of heteroclinic
    structures in phase space. By contrast, directed hypergraphs break the homogeneity
    and lead to vector fields that support heteroclinic structures.
article_type: original
author:
- first_name: Christian
  full_name: Bick, Christian
  last_name: Bick
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
citation:
  ama: Bick C, von der Gracht S. Heteroclinic dynamics in network dynamical systems
    with higher-order interactions. <i>Journal of Complex Networks</i>. 2024;12(2).
    doi:<a href="https://doi.org/10.1093/comnet/cnae009">10.1093/comnet/cnae009</a>
  apa: Bick, C., &#38; von der Gracht, S. (2024). Heteroclinic dynamics in network
    dynamical systems with higher-order interactions. <i>Journal of Complex Networks</i>,
    <i>12</i>(2). <a href="https://doi.org/10.1093/comnet/cnae009">https://doi.org/10.1093/comnet/cnae009</a>
  bibtex: '@article{Bick_von der Gracht_2024, title={Heteroclinic dynamics in network
    dynamical systems with higher-order interactions}, volume={12}, DOI={<a href="https://doi.org/10.1093/comnet/cnae009">10.1093/comnet/cnae009</a>},
    number={2}, journal={Journal of Complex Networks}, publisher={Oxford University
    Press (OUP)}, author={Bick, Christian and von der Gracht, Sören}, year={2024}
    }'
  chicago: Bick, Christian, and Sören von der Gracht. “Heteroclinic Dynamics in Network
    Dynamical Systems with Higher-Order Interactions.” <i>Journal of Complex Networks</i>
    12, no. 2 (2024). <a href="https://doi.org/10.1093/comnet/cnae009">https://doi.org/10.1093/comnet/cnae009</a>.
  ieee: 'C. Bick and S. von der Gracht, “Heteroclinic dynamics in network dynamical
    systems with higher-order interactions,” <i>Journal of Complex Networks</i>, vol.
    12, no. 2, 2024, doi: <a href="https://doi.org/10.1093/comnet/cnae009">10.1093/comnet/cnae009</a>.'
  mla: Bick, Christian, and Sören von der Gracht. “Heteroclinic Dynamics in Network
    Dynamical Systems with Higher-Order Interactions.” <i>Journal of Complex Networks</i>,
    vol. 12, no. 2, Oxford University Press (OUP), 2024, doi:<a href="https://doi.org/10.1093/comnet/cnae009">10.1093/comnet/cnae009</a>.
  short: C. Bick, S. von der Gracht, Journal of Complex Networks 12 (2024).
date_created: 2024-03-22T09:04:57Z
date_updated: 2024-03-22T09:11:53Z
ddc:
- '510'
department:
- _id: '101'
doi: 10.1093/comnet/cnae009
external_id:
  arxiv:
  - '2309.02006'
file:
- access_level: closed
  content_type: application/pdf
  creator: svdg
  date_created: 2024-03-22T09:06:07Z
  date_updated: 2024-03-22T09:06:07Z
  file_id: '52728'
  file_name: heteroclinic-dynamics-in-network-dynamical-systems-with-higher-order-interactions.pdf
  file_size: 649155
  relation: main_file
  success: 1
file_date_updated: 2024-03-22T09:06:07Z
has_accepted_license: '1'
intvolume: '        12'
issue: '2'
keyword:
- Applied Mathematics
- Computational Mathematics
- Control and Optimization
- Management Science and Operations Research
- Computer Networks and Communications
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://academic.oup.com/comnet/article-pdf/12/2/cnae009/56832119/cnae009.pdf
oa: '1'
publication: Journal of Complex Networks
publication_identifier:
  issn:
  - 2051-1329
publication_status: published
publisher: Oxford University Press (OUP)
status: public
title: Heteroclinic dynamics in network dynamical systems with higher-order interactions
type: journal_article
user_id: '97359'
volume: 12
year: '2024'
...
---
_id: '32447'
abstract:
- lang: eng
  text: 'We present a new gradient-like dynamical system related to unconstrained
    convex smooth multiobjective optimization which involves inertial effects and
    asymptotic vanishing damping. To the best of our knowledge, this system is the
    first inertial gradient-like system for multiobjective optimization problems including
    asymptotic vanishing damping, expanding the ideas previously laid out in [H. Attouch
    and G. Garrigos, Multiobjective Optimization: An Inertial Dynamical Approach to
    Pareto Optima, preprint, arXiv:1506.02823, 2015]. We prove existence of solutions
    to this system in finite dimensions and further prove that its bounded solutions
    converge weakly to weakly Pareto optimal points. In addition, we obtain a convergence
    rate of order \(\mathcal{O}(t^{-2})\) for the function values measured with a
    merit function. This approach presents a good basis for the development of fast
    gradient methods for multiobjective optimization.'
article_type: original
author:
- first_name: Konstantin
  full_name: Sonntag, Konstantin
  id: '56399'
  last_name: Sonntag
  orcid: https://orcid.org/0000-0003-3384-3496
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Sonntag K, Peitz S. Fast Convergence of Inertial Multiobjective Gradient-Like
    Systems with Asymptotic Vanishing Damping. <i>SIAM Journal on Optimization</i>.
