License: Creative Commons Attribution 4.0 International license (CC BY 4.0)
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DOI: 10.4230/LIPIcs.SoCG.2022.25
URN: urn:nbn:de:0030-drops-160338
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Chambers, Erin Wolf ; Parsa, Salman ; Schreiber, Hannah

On Complexity of Computing Bottleneck and Lexicographic Optimal Cycles in a Homology Class

LIPIcs-SoCG-2022-25.pdf (1 MB)


Homology features of spaces which appear in applications, for instance 3D meshes, are among the most important topological properties of these objects. Given a non-trivial cycle in a homology class, we consider the problem of computing a representative in that homology class which is optimal. We study two measures of optimality, namely, the lexicographic order of cycles (the lex-optimal cycle) and the bottleneck norm (a bottleneck-optimal cycle). We give a simple algorithm for computing the lex-optimal cycle for a 1-homology class in a closed orientable surface. In contrast to this, our main result is that, in the case of 3-manifolds of size n² in the Euclidean 3-space, the problem of finding a bottleneck optimal cycle cannot be solved more efficiently than solving a system of linear equations with an n × n sparse matrix. From this reduction, we deduce several hardness results. Most notably, we show that for 3-manifolds given as a subset of the 3-space of size n², persistent homology computations are at least as hard as rank computation (for sparse matrices) while ordinary homology computations can be done in O(n² log n) time. This is the first such distinction between these two computations. Moreover, it follows that the same disparity exists between the height persistent homology computation and general sub-level set persistent homology computation for simplicial complexes in the 3-space.

BibTeX - Entry

  author =	{Chambers, Erin Wolf and Parsa, Salman and Schreiber, Hannah},
  title =	{{On Complexity of Computing Bottleneck and Lexicographic Optimal Cycles in a Homology Class}},
  booktitle =	{38th International Symposium on Computational Geometry (SoCG 2022)},
  pages =	{25:1--25:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-227-3},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{224},
  editor =	{Goaoc, Xavier and Kerber, Michael},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{},
  URN =		{urn:nbn:de:0030-drops-160338},
  doi =		{10.4230/LIPIcs.SoCG.2022.25},
  annote =	{Keywords: computational topology, bottleneck optimal cycles, homology}

Keywords: computational topology, bottleneck optimal cycles, homology
Collection: 38th International Symposium on Computational Geometry (SoCG 2022)
Issue Date: 2022
Date of publication: 01.06.2022

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