---
OA_place: publisher
_id: '18979'
abstract:
- lang: eng
text: "Topological Data Analysis (TDA) is a discipline utilizing the mathematical
field of topology to study data, most prominently collections of point sets. This
thesis summarizes three projects related to computations in TDA.\r\n\r\nThe first
one establishes a variant of TDA for chromatic point sets, where each point is
given a color. For example, we are given positions of cells within a tumor microenvironment,
and color the cancerous cells red, and the immune cells blue.\r\n\r\nThe aim is
then to give a quantitative description of how the two or more sets of points
spatially interact. Building on image, kernel and cokernel variants of persistent
homology, we suggest six-packs of persistent diagrams as such a descriptor.\r\n\r\nWe
describe a construction of a chromatic alpha complex, which enables efficient
computation of several variants of the six-packs. We give topological descriptions
of natural subcomplexes of the chromatic alpha complex, and show that the radii
of the simplices form a discrete Morse function. Finally, we provide an implementation
of the presented chromatic TDA pipeline.\r\n\r\nThe second part aims to translate
a powerful tool of sheaf theory to elementary terms using labeled matrices. The
goal is to enable their use in computational settings. We show that derived categories
of sheaves over finite posets have, up to isomorphism, unique objects---minimal
injective resolutions---and give a concrete algorithm to compute them. We further
describe simple algorithms to compute derived pushforwards and pullbacks for monotonic
maps, and their proper variants for inclusions, and demonstrate their tractability
by providing an implementation. Finally, we suggest a discrete definition of microsupport
and show desirable properties inspired by discrete Morse theory.\r\n\r\nIn the
last part, we present a collection of observations about collapses. We give a
characterization of collapsibility in terms of unitriangular submatrices of the
boundary matrix, a cotree-tree decomposition, and the optimal solution to a variant
of the Procrustes problem. We establish relation between dual collapses and relative
Morse theory and pose several open questions. Finally, focusing on complexes embedded
in the three-dimensional Euclidean space, we describe a relation between the collapsibility
and the triviality of a polygonal knot."
acknowledgement: "The research presented in this thesis was funded with the Wittgenstein
Prize,\r\nAustrian Science Fund (FWF), grant no. Z 342-N31, and from the DFG Collaborative
Research\r\nCenter TRR 109, ‘Discretization in Geometry and Dynamics’, Austrian
Science Fund (FWF),\r\ngrant no. I 02979-N35.\r\n"
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Ondrej
full_name: Draganov, Ondrej
id: 2B23F01E-F248-11E8-B48F-1D18A9856A87
last_name: Draganov
orcid: 0000-0003-0464-3823
citation:
ama: Draganov O. Structures and computations in topological data analysis. 2025.
doi:10.15479/at:ista:18979
apa: Draganov, O. (2025). Structures and computations in topological data analysis.
Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:18979
chicago: Draganov, Ondrej. “Structures and Computations in Topological Data Analysis.”
Institute of Science and Technology Austria, 2025. https://doi.org/10.15479/at:ista:18979.
ieee: O. Draganov, “Structures and computations in topological data analysis,” Institute
of Science and Technology Austria, 2025.
ista: Draganov O. 2025. Structures and computations in topological data analysis.
Institute of Science and Technology Austria.
mla: Draganov, Ondrej. Structures and Computations in Topological Data Analysis.
Institute of Science and Technology Austria, 2025, doi:10.15479/at:ista:18979.
short: O. Draganov, Structures and Computations in Topological Data Analysis, Institute
of Science and Technology Austria, 2025.
corr_author: '1'
date_created: 2025-01-31T17:04:40Z
date_published: 2025-02-03T00:00:00Z
date_updated: 2026-04-07T11:47:30Z
day: '03'
ddc:
- '514'
- '004'
degree_awarded: PhD
department:
- _id: GradSch
- _id: HeEd
doi: 10.15479/at:ista:18979
file:
- access_level: closed
checksum: af6567e5d35e5eb330b8925ae37f1998
content_type: application/zip
creator: odragano
date_created: 2025-01-31T16:58:30Z
date_updated: 2025-01-31T16:58:30Z
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checksum: c3fef68e35b9dc2020b2ca6006da6343
content_type: application/pdf
creator: odragano
date_created: 2025-02-04T16:22:07Z
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file_name: Thesis.pdf
file_size: 8857514
relation: main_file
file_date_updated: 2025-02-04T16:22:07Z
has_accepted_license: '1'
keyword:
- topological data analysis
- chromatic point set
- alpha complex
- persistent homology
- six pack
- sheaf
- microlocal discrete Morse
- injective resolution
- collapse
- knot
- discrete Morse theory
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
page: '140'
project:
- _id: 2561EBF4-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: I02979-N35
name: Persistence and stability of geometric complexes
- _id: 268116B8-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: Z00342
name: Mathematics, Computer Science
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
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- id: '15091'
relation: part_of_dissertation
status: public
- id: '18981'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Herbert
full_name: Edelsbrunner, Herbert
id: 3FB178DA-F248-11E8-B48F-1D18A9856A87
last_name: Edelsbrunner
orcid: 0000-0002-9823-6833
title: Structures and computations in topological data analysis
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...