    2024;34(3):2259-2286. doi:<a href="https://doi.org/10.1137/23M1588512">10.1137/23M1588512</a>
  apa: Sonntag, K., &#38; Peitz, S. (2024). Fast Convergence of Inertial Multiobjective
    Gradient-Like Systems with Asymptotic Vanishing Damping. <i>SIAM Journal on Optimization</i>,
    <i>34</i>(3), 2259–2286. <a href="https://doi.org/10.1137/23M1588512">https://doi.org/10.1137/23M1588512</a>
  bibtex: '@article{Sonntag_Peitz_2024, title={Fast Convergence of Inertial Multiobjective
    Gradient-Like Systems with Asymptotic Vanishing Damping}, volume={34}, DOI={<a
    href="https://doi.org/10.1137/23M1588512">10.1137/23M1588512</a>}, number={3},
    journal={SIAM Journal on Optimization}, publisher={Society for Industrial and
    Applied Mathematics}, author={Sonntag, Konstantin and Peitz, Sebastian}, year={2024},
    pages={2259–2286} }'
  chicago: 'Sonntag, Konstantin, and Sebastian Peitz. “Fast Convergence of Inertial
    Multiobjective Gradient-Like Systems with Asymptotic Vanishing Damping.” <i>SIAM
    Journal on Optimization</i> 34, no. 3 (2024): 2259–86. <a href="https://doi.org/10.1137/23M1588512">https://doi.org/10.1137/23M1588512</a>.'
  ieee: 'K. Sonntag and S. Peitz, “Fast Convergence of Inertial Multiobjective Gradient-Like
    Systems with Asymptotic Vanishing Damping,” <i>SIAM Journal on Optimization</i>,
    vol. 34, no. 3, pp. 2259–2286, 2024, doi: <a href="https://doi.org/10.1137/23M1588512">10.1137/23M1588512</a>.'
  mla: Sonntag, Konstantin, and Sebastian Peitz. “Fast Convergence of Inertial Multiobjective
    Gradient-Like Systems with Asymptotic Vanishing Damping.” <i>SIAM Journal on Optimization</i>,
    vol. 34, no. 3, Society for Industrial and Applied Mathematics, 2024, pp. 2259–86,
    doi:<a href="https://doi.org/10.1137/23M1588512">10.1137/23M1588512</a>.
  short: K. Sonntag, S. Peitz, SIAM Journal on Optimization 34 (2024) 2259–2286.
date_created: 2022-07-28T11:53:02Z
date_updated: 2024-07-02T09:27:39Z
department:
- _id: '101'
- _id: '655'
doi: 10.1137/23M1588512
intvolume: '        34'
issue: '3'
keyword:
- multiobjective optimization
- Pareto optimization
- Lyapunov analysis
- gradient-likedynamical systems
- inertial dynamics
- asymptotic vanishing damping
- fast convergence
language:
- iso: eng
page: 2259 - 2286
publication: SIAM Journal on Optimization
publication_identifier:
  issn:
  - 1095-7189
publication_status: published
publisher: Society for Industrial and Applied Mathematics
status: public
title: Fast Convergence of Inertial Multiobjective Gradient-Like Systems with Asymptotic
  Vanishing Damping
type: journal_article
user_id: '56399'
volume: 34
year: '2024'
...
---
_id: '59171'
abstract:
- lang: eng
  text: To model dynamical systems on networks with higher-order (non-pairwise) interactions,
    we recently introduced a new class of ordinary differential equations (ODEs) on
    hypernetworks. Here, we consider one-parameter synchrony breaking bifurcations
    in such ODEs. We call a synchrony breaking steady-state branch ‘reluctant’ if
    it is tangent to a synchrony space, but does not lie inside it. We prove that
    reluctant synchrony breaking is ubiquitous in hypernetwork systems, by constructing
    a large class of examples that support it. We also give an explicit formula for
    the order of tangency to the synchrony space of a reluctant steady-state branch.
