Min st-Cut Oracle for Planar Graphs with Near-Linear Preprocessing Time. Borradaile, G., Sankowski, P., & Wulff-Nilsen, C. ACM Trans. Algorithms, 11(3):16:1--16:29, ACM, New York, NY, USA, January, 2015.
Min st-Cut Oracle for Planar Graphs with Near-Linear Preprocessing Time [link]Paper  doi  abstract   bibtex   
For an undirected n-vertex planar graph G with nonnegative edge weights, we consider the following type of query: given two vertices s and t in G, what is the weight of a min st-cut in G? We show how to answer such queries in constant time with O(n log4 n) preprocessing time and O(n log n) space. We use a Gomory-Hu tree to represent all the pairwise min cuts implicitly. Previously, no subquadratic time algorithm was known for this problem. Since all-pairs min cut and the minimum-cycle basis are dual problems in planar graphs, we also obtain an implicit representation of a minimum-cycle basis in O(n log4 n) time and O(n log n) space. Additionally, an explicit representation can be obtained in O(C) time and space where C is the size of the basis. These results require that shortest paths are unique. This can be guaranteed either by using randomization without overhead or deterministically with an additional log2 n factor in the preprocessing times.
@article{ borradaile2015stcut,
  abstract = {For an undirected n-vertex planar graph G with nonnegative edge weights, we consider the following type of query: given two vertices s and t in G, what is the weight of a min st-cut in G? We show how to answer such queries in constant time with O(n log4 n) preprocessing time and O(n log n) space. We use a Gomory-Hu tree to represent all the pairwise min cuts implicitly. Previously, no subquadratic time algorithm was known for this problem. Since all-pairs min cut and the minimum-cycle basis are dual problems in planar graphs, we also obtain an implicit representation of a minimum-cycle basis in O(n log4 n) time and O(n log n) space. Additionally, an explicit representation can be obtained in O(C) time and space where C is the size of the basis. These results require that shortest paths are unique. This can be guaranteed either by using randomization without overhead or deterministically with an additional log2 n factor in the preprocessing times.},
  acmid = {2684068},
  added-at = {2015-01-16T11:08:14.000+0100},
  address = {New York, NY, USA},
  articleno = {16},
  author = {Borradaile, Glencora and Sankowski, Piotr and Wulff-Nilsen, Christian},
  biburl = {http://www.bibsonomy.org/bibtex/266e29caa1b488884b55894d11d2655a1/mtv_test},
  description = {Min st-Cut Oracle for Planar Graphs with Near-Linear Preprocessing Time},
  doi = {10.1145/2684068},
  interhash = {3906a74d83806c044e54927d2a51c36f},
  intrahash = {66e29caa1b488884b55894d11d2655a1},
  issn = {1549-6325},
  issue_date = {January 2015},
  journal = {ACM Trans. Algorithms},
  keywords = {cut oracle planar st},
  month = {January},
  number = {3},
  numpages = {29},
  pages = {16:1--16:29},
  publisher = {ACM},
  title = {Min st-Cut Oracle for Planar Graphs with Near-Linear Preprocessing Time},
  url = {http://doi.acm.org/10.1145/2684068},
  volume = {11},
  year = {2015}
}

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