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Documents authored by Wang, Qing

Document
DOI: 10.4230/LIPIcs.SWAT.2022.7
On the Visibility Graphs of Pseudo-Polygons: Recognition and Reconstruction

Authors: Safwa Ameer, Matt Gibson-Lopez, Erik Krohn, and Qing Wang

Published in: LIPIcs, Volume 227, 18th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT 2022)

Abstract
We give polynomial-time algorithms that solve the pseudo-polygon visibility graph recognition and reconstruction problems. Our algorithms are based on a new characterization of the visibility graphs of pseudo-polygons.
Cite as

Safwa Ameer, Matt Gibson-Lopez, Erik Krohn, and Qing Wang. On the Visibility Graphs of Pseudo-Polygons: Recognition and Reconstruction. In 18th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 227, pp. 7:1-7:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@InProceedings{ameer_et_al:LIPIcs.SWAT.2022.7,
  author =	{Ameer, Safwa and Gibson-Lopez, Matt and Krohn, Erik and Wang, Qing},
  title =	{{On the Visibility Graphs of Pseudo-Polygons: Recognition and Reconstruction}},
  booktitle =	{18th Scandinavian Symposium and Workshops on Algorithm Theory (SWAT 2022)},
  pages =	{7:1--7:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-236-5},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{227},
  editor =	{Czumaj, Artur and Xin, Qin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SWAT.2022.7},
  URN =		{urn:nbn:de:0030-drops-161673},
  doi =		{10.4230/LIPIcs.SWAT.2022.7},
  annote =	{Keywords: Pseudo-Polygons, Visibility Graph Recognition, Visibility Graph Reconstruction}
}
Document
DOI: 10.4230/LIPIcs.SoCG.2020.6
Terrain Visibility Graphs: Persistence Is Not Enough

Authors: Safwa Ameer, Matt Gibson-Lopez, Erik Krohn, Sean Soderman, and Qing Wang

Published in: LIPIcs, Volume 164, 36th International Symposium on Computational Geometry (SoCG 2020)

Abstract
In this paper, we consider the Visibility Graph Recognition and Reconstruction problems in the context of terrains. Here, we are given a graph G with labeled vertices v₀, v₁, …, v_{n-1} such that the labeling corresponds with a Hamiltonian path H. G also may contain other edges. We are interested in determining if there is a terrain T with vertices p₀, p₁, …, p_{n-1} such that G is the visibility graph of T and the boundary of T corresponds with H. G is said to be persistent if and only if it satisfies the so-called X-property and Bar-property. It is known that every "pseudo-terrain" has a persistent visibility graph and that every persistent graph is the visibility graph for some pseudo-terrain. The connection is not as clear for (geometric) terrains. It is known that the visibility graph of any terrain T is persistent, but it has been unclear whether every persistent graph G has a terrain T such that G is the visibility graph of T. There actually have been several papers that claim this to be the case (although no formal proof has ever been published), and recent works made steps towards building a terrain reconstruction algorithm for any persistent graph. In this paper, we show that there exists a persistent graph G that is not the visibility graph for any terrain T. This means persistence is not enough by itself to characterize the visibility graphs of terrains, and implies that pseudo-terrains are not stretchable.
Cite as

Safwa Ameer, Matt Gibson-Lopez, Erik Krohn, Sean Soderman, and Qing Wang. Terrain Visibility Graphs: Persistence Is Not Enough. In 36th International Symposium on Computational Geometry (SoCG 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 164, pp. 6:1-6:13, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{ameer_et_al:LIPIcs.SoCG.2020.6,
  author =	{Ameer, Safwa and Gibson-Lopez, Matt and Krohn, Erik and Soderman, Sean and Wang, Qing},
  title =	{{Terrain Visibility Graphs: Persistence Is Not Enough}},
  booktitle =	{36th International Symposium on Computational Geometry (SoCG 2020)},
  pages =	{6:1--6:13},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-143-6},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{164},
  editor =	{Cabello, Sergio and Chen, Danny Z.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2020.6},
  URN =		{urn:nbn:de:0030-drops-121640},
  doi =		{10.4230/LIPIcs.SoCG.2020.6},
  annote =	{Keywords: Terrains, Visibility Graph Characterization, Visibility Graph Recognition}
}
Document
DOI: 10.4230/DagSemProc.08181.3
Composing Personalised Services on top of Abstract State Services

Authors: Hui Ma, Klaus-Dieter Schewe, Bernhard Thalheim, and Qing Wang

Published in: Dagstuhl Seminar Proceedings, Volume 8181, The Evolution of Conceptual Modeling (2008)

Abstract
We introduce Abstract State Services (ASSs) as an abstraction of data-intensive services that can be made available for use by other systems, e.g. via the web. An ASS combines a hidden database layer with an operation-equipped view layer, and can be anything from a simple function to a full-fledged Web Information System or a Data Warehouse. We adopt the fundamental approach of Abstract State Machines to model ASSs. Then we show how tailored services can be extracted from available ASSs, integrated with other ASSs and personalised to user preferences.
Cite as

Hui Ma, Klaus-Dieter Schewe, Bernhard Thalheim, and Qing Wang. Composing Personalised Services on top of Abstract State Services. In The Evolution of Conceptual Modeling. Dagstuhl Seminar Proceedings, Volume 8181, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2008)

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@InProceedings{ma_et_al:DagSemProc.08181.3,
  author =	{Ma, Hui and Schewe, Klaus-Dieter and Thalheim, Bernhard and Wang, Qing},
  title =	{{Composing Personalised Services on top of Abstract State Services}},
  booktitle =	{The Evolution of Conceptual Modeling},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2008},
  volume =	{8181},
  editor =	{Lois Delcambre and Roland H. Kaschek and Heinrich C. Mayr},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagSemProc.08181.3},
  URN =		{urn:nbn:de:0030-drops-15975},
  doi =		{10.4230/DagSemProc.08181.3},
  annote =	{Keywords: Abstract State Machines, services, integration, composition}
}
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