author:
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
- first_name: Eddie
  full_name: Nijholt, Eddie
  last_name: Nijholt
- first_name: Bob
  full_name: Rink, Bob
  last_name: Rink
citation:
  ama: 'von der Gracht S, Nijholt E, Rink B. Higher-order interactions lead to ‘reluctant’
    synchrony breaking. <i>Proceedings of the Royal Society A: Mathematical, Physical
    and Engineering Sciences</i>. 2024;480(2301). doi:<a href="https://doi.org/10.1098/rspa.2023.0945">10.1098/rspa.2023.0945</a>'
  apa: 'von der Gracht, S., Nijholt, E., &#38; Rink, B. (2024). Higher-order interactions
    lead to ‘reluctant’ synchrony breaking. <i>Proceedings of the Royal Society A:
    Mathematical, Physical and Engineering Sciences</i>, <i>480</i>(2301). <a href="https://doi.org/10.1098/rspa.2023.0945">https://doi.org/10.1098/rspa.2023.0945</a>'
  bibtex: '@article{von der Gracht_Nijholt_Rink_2024, title={Higher-order interactions
    lead to ‘reluctant’ synchrony breaking}, volume={480}, DOI={<a href="https://doi.org/10.1098/rspa.2023.0945">10.1098/rspa.2023.0945</a>},
    number={2301}, journal={Proceedings of the Royal Society A: Mathematical, Physical
    and Engineering Sciences}, publisher={The Royal Society}, author={von der Gracht,
    Sören and Nijholt, Eddie and Rink, Bob}, year={2024} }'
  chicago: 'Gracht, Sören von der, Eddie Nijholt, and Bob Rink. “Higher-Order Interactions
    Lead to ‘Reluctant’ Synchrony Breaking.” <i>Proceedings of the Royal Society A:
    Mathematical, Physical and Engineering Sciences</i> 480, no. 2301 (2024). <a href="https://doi.org/10.1098/rspa.2023.0945">https://doi.org/10.1098/rspa.2023.0945</a>.'
  ieee: 'S. von der Gracht, E. Nijholt, and B. Rink, “Higher-order interactions lead
    to ‘reluctant’ synchrony breaking,” <i>Proceedings of the Royal Society A: Mathematical,
    Physical and Engineering Sciences</i>, vol. 480, no. 2301, 2024, doi: <a href="https://doi.org/10.1098/rspa.2023.0945">10.1098/rspa.2023.0945</a>.'
  mla: 'von der Gracht, Sören, et al. “Higher-Order Interactions Lead to ‘Reluctant’
    Synchrony Breaking.” <i>Proceedings of the Royal Society A: Mathematical, Physical
    and Engineering Sciences</i>, vol. 480, no. 2301, The Royal Society, 2024, doi:<a
    href="https://doi.org/10.1098/rspa.2023.0945">10.1098/rspa.2023.0945</a>.'
  short: 'S. von der Gracht, E. Nijholt, B. Rink, Proceedings of the Royal Society
    A: Mathematical, Physical and Engineering Sciences 480 (2024).'
date_created: 2025-03-27T10:15:06Z
date_updated: 2025-03-27T10:19:56Z
ddc:
- '510'
department:
- _id: '101'
doi: 10.1098/rspa.2023.0945
file:
- access_level: open_access
  content_type: application/pdf
  creator: svdg
  date_created: 2025-03-27T10:16:20Z
  date_updated: 2025-03-27T10:19:48Z
  file_id: '59172'
  file_name: higher-order-interactions-lead-to-reluctant-synchrony-breaking.pdf
  file_size: 820435
  relation: main_file
file_date_updated: 2025-03-27T10:19:48Z
has_accepted_license: '1'
intvolume: '       480'
issue: '2301'
keyword:
- higher-order interactions
- synchrony breaking
- network dynamics
- coupled cell systems
language:
- iso: eng
oa: '1'
publication: 'Proceedings of the Royal Society A: Mathematical, Physical and Engineering
  Sciences'
publication_identifier:
  issn:
  - 1364-5021
  - 1471-2946
publication_status: published
publisher: The Royal Society
status: public
title: Higher-order interactions lead to ‘reluctant’ synchrony breaking
type: journal_article
user_id: '97359'
volume: 480
year: '2024'
...
---
_id: '21199'
abstract:
- lang: eng
  text: "As in almost every other branch of science, the major advances in data\r\nscience
    and machine learning have also resulted in significant improvements\r\nregarding
    the modeling and simulation of nonlinear dynamical systems. It is\r\nnowadays
    possible to make accurate medium to long-term predictions of highly\r\ncomplex
    systems such as the weather, the dynamics within a nuclear fusion\r\nreactor,
    of disease models or the stock market in a very efficient manner. In\r\nmany cases,
    predictive methods are advertised to ultimately be useful for\r\ncontrol, as the
    control of high-dimensional nonlinear systems is an engineering\r\ngrand challenge
    with huge potential in areas such as clean and efficient energy\r\nproduction,
    or the development of advanced medical devices. However, the\r\nquestion of how
    to use a predictive model for control is often left unanswered\r\ndue to the associated
    challenges, namely a significantly higher system\r\ncomplexity, the requirement
    of much larger data sets and an increased and often\r\nproblem-specific modeling
    effort. To solve these issues, we present a universal\r\nframework (which we call
    QuaSiModO:\r\nQuantization-Simulation-Modeling-Optimization) to transform arbitrary\r\npredictive
    models into control systems and use them for feedback control. The\r\nadvantages
    of our approach are a linear increase in data requirements with\r\nrespect to
    the control dimension, performance guarantees that rely exclusively\r\non the
    accuracy of the predictive model, and only little prior knowledge\r\nrequirements
    in control theory to solve complex control problems. In particular\r\nthe latter
    point is of key importance to enable a large number of researchers\r\nand practitioners
    to exploit the ever increasing capabilities of predictive\r\nmodels for control
    in a straight-forward and systematic fashion."
