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Documents authored by Büngener, Aaron

Document
DOI: 10.4230/LIPIcs.GD.2024.27
On k-Planar Graphs Without Short Cycles

Authors: Michael A. Bekos, Prosenjit Bose, Aaron Büngener, Vida Dujmović, Michael Hoffmann, Michael Kaufmann, Pat Morin, Saeed Odak, and Alexandra Weinberger

Published in: LIPIcs, Volume 320, 32nd International Symposium on Graph Drawing and Network Visualization (GD 2024)

Abstract
We study the impact of forbidding short cycles to the edge density of k-planar graphs; a k-planar graph is one that can be drawn in the plane with at most k crossings per edge. Specifically, we consider three settings, according to which the forbidden substructures are 3-cycles, 4-cycles or both of them (i.e., girth ≥ 5). For all three settings and all k ∈ {1,2,3}, we present lower and upper bounds on the maximum number of edges in any k-planar graph on n vertices. Our bounds are of the form c n, for some explicit constant c that depends on k and on the setting. For general k ≥ 4 our bounds are of the form c√kn, for some explicit constant c. These results are obtained by leveraging different techniques, such as the discharging method, the recently introduced density formula for non-planar graphs, and new upper bounds for the crossing number of 2- and 3-planar graphs in combination with corresponding lower bounds based on the Crossing Lemma.
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Michael A. Bekos, Prosenjit Bose, Aaron Büngener, Vida Dujmović, Michael Hoffmann, Michael Kaufmann, Pat Morin, Saeed Odak, and Alexandra Weinberger. On k-Planar Graphs Without Short Cycles. In 32nd International Symposium on Graph Drawing and Network Visualization (GD 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 320, pp. 27:1-27:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{bekos_et_al:LIPIcs.GD.2024.27,
  author =	{Bekos, Michael A. and Bose, Prosenjit and B\"{u}ngener, Aaron and Dujmovi\'{c}, Vida and Hoffmann, Michael and Kaufmann, Michael and Morin, Pat and Odak, Saeed and Weinberger, Alexandra},
  title =	{{On k-Planar Graphs Without Short Cycles}},
  booktitle =	{32nd International Symposium on Graph Drawing and Network Visualization (GD 2024)},
  pages =	{27:1--27:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-343-0},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{320},
  editor =	{Felsner, Stefan and Klein, Karsten},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.GD.2024.27},
  URN =		{urn:nbn:de:0030-drops-213117},
  doi =		{10.4230/LIPIcs.GD.2024.27},
  annote =	{Keywords: Beyond-planar Graphs, k-planar Graphs, Local Crossing Number, Crossing Number, Discharging Method, Crossing Lemma}
}
Document
DOI: 10.4230/LIPIcs.GD.2024.28
On the Edge Density of Bipartite 3-Planar and Bipartite Gap-Planar Graphs

Authors: Aaron Büngener and Maximilian Pfister

Published in: LIPIcs, Volume 320, 32nd International Symposium on Graph Drawing and Network Visualization (GD 2024)

Abstract
We show that if a bipartite graph G with n ≥ 3 vertices can be drawn in the plane such that (i) each edge is involved in at most three crossings per edge or (ii) each crossing is assigned to one of the two involved edges and each edge is assigned at most one crossing, then G has at most 4n-8 edges. In both cases, this bound is tight up to an additive constant as witnessed by lower-bound constructions. The former result can be used to improve the leading constant for the crossing lemma for bipartite graphs which in turn improves various results such as the biplanar crossing number or the maximum number of edges a bipartite k-planar graph can have.
Cite as

Aaron Büngener and Maximilian Pfister. On the Edge Density of Bipartite 3-Planar and Bipartite Gap-Planar Graphs. In 32nd International Symposium on Graph Drawing and Network Visualization (GD 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 320, pp. 28:1-28:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{bungener_et_al:LIPIcs.GD.2024.28,
  author =	{B\"{u}ngener, Aaron and Pfister, Maximilian},
  title =	{{On the Edge Density of Bipartite 3-Planar and Bipartite Gap-Planar Graphs}},
  booktitle =	{32nd International Symposium on Graph Drawing and Network Visualization (GD 2024)},
  pages =	{28:1--28:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-343-0},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{320},
  editor =	{Felsner, Stefan and Klein, Karsten},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.GD.2024.28},
  URN =		{urn:nbn:de:0030-drops-213123},
  doi =		{10.4230/LIPIcs.GD.2024.28},
  annote =	{Keywords: Edge Density, Beyond Planarity, bipartite Graphs, Discharging Method}
}
Document
DOI: 10.4230/LIPIcs.GD.2024.29
Improving the Crossing Lemma by Characterizing Dense 2-Planar and 3-Planar Graphs

Authors: Aaron Büngener and Michael Kaufmann

Published in: LIPIcs, Volume 320, 32nd International Symposium on Graph Drawing and Network Visualization (GD 2024)

Abstract
The classical Crossing Lemma by Ajtai et al. and Leighton from 1982 gave an important lower bound of cm³/n² for the number of crossings in any drawing of a given graph of n vertices and m edges. The original value was c = 1/100, which then has gradually been improved. Here, the bounds for the density of k-planar graphs played a central role. Our new insight is that for k = 2,3 the k-planar graphs have substantially fewer edges if specific local configurations that occur in drawings of k-planar graphs of maximum density are forbidden. Therefore, we are able to derive better bounds for the crossing number cr(G) of a given graph G. In particular, we achieve a bound of cr(G) ≥ 73/18m-305/18(n-2) for the range of 5n < m ≤ 6n, while our second bound cr(G) ≥ 5m - 407/18(n-2) is even stronger for larger m > 6n. For m > 6.79n, we finally apply the standard probabilistic proof from the BOOK and obtain an improved constant of c > 1/27.61 in the Crossing Lemma. Note that the previous constant was 1/29. Although this improvement is not too impressive, we consider our technique as an important new tool, which might be helpful in various other applications.
Cite as

Aaron Büngener and Michael Kaufmann. Improving the Crossing Lemma by Characterizing Dense 2-Planar and 3-Planar Graphs. In 32nd International Symposium on Graph Drawing and Network Visualization (GD 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 320, pp. 29:1-29:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{bungener_et_al:LIPIcs.GD.2024.29,
  author =	{B\"{u}ngener, Aaron and Kaufmann, Michael},
  title =	{{Improving the Crossing Lemma by Characterizing Dense 2-Planar and 3-Planar Graphs}},
  booktitle =	{32nd International Symposium on Graph Drawing and Network Visualization (GD 2024)},
  pages =	{29:1--29:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-343-0},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{320},
  editor =	{Felsner, Stefan and Klein, Karsten},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.GD.2024.29},
  URN =		{urn:nbn:de:0030-drops-213136},
  doi =		{10.4230/LIPIcs.GD.2024.29},
  annote =	{Keywords: Crossing Lemma, k-planar graphs, discharging method}
}
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