## Abstract

The (discrete) Fréchet distance (DFD) is a popular similarity measure for curves. Often the input curves are not aligned, so one of them must undergo some transformation for the distance computation to be meaningful. Ben Avraham et al. [5] presented an O(m^{3}n^{2}(1+log(n/m)) log(m+ n))-time algorithm for DFD between two sequences of points of sizes m and n in the plane under translation. In this paper we consider two variants of DFD, both under translation. For DFD with shortcuts in the plane, we present an O(m^{2}n^{2} log^{2}(m + n))-time algorithm, by presenting a dynamic data structure for reachability queries in the underlying directed graph. In 1D, we show how to avoid the use of parametric search and remove a logarithmic factor from the running time of (the 1D versions of) these algorithms and of an algorithm for the weak discrete Fréchet distance; the resulting running times are thus O(m^{2}n(1 + log(n/m))), for the discrete Fréchet distance, and O(mn log(m + n)), for its two variants. Our 1D algorithms follow a general scheme introduced by Martello et al. [21] for the Balanced Optimization Problem (BOP), which is especially useful when an e cient dynamic version of the feasibility decider is available. We present an alternative scheme for BOP, whose advantage is that it yields e cient algorithms quite easily, without having to devise a specially tailored dynamic version of the feasibility decider. We demonstrate our scheme on the most uniform path problem (significantly improving the known bound), and observe that the weak DFD under translation in 1D is a special case of it.

Original language | English |
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Title of host publication | 16th Scandinavian Symposium and Workshops on Algorithm Theory, SWAT 2018 |

Editors | David Eppstein |

Publisher | Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing |

Pages | 201-2014 |

Number of pages | 1814 |

ISBN (Electronic) | 9783959770682 |

DOIs | |

State | Published - 1 Jun 2018 |

Externally published | Yes |

Event | 16th Scandinavian Symposium and Workshops on Algorithm Theory, SWAT 2018 - Malmo, Sweden Duration: 18 Jun 2018 → 20 Jun 2018 |

### Publication series

Name | Leibniz International Proceedings in Informatics, LIPIcs |
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Volume | 101 |

ISSN (Print) | 1868-8969 |

### Conference

Conference | 16th Scandinavian Symposium and Workshops on Algorithm Theory, SWAT 2018 |
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Country/Territory | Sweden |

City | Malmo |

Period | 18/06/18 → 20/06/18 |

### Bibliographical note

Researcher preferred not to include this item in her cv for the time being## Keywords

- Algorithms
- BOP
- Discrete Fréchet distance
- Phrases curve similarity
- Translation