article_number: '110840'
author:
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Katharina
  full_name: Bieker, Katharina
  id: '32829'
  last_name: Bieker
citation:
  ama: Peitz S, Bieker K. On the Universal Transformation of Data-Driven Models to
    Control Systems. <i>Automatica</i>. 2023;149. doi:<a href="https://doi.org/10.1016/j.automatica.2022.110840">10.1016/j.automatica.2022.110840</a>
  apa: Peitz, S., &#38; Bieker, K. (2023). On the Universal Transformation of Data-Driven
    Models to Control Systems. <i>Automatica</i>, <i>149</i>, Article 110840. <a href="https://doi.org/10.1016/j.automatica.2022.110840">https://doi.org/10.1016/j.automatica.2022.110840</a>
  bibtex: '@article{Peitz_Bieker_2023, title={On the Universal Transformation of Data-Driven
    Models to Control Systems}, volume={149}, DOI={<a href="https://doi.org/10.1016/j.automatica.2022.110840">10.1016/j.automatica.2022.110840</a>},
    number={110840}, journal={Automatica}, publisher={Elsevier}, author={Peitz, Sebastian
    and Bieker, Katharina}, year={2023} }'
  chicago: Peitz, Sebastian, and Katharina Bieker. “On the Universal Transformation
    of Data-Driven Models to Control Systems.” <i>Automatica</i> 149 (2023). <a href="https://doi.org/10.1016/j.automatica.2022.110840">https://doi.org/10.1016/j.automatica.2022.110840</a>.
  ieee: 'S. Peitz and K. Bieker, “On the Universal Transformation of Data-Driven Models
    to Control Systems,” <i>Automatica</i>, vol. 149, Art. no. 110840, 2023, doi:
    <a href="https://doi.org/10.1016/j.automatica.2022.110840">10.1016/j.automatica.2022.110840</a>.'
  mla: Peitz, Sebastian, and Katharina Bieker. “On the Universal Transformation of
    Data-Driven Models to Control Systems.” <i>Automatica</i>, vol. 149, 110840, Elsevier,
    2023, doi:<a href="https://doi.org/10.1016/j.automatica.2022.110840">10.1016/j.automatica.2022.110840</a>.
  short: S. Peitz, K. Bieker, Automatica 149 (2023).
date_created: 2021-02-10T07:04:15Z
date_updated: 2023-01-07T12:01:58Z
department:
- _id: '101'
- _id: '655'
doi: 10.1016/j.automatica.2022.110840
intvolume: '       149'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://www.sciencedirect.com/science/article/pii/S0005109822007075/pdfft?isDTMRedir=true&download=true
oa: '1'
project:
- _id: '52'
  name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication: Automatica
publication_status: published
publisher: Elsevier
status: public
title: On the Universal Transformation of Data-Driven Models to Control Systems
type: journal_article
user_id: '47427'
volume: 149
year: '2023'
...
---
_id: '49326'
abstract:
- lang: eng
  text: Many networked systems are governed by non-pairwise interactions between nodes.
    The resulting higher-order interaction structure can then be encoded by means
    of a hypernetwork. In this paper we consider dynamical systems on hypernetworks
    by defining a class of admissible maps for every such hypernetwork. We explain
    how to classify robust cluster synchronization patterns on hypernetworks by finding
    balanced partitions, and we generalize the concept of a graph fibration to the
    hypernetwork context. We also show that robust synchronization patterns are only
    fully determined by polynomial admissible maps of high order. This means that,
    unlike in dyadic networks, cluster synchronization on hypernetworks is a higher-order,
    i.e., nonlinear, effect. We give a formula, in terms of the order of the hypernetwork,
    for the degree of the polynomial admissible maps that determine robust synchronization
    patterns. We also demonstrate that this degree is optimal by investigating a class
    of examples. We conclude by demonstrating how this effect may cause remarkable
    synchrony breaking bifurcations that occur at high polynomial degree.
