## Abstract

In this paper we consider the decremental single-source shortest paths (SSSP) problem, whereEmail: given a graph G and a source node s the goal is to maintain shortest distances between s and all other nodes in G under a sequence of online adversarial edge deletions. In their seminal work, Even and Shiloach [JACM 1981] presented an exact solution to the problem in unweighted graphs with only O(mn) total update time over all edge deletions. Their classic algorithm was the state of the art for the decremental SSSP problem for three decades, even when approximate shortest paths are allowed. The first improvement over the Even-Shiloach algorithm was given by Bernstein and Roditty [SODA 2011], who for the case of an unweighted and undirected graph presented a (1 + ∈)- approximate algorithm with constant query time and a total update time of O(n^{2}+^{o(1)}). This work triggered a series of new results, culminating in a recent breakthrough of Henzinger, Krinninger and Nanongkai [FOCS 14], who presented a (1+∈)-approximate algorithm for undirected weighted graphs whose total update time is near linear: O(m^{1+o(1)} log(W)), where W is the ratio of the heaviest to the lightest edge weight in the graph. In this paper they posed as a major open problem the question of derandomizing their result. Until very recently, all known improvements over the Even-Shiloach algorithm were randomized and required the assumption of a non-adaptive adversary. In STOC 2016, Bernstein and Chechik showed the first deterministic algorithm to go beyond O(mn) total update time: the algorithm is also (1 + ∈)-approximate, and has total update time Õ (n^{2}). In SODA 2017, the same authors presented an algorithm with total update time Õ(mn^{3/4}). However, both algorithms are restricted to undirected, unweighted graphs. We present the first deterministic algorithm for weighted undirected graphs to go beyond the O(mn) bound. The total update time is Õ (n^{2} log(W)).

Original language | English (US) |
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Title of host publication | 44th International Colloquium on Automata, Languages, and Programming, ICALP 2017 |

Editors | Anca Muscholl, Piotr Indyk, Fabian Kuhn, Ioannis Chatzigiannakis |

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

ISBN (Electronic) | 9783959770415 |

DOIs | |

State | Published - Jul 1 2017 |

Event | 44th International Colloquium on Automata, Languages, and Programming, ICALP 2017 - Warsaw, Poland Duration: Jul 10 2017 → Jul 14 2017 |

### Publication series

Name | Leibniz International Proceedings in Informatics, LIPIcs |
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Volume | 80 |

ISSN (Print) | 1868-8969 |

### Conference

Conference | 44th International Colloquium on Automata, Languages, and Programming, ICALP 2017 |
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Country/Territory | Poland |

City | Warsaw |

Period | 7/10/17 → 7/14/17 |

## Keywords

- Deterministic
- Dynamic algorithms
- Shortest paths
- Weighted graph

## ASJC Scopus subject areas

- Software