Preprocessing Parallelization for the ALT-Algorithm

Genaro Peque, Junji Urata, Takamasa Iryo

Research output: Chapter in Book/Report/Conference proceedingConference contribution


In this paper, we improve the preprocessing phase of the ALT algorithm through parallelization. ALT is a preprocessing-based, goal-directed speed-up technique that uses A* (A star), Landmarks and Triangle inequality which allows fast computations of shortest paths (SP) in large-scale networks. Although faster techniques such as arc-flags, SHARC, Contraction Hierarchies and Highway Hierarchies already exist, ALT is usually combined with these faster algorithms to take advantage of its goal-directed search to further reduce the SP search computation time and its search space. However, ALT relies on landmarks and optimally choosing these landmarks is NP-hard, hence, no effective solution exists. Since landmark selection relies on constructive heuristics and the current SP search speed-up is inversely proportional to landmark generation time, we propose a parallelization technique which reduces the landmark generation time significantly while increasing its effectiveness.

Original languageEnglish
Title of host publicationComputational Science – ICCS 2018 - 18th International Conference, Proceedings
EditorsJack Dongarra, Haohuan Fu, Valeria V. Krzhizhanovskaya, Michael Harold Lees, Peter M. Sloot, Yong Shi, Yingjie Tian
PublisherSpringer Verlag
Number of pages13
ISBN (Print)9783319937120
Publication statusPublished - 2018
Externally publishedYes
Event18th International Conference on Computational Science, ICCS 2018 - Wuxi, China
Duration: 2018 Jun 112018 Jun 13

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume10862 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference18th International Conference on Computational Science, ICCS 2018


  • ALT algorithm
  • Large-scale traffic simulation
  • Shortest path search

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


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