author:
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
- first_name: Eddie
  full_name: Nijholt, Eddie
  last_name: Nijholt
- first_name: Bob
  full_name: Rink, Bob
  last_name: Rink
citation:
  ama: 'von der Gracht S, Nijholt E, Rink B. Hypernetworks: Cluster Synchronization
    Is a Higher-Order Effect. <i>SIAM Journal on Applied Mathematics</i>. 2023;83(6):2329-2353.
    doi:<a href="https://doi.org/10.1137/23m1561075">10.1137/23m1561075</a>'
  apa: 'von der Gracht, S., Nijholt, E., &#38; Rink, B. (2023). Hypernetworks: Cluster
    Synchronization Is a Higher-Order Effect. <i>SIAM Journal on Applied Mathematics</i>,
    <i>83</i>(6), 2329–2353. <a href="https://doi.org/10.1137/23m1561075">https://doi.org/10.1137/23m1561075</a>'
  bibtex: '@article{von der Gracht_Nijholt_Rink_2023, title={Hypernetworks: Cluster
    Synchronization Is a Higher-Order Effect}, volume={83}, DOI={<a href="https://doi.org/10.1137/23m1561075">10.1137/23m1561075</a>},
    number={6}, journal={SIAM Journal on Applied Mathematics}, publisher={Society
    for Industrial &#38; Applied Mathematics (SIAM)}, author={von der Gracht, Sören
    and Nijholt, Eddie and Rink, Bob}, year={2023}, pages={2329–2353} }'
  chicago: 'Gracht, Sören von der, Eddie Nijholt, and Bob Rink. “Hypernetworks: Cluster
    Synchronization Is a Higher-Order Effect.” <i>SIAM Journal on Applied Mathematics</i>
    83, no. 6 (2023): 2329–53. <a href="https://doi.org/10.1137/23m1561075">https://doi.org/10.1137/23m1561075</a>.'
  ieee: 'S. von der Gracht, E. Nijholt, and B. Rink, “Hypernetworks: Cluster Synchronization
    Is a Higher-Order Effect,” <i>SIAM Journal on Applied Mathematics</i>, vol. 83,
    no. 6, pp. 2329–2353, 2023, doi: <a href="https://doi.org/10.1137/23m1561075">10.1137/23m1561075</a>.'
  mla: 'von der Gracht, Sören, et al. “Hypernetworks: Cluster Synchronization Is a
    Higher-Order Effect.” <i>SIAM Journal on Applied Mathematics</i>, vol. 83, no.
    6, Society for Industrial &#38; Applied Mathematics (SIAM), 2023, pp. 2329–53,
    doi:<a href="https://doi.org/10.1137/23m1561075">10.1137/23m1561075</a>.'
  short: S. von der Gracht, E. Nijholt, B. Rink, SIAM Journal on Applied Mathematics
    83 (2023) 2329–2353.
date_created: 2023-11-29T10:50:05Z
date_updated: 2023-11-29T10:52:23Z
department:
- _id: '101'
doi: 10.1137/23m1561075
external_id:
  arxiv:
  - '2302.08974'
intvolume: '        83'
issue: '6'
keyword:
- Applied Mathematics
language:
- iso: eng
page: 2329-2353
publication: SIAM Journal on Applied Mathematics
publication_identifier:
  issn:
  - 0036-1399
  - 1095-712X
publication_status: published
publisher: Society for Industrial & Applied Mathematics (SIAM)
status: public
title: 'Hypernetworks: Cluster Synchronization Is a Higher-Order Effect'
type: journal_article
user_id: '97359'
volume: 83
year: '2023'
...
---
_id: '46578'
abstract:
- lang: eng
  text: 'Multiobjective optimization plays an increasingly important role in modern
    applications, where several criteria are often of equal importance. The task in
    multiobjective optimization and multiobjective optimal control is therefore to
    compute the set of optimal compromises (the Pareto set) between the conflicting
    objectives. The advances in algorithms and the increasing interest in Pareto-optimal
    solutions have led to a wide range of new applications related to optimal and
    feedback control - potentially with non-smoothness both on the level of the objectives
    or in the system dynamics. This results in new challenges such as dealing with
    expensive models (e.g., governed by partial differential equations (PDEs)) and
    developing dedicated algorithms handling the non-smoothness. Since in contrast
    to single-objective optimization, the Pareto set generally consists of an infinite
    number of solutions, the computational effort can quickly become challenging,
    which is particularly problematic when the objectives are costly to evaluate or
    when a solution has to be presented very quickly. This article gives an overview
    of recent developments in the field of multiobjective optimization of non-smooth
    PDE-constrained problems. In particular we report on the advances achieved within
    Project 2 "Multiobjective Optimization of Non-Smooth PDE-Constrained Problems
    - Switches, State Constraints and Model Order Reduction" of the DFG Priority Programm
    1962 "Non-smooth and Complementarity-based Distributed Parameter Systems: Simulation
    and Hierarchical Optimization".'
