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Documents authored by Ozel, Evrim


Document
Noisy Sorting Without Searching: Data Oblivious Sorting with Comparison Errors

Authors: Ramtin Afshar, Michael Dillencourt, Michael T. Goodrich, and Evrim Ozel

Published in: LIPIcs, Volume 265, 21st International Symposium on Experimental Algorithms (SEA 2023)


Abstract
We provide and study several algorithms for sorting an array of n comparable distinct elements subject to probabilistic comparison errors. In this model, the comparison of two elements returns the wrong answer according to a fixed probability, p_e < 1/2, and otherwise returns the correct answer. The dislocation of an element is the distance between its position in a given (current or output) array and its position in a sorted array. There are various algorithms that can be utilized for sorting or near-sorting elements subject to probabilistic comparison errors, but these algorithms are not data oblivious because they all make heavy use of noisy binary searching. In this paper, we provide new methods for sorting with comparison errors that are data oblivious while avoiding the use of noisy binary search methods. In addition, we experimentally compare our algorithms and other sorting algorithms.

Cite as

Ramtin Afshar, Michael Dillencourt, Michael T. Goodrich, and Evrim Ozel. Noisy Sorting Without Searching: Data Oblivious Sorting with Comparison Errors. In 21st International Symposium on Experimental Algorithms (SEA 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 265, pp. 8:1-8:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2023)


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@InProceedings{afshar_et_al:LIPIcs.SEA.2023.8,
  author =	{Afshar, Ramtin and Dillencourt, Michael and Goodrich, Michael T. and Ozel, Evrim},
  title =	{{Noisy Sorting Without Searching: Data Oblivious Sorting with Comparison Errors}},
  booktitle =	{21st International Symposium on Experimental Algorithms (SEA 2023)},
  pages =	{8:1--8:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-279-2},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{265},
  editor =	{Georgiadis, Loukas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2023.8},
  URN =		{urn:nbn:de:0030-drops-183585},
  doi =		{10.4230/LIPIcs.SEA.2023.8},
  annote =	{Keywords: sorting, algorithms, randomization, experimentation}
}
Document
Efficient Exact Learning Algorithms for Road Networks and Other Graphs with Bounded Clustering Degrees

Authors: Ramtin Afshar, Michael T. Goodrich, and Evrim Ozel

Published in: LIPIcs, Volume 233, 20th International Symposium on Experimental Algorithms (SEA 2022)


Abstract
The completeness of road network data is significant in the quality of various routing services and applications. We introduce an efficient randomized algorithm for exact learning of road networks using simple distance queries, which can find missing roads and improve the quality of routing services. The efficiency of our algorithm depends on a cluster degree parameter, d_max, which is an upper bound on the degrees of vertex clusters defined during our algorithm. Unfortunately, we leave open the problem of theoretically bounding d_max, although we conjecture that d_max is small for road networks and other similar types of graphs. We support this conjecture by experimentally evaluating our algorithm on road network data for the U.S. and 5 European countries of various sizes. This analysis provides experimental evidence that our algorithm issues a quasilinear number of queries in expectation for road networks and similar graphs.

Cite as

Ramtin Afshar, Michael T. Goodrich, and Evrim Ozel. Efficient Exact Learning Algorithms for Road Networks and Other Graphs with Bounded Clustering Degrees. In 20th International Symposium on Experimental Algorithms (SEA 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 233, pp. 9:1-9:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


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@InProceedings{afshar_et_al:LIPIcs.SEA.2022.9,
  author =	{Afshar, Ramtin and Goodrich, Michael T. and Ozel, Evrim},
  title =	{{Efficient Exact Learning Algorithms for Road Networks and Other Graphs with Bounded Clustering Degrees}},
  booktitle =	{20th International Symposium on Experimental Algorithms (SEA 2022)},
  pages =	{9:1--9:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-251-8},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{233},
  editor =	{Schulz, Christian and U\c{c}ar, Bora},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2022.9},
  URN =		{urn:nbn:de:0030-drops-165432},
  doi =		{10.4230/LIPIcs.SEA.2022.9},
  annote =	{Keywords: Road Networks, Exact Learning, Graph Reconstruction, Randomized Algorithms}
}
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