---
OA_place: publisher
_id: '7460'
abstract:
- lang: eng
text: "Many methods for the reconstruction of shapes from sets of points produce
ordered simplicial complexes, which are collections of vertices, edges, triangles,
and their higher-dimensional analogues, called simplices, in which every simplex
gets assigned a real value measuring its size. This thesis studies ordered simplicial
complexes, with a focus on their topology, which reflects the connectedness of
the represented shapes and the presence of holes. We are interested both in understanding
better the structure of these complexes, as well as in developing algorithms for
applications.\r\n\r\nFor the Delaunay triangulation, the most popular measure
for a simplex is the radius of the smallest empty circumsphere. Based on it, we
revisit Alpha and Wrap complexes and experimentally determine their probabilistic
properties for random data. Also, we prove the existence of tri-partitions, propose
algorithms to open and close holes, and extend the concepts from Euclidean to
Bregman geometries."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Katharina
full_name: Ölsböck, Katharina
id: 4D4AA390-F248-11E8-B48F-1D18A9856A87
last_name: Ölsböck
orcid: 0000-0002-4672-8297
citation:
ama: Ölsböck K. The hole system of triangulated shapes. 2020. doi:10.15479/AT:ISTA:7460
apa: Ölsböck, K. (2020). The hole system of triangulated shapes. Institute
of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:7460
chicago: Ölsböck, Katharina. “The Hole System of Triangulated Shapes.” Institute
of Science and Technology Austria, 2020. https://doi.org/10.15479/AT:ISTA:7460.
ieee: K. Ölsböck, “The hole system of triangulated shapes,” Institute of Science
and Technology Austria, 2020.
ista: Ölsböck K. 2020. The hole system of triangulated shapes. Institute of Science
and Technology Austria.
mla: Ölsböck, Katharina. The Hole System of Triangulated Shapes. Institute
of Science and Technology Austria, 2020, doi:10.15479/AT:ISTA:7460.
short: K. Ölsböck, The Hole System of Triangulated Shapes, Institute of Science
and Technology Austria, 2020.
corr_author: '1'
date_created: 2020-02-06T14:56:53Z
date_published: 2020-02-10T00:00:00Z
date_updated: 2026-04-08T07:23:21Z
day: '10'
ddc:
- '514'
degree_awarded: PhD
department:
- _id: HeEd
- _id: GradSch
doi: 10.15479/AT:ISTA:7460
file:
- access_level: open_access
checksum: 1df9f8c530b443c0e63a3f2e4fde412e
content_type: application/pdf
creator: koelsboe
date_created: 2020-02-06T14:43:54Z
date_updated: 2020-07-14T12:47:58Z
file_id: '7461'
file_name: thesis_ist-final_noack.pdf
file_size: 76195184
relation: main_file
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checksum: 7a52383c812b0be64d3826546509e5a4
content_type: application/x-zip-compressed
creator: koelsboe
date_created: 2020-02-06T14:52:45Z
date_updated: 2020-07-14T12:47:58Z
description: latex source files, figures
file_id: '7462'
file_name: latex-files.zip
file_size: 122103715
relation: source_file
file_date_updated: 2020-07-14T12:47:58Z
has_accepted_license: '1'
keyword:
- shape reconstruction
- hole manipulation
- ordered complexes
- Alpha complex
- Wrap complex
- computational topology
- Bregman geometry
language:
- iso: eng
month: '02'
oa: 1
oa_version: Published Version
page: '155'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '6608'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Herbert
full_name: Edelsbrunner, Herbert
id: 3FB178DA-F248-11E8-B48F-1D18A9856A87
last_name: Edelsbrunner
orcid: 0000-0002-9823-6833
title: The hole system of triangulated shapes
tmp:
image: /images/cc_by_nc_sa.png
legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
BY-NC-SA 4.0)
short: CC BY-NC-SA (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2020'
...