author:
- first_name: Marco
  full_name: Bernreuther, Marco
  last_name: Bernreuther
- first_name: Michael
  full_name: Dellnitz, Michael
  last_name: Dellnitz
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Georg
  full_name: Müller, Georg
  last_name: Müller
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Konstantin
  full_name: Sonntag, Konstantin
  id: '56399'
  last_name: Sonntag
  orcid: https://orcid.org/0000-0003-3384-3496
- first_name: Stefan
  full_name: Volkwein, Stefan
  last_name: Volkwein
citation:
  ama: Bernreuther M, Dellnitz M, Gebken B, et al. Multiobjective Optimization of
    Non-Smooth PDE-Constrained Problems. <i>arXiv:230801113</i>. Published online
    2023.
  apa: Bernreuther, M., Dellnitz, M., Gebken, B., Müller, G., Peitz, S., Sonntag,
    K., &#38; Volkwein, S. (2023). Multiobjective Optimization of Non-Smooth PDE-Constrained
    Problems. In <i>arXiv:2308.01113</i>.
  bibtex: '@article{Bernreuther_Dellnitz_Gebken_Müller_Peitz_Sonntag_Volkwein_2023,
    title={Multiobjective Optimization of Non-Smooth PDE-Constrained Problems}, journal={arXiv:2308.01113},
    author={Bernreuther, Marco and Dellnitz, Michael and Gebken, Bennet and Müller,
    Georg and Peitz, Sebastian and Sonntag, Konstantin and Volkwein, Stefan}, year={2023}
    }'
  chicago: Bernreuther, Marco, Michael Dellnitz, Bennet Gebken, Georg Müller, Sebastian
    Peitz, Konstantin Sonntag, and Stefan Volkwein. “Multiobjective Optimization of
    Non-Smooth PDE-Constrained Problems.” <i>ArXiv:2308.01113</i>, 2023.
  ieee: M. Bernreuther <i>et al.</i>, “Multiobjective Optimization of Non-Smooth PDE-Constrained
    Problems,” <i>arXiv:2308.01113</i>. 2023.
  mla: Bernreuther, Marco, et al. “Multiobjective Optimization of Non-Smooth PDE-Constrained
    Problems.” <i>ArXiv:2308.01113</i>, 2023.
  short: M. Bernreuther, M. Dellnitz, B. Gebken, G. Müller, S. Peitz, K. Sonntag,
    S. Volkwein, ArXiv:2308.01113 (2023).
date_created: 2023-08-21T05:50:12Z
date_updated: 2024-02-21T12:22:20Z
department:
- _id: '655'
- _id: '101'
external_id:
  arxiv:
  - '2308.01113'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/pdf/2308.01113
oa: '1'
publication: arXiv:2308.01113
status: public
title: Multiobjective Optimization of Non-Smooth PDE-Constrained Problems
type: preprint
user_id: '47427'
year: '2023'
...
---
_id: '27426'
abstract:
- lang: eng
  text: "Regularization is used in many different areas of optimization when solutions\r\nare
    sought which not only minimize a given function, but also possess a certain\r\ndegree
    of regularity. Popular applications are image denoising, sparse\r\nregression
    and machine learning. Since the choice of the regularization\r\nparameter is crucial
    but often difficult, path-following methods are used to\r\napproximate the entire
    regularization path, i.e., the set of all possible\r\nsolutions for all regularization
    parameters. Due to their nature, the\r\ndevelopment of these methods requires
    structural results about the\r\nregularization path. The goal of this article
    is to derive these results for\r\nthe case of a smooth objective function which
    is penalized by a piecewise\r\ndifferentiable regularization term. We do this
    by treating regularization as a\r\nmultiobjective optimization problem. Our results
    suggest that even in this\r\ngeneral case, the regularization path is piecewise
    smooth. Moreover, our theory\r\nallows for a classification of the nonsmooth features
    that occur in between\r\nsmooth parts. This is demonstrated in two applications,
    namely support-vector\r\nmachines and exact penalty methods."
author:
- first_name: Bennet
  full_name: Gebken, Bennet
  id: '32643'
  last_name: Gebken
- first_name: Katharina
  full_name: Bieker, Katharina
  id: '32829'
  last_name: Bieker
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
citation:
  ama: Gebken B, Bieker K, Peitz S. On the structure of regularization paths for piecewise
    differentiable regularization terms. <i>Journal of Global Optimization</i>. 2023;85(3):709-741.
