---
_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: '19943'
abstract:
- lang: eng
  text: 'In this paper we continue our study of bifurcations of solutions of boundary-value
    problems for symplectic maps arising as Hamiltonian diffeomorphisms. These have
    been shown to be connected to catastrophe theory via generating functions and
    ordinary and reversal phase space symmetries have been considered. Here we present
    a convenient, coordinate free framework to analyse separated Lagrangian boundary
    value problems which include classical Dirichlet, Neumann and Robin boundary value
    problems. The framework is then used to prove the existence of obstructions arising
    from conformal symplectic symmetries on the bifurcation behaviour of solutions
    to Hamiltonian boundary value problems. Under non-degeneracy conditions, a group
    action by conformal symplectic symmetries has the effect that the flow map cannot
    degenerate in a direction which is tangential to the action. This imposes restrictions
    on which singularities can occur in boundary value problems. Our results generalise
    classical results about conjugate loci on Riemannian manifolds to a large class
    of Hamiltonian boundary value problems with, for example, scaling symmetries. '
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. Hamiltonian boundary value problems, conformal symplectic
    symmetries, and conjugate loci. <i>New Zealand Journal of Mathematics</i>. 2018;48:83-99.
    doi:<a href="https://doi.org/10.53733/34 ">10.53733/34 </a>
  apa: McLachlan, R. I., &#38; Offen, C. (2018). Hamiltonian boundary value problems,
    conformal symplectic symmetries, and conjugate loci. <i>New Zealand Journal of
    Mathematics</i>, <i>48</i>, 83–99. <a href="https://doi.org/10.53733/34 ">https://doi.org/10.53733/34
    </a>
  bibtex: '@article{McLachlan_Offen_2018, title={Hamiltonian boundary value problems,
    conformal symplectic symmetries, and conjugate loci}, volume={48}, DOI={<a href="https://doi.org/10.53733/34
    ">10.53733/34 </a>}, journal={New Zealand Journal of Mathematics}, author={McLachlan,
    Robert I and Offen, Christian}, year={2018}, pages={83–99} }'
  chicago: 'McLachlan, Robert I, and Christian Offen. “Hamiltonian Boundary Value
    Problems, Conformal Symplectic Symmetries, and Conjugate Loci.” <i>New Zealand
    Journal of Mathematics</i> 48 (2018): 83–99. <a href="https://doi.org/10.53733/34
    ">https://doi.org/10.53733/34 </a>.'
  ieee: 'R. I. McLachlan and C. Offen, “Hamiltonian boundary value problems, conformal
    symplectic symmetries, and conjugate loci,” <i>New Zealand Journal of Mathematics</i>,
    vol. 48, pp. 83–99, 2018, doi: <a href="https://doi.org/10.53733/34 ">10.53733/34
    </a>.'
  mla: McLachlan, Robert I., and Christian Offen. “Hamiltonian Boundary Value Problems,
    Conformal Symplectic Symmetries, and Conjugate Loci.” <i>New Zealand Journal of
    Mathematics</i>, vol. 48, 2018, pp. 83–99, doi:<a href="https://doi.org/10.53733/34
    ">10.53733/34 </a>.
  short: R.I. McLachlan, C. Offen, New Zealand Journal of Mathematics 48 (2018) 83–99.
date_created: 2020-10-06T16:39:08Z
date_updated: 2023-09-21T07:29:24Z
ddc:
- '510'
department:
- _id: '636'
doi: '10.53733/34 '
extern: '1'
external_id:
  arxiv:
  - '1804.07479'
file:
- access_level: open_access
  content_type: application/pdf
  creator: coffen
  date_created: 2020-10-06T16:49:29Z
  date_updated: 2020-10-07T14:04:01Z
  file_id: '19946'
  file_name: Hamiltonian_Boundary_Value_Problems,_Conformal_Symplectic_Symmetries,_and_Conjugate_Loci.pdf
  file_size: 3126111
  relation: main_file
  title: Hamiltonian Boundary Value Problems, Conformal Symplectic Symmetries, and
    Conjugate Loci
file_date_updated: 2020-10-07T14:04:01Z
has_accepted_license: '1'
intvolume: '        48'
keyword:
- Hamiltonian boundary value problems
- singularities
- conformal symplectic geometry
- catastrophe theory
- conjugate loci
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://nzjmath.org/index.php/NZJMATH/article/view/34
oa: '1'
page: 83-99
publication: New Zealand Journal of Mathematics
publication_status: published
quality_controlled: '1'
status: public
title: Hamiltonian boundary value problems, conformal symplectic symmetries, and conjugate
  loci
type: journal_article
user_id: '85279'
volume: 48
year: '2018'
...