    doi:<a href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>
  apa: Gebken, B., Bieker, K., &#38; Peitz, S. (2023). On the structure of regularization
    paths for piecewise differentiable regularization terms. <i>Journal of Global
    Optimization</i>, <i>85</i>(3), 709–741. <a href="https://doi.org/10.1007/s10898-022-01223-2">https://doi.org/10.1007/s10898-022-01223-2</a>
  bibtex: '@article{Gebken_Bieker_Peitz_2023, title={On the structure of regularization
    paths for piecewise differentiable regularization terms}, volume={85}, DOI={<a
    href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>},
    number={3}, journal={Journal of Global Optimization}, author={Gebken, Bennet and
    Bieker, Katharina and Peitz, Sebastian}, year={2023}, pages={709–741} }'
  chicago: 'Gebken, Bennet, Katharina Bieker, and Sebastian Peitz. “On the Structure
    of Regularization Paths for Piecewise Differentiable Regularization Terms.” <i>Journal
    of Global Optimization</i> 85, no. 3 (2023): 709–41. <a href="https://doi.org/10.1007/s10898-022-01223-2">https://doi.org/10.1007/s10898-022-01223-2</a>.'
  ieee: 'B. Gebken, K. Bieker, and S. Peitz, “On the structure of regularization paths
    for piecewise differentiable regularization terms,” <i>Journal of Global Optimization</i>,
    vol. 85, no. 3, pp. 709–741, 2023, doi: <a href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>.'
  mla: Gebken, Bennet, et al. “On the Structure of Regularization Paths for Piecewise
    Differentiable Regularization Terms.” <i>Journal of Global Optimization</i>, vol.
    85, no. 3, 2023, pp. 709–41, doi:<a href="https://doi.org/10.1007/s10898-022-01223-2">10.1007/s10898-022-01223-2</a>.
  short: B. Gebken, K. Bieker, S. Peitz, Journal of Global Optimization 85 (2023)
    709–741.
date_created: 2021-11-15T09:24:59Z
date_updated: 2023-03-11T17:16:33Z
department:
- _id: '101'
- _id: '655'
doi: 10.1007/s10898-022-01223-2
intvolume: '        85'
issue: '3'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://link.springer.com/content/pdf/10.1007/s10898-022-01223-2.pdf
oa: '1'
page: 709-741
publication: Journal of Global Optimization
status: public
title: On the structure of regularization paths for piecewise differentiable regularization
  terms
type: journal_article
user_id: '47427'
volume: 85
year: '2023'
...
---
_id: '45498'
abstract:
- lang: eng
  text: "We present a novel method for high-order phase reduction in networks of\r\nweakly
    coupled oscillators and, more generally, perturbations of reducible\r\nnormally
    hyperbolic (quasi-)periodic tori. Our method works by computing an\r\nasymptotic
    expansion for an embedding of the perturbed invariant torus, as well\r\nas for
    the reduced phase dynamics in local coordinates. Both can be determined\r\nto
    arbitrary degrees of accuracy, and we show that the phase dynamics may\r\ndirectly
    be obtained in normal form. We apply the method to predict remote\r\nsynchronisation
    in a chain of coupled Stuart-Landau oscillators."
author:
- first_name: Sören
  full_name: von der Gracht, Sören
  id: '97359'
  last_name: von der Gracht
  orcid: 0000-0002-8054-2058
- first_name: Eddie
  full_name: Nijholt, Eddie
  last_name: Nijholt
- first_name: Bob
  full_name: Rink, Bob
  last_name: Rink
citation:
  ama: von der Gracht S, Nijholt E, Rink B. A parametrisation method for high-order
    phase reduction in coupled  oscillator networks. <i>arXiv:230603320</i>.
  apa: von der Gracht, S., Nijholt, E., &#38; Rink, B. (n.d.). A parametrisation method
    for high-order phase reduction in coupled  oscillator networks. In <i>arXiv:2306.03320</i>.
  bibtex: '@article{von der Gracht_Nijholt_Rink, title={A parametrisation method for
    high-order phase reduction in coupled  oscillator networks}, journal={arXiv:2306.03320},
    author={von der Gracht, Sören and Nijholt, Eddie and Rink, Bob} }'
  chicago: Gracht, Sören von der, Eddie Nijholt, and Bob Rink. “A Parametrisation
    Method for High-Order Phase Reduction in Coupled  Oscillator Networks.” <i>ArXiv:2306.03320</i>,
    n.d.
  ieee: S. von der Gracht, E. Nijholt, and B. Rink, “A parametrisation method for
    high-order phase reduction in coupled  oscillator networks,” <i>arXiv:2306.03320</i>.
    .
  mla: von der Gracht, Sören, et al. “A Parametrisation Method for High-Order Phase
    Reduction in Coupled  Oscillator Networks.” <i>ArXiv:2306.03320</i>.
  short: S. von der Gracht, E. Nijholt, B. Rink, ArXiv:2306.03320 (n.d.).
date_created: 2023-06-07T07:57:28Z
date_updated: 2023-06-07T07:59:06Z
department:
- _id: '101'
external_id:
  arxiv:
  - '2306.03320'
language:
- iso: eng
main_file_link:
- url: https://arxiv.org/pdf/2306.03320
page: '29'
publication: arXiv:2306.03320
publication_status: submitted
status: public
title: A parametrisation method for high-order phase reduction in coupled  oscillator
  networks
type: preprint
user_id: '97359'
year: '2023'
...
---
_id: '23428'
abstract:
- lang: eng
  text: "The Koopman operator has become an essential tool for data-driven approximation
    of dynamical (control) systems in recent years, e.g., via extended dynamic mode
    decomposition. Despite its popularity, convergence results and, in particular,
    error bounds are still quite scarce. In this paper, we derive probabilistic bounds
    for the approximation error and the prediction error depending on the number of
    training data points; for both ordinary and stochastic differential equations.
    Moreover, we extend our analysis to nonlinear control-affine systems using either
    ergodic trajectories or i.i.d.\r\nsamples. Here, we exploit the linearity of the
    Koopman generator to obtain a bilinear system and, thus, circumvent the curse
    of dimensionality since we do not autonomize the system by augmenting the state
    by the control inputs. To the\r\nbest of our knowledge, this is the first finite-data
    error analysis in the stochastic and/or control setting. Finally, we demonstrate
    the effectiveness of the proposed approach by comparing it with state-of-the-art
    techniques showing its superiority whenever state and control are coupled."
article_number: '14'
author:
- first_name: Feliks
  full_name: Nüske, Feliks
  id: '81513'
  last_name: Nüske
  orcid: 0000-0003-2444-7889
- first_name: Sebastian
  full_name: Peitz, Sebastian
  id: '47427'
  last_name: Peitz
  orcid: 0000-0002-3389-793X
- first_name: Friedrich
  full_name: Philipp, Friedrich
  last_name: Philipp
- first_name: Manuel
  full_name: Schaller, Manuel
  last_name: Schaller
- first_name: Karl
  full_name: Worthmann, Karl
  last_name: Worthmann
citation:
  ama: Nüske F, Peitz S, Philipp F, Schaller M, Worthmann K. Finite-data error bounds
    for Koopman-based prediction and control. <i>Journal of Nonlinear Science</i>.
    2023;33. doi:<a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>
  apa: Nüske, F., Peitz, S., Philipp, F., Schaller, M., &#38; Worthmann, K. (2023).
    Finite-data error bounds for Koopman-based prediction and control. <i>Journal
    of Nonlinear Science</i>, <i>33</i>, Article 14. <a href="https://doi.org/10.1007/s00332-022-09862-1">https://doi.org/10.1007/s00332-022-09862-1</a>
  bibtex: '@article{Nüske_Peitz_Philipp_Schaller_Worthmann_2023, title={Finite-data
    error bounds for Koopman-based prediction and control}, volume={33}, DOI={<a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>},
    number={14}, journal={Journal of Nonlinear Science}, author={Nüske, Feliks and
    Peitz, Sebastian and Philipp, Friedrich and Schaller, Manuel and Worthmann, Karl},
    year={2023} }'
  chicago: Nüske, Feliks, Sebastian Peitz, Friedrich Philipp, Manuel Schaller, and
    Karl Worthmann. “Finite-Data Error Bounds for Koopman-Based Prediction and Control.”
    <i>Journal of Nonlinear Science</i> 33 (2023). <a href="https://doi.org/10.1007/s00332-022-09862-1">https://doi.org/10.1007/s00332-022-09862-1</a>.
  ieee: 'F. Nüske, S. Peitz, F. Philipp, M. Schaller, and K. Worthmann, “Finite-data
    error bounds for Koopman-based prediction and control,” <i>Journal of Nonlinear
    Science</i>, vol. 33, Art. no. 14, 2023, doi: <a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>.'
  mla: Nüske, Feliks, et al. “Finite-Data Error Bounds for Koopman-Based Prediction
    and Control.” <i>Journal of Nonlinear Science</i>, vol. 33, 14, 2023, doi:<a href="https://doi.org/10.1007/s00332-022-09862-1">10.1007/s00332-022-09862-1</a>.
  short: F. Nüske, S. Peitz, F. Philipp, M. Schaller, K. Worthmann, Journal of Nonlinear
    Science 33 (2023).
date_created: 2021-08-17T12:25:09Z
date_updated: 2023-08-24T07:50:12Z
department:
- _id: '101'
- _id: '655'
doi: 10.1007/s00332-022-09862-1
intvolume: '        33'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://link.springer.com/content/pdf/10.1007/s00332-022-09862-1.pdf
oa: '1'
publication: Journal of Nonlinear Science
publication_status: published
status: public
title: Finite-data error bounds for Koopman-based prediction and control
type: journal_article
user_id: '47427'
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'
...
