• Submission deadline: 12 May, 2021 UTC-12
  • Notification: 21 June, 2021
  • Submit


Fourth ICAPS Workshop on Hierarchical Planning (HPlan)

    The motivation for using hierarchical planning formalisms is manifold. It ranges from an explicit and predefined guidance of the plan generation process and the ability to represent complex problem solving and behavior patterns to the option of having different abstraction layers when communicating with a human user or when planning co-operatively. The best-known formalism in the field is Hierarchical Task Network (HTN) planning. In addition, there are several other hierarchical planning formalisms, e.g., hybrid planning (incorporating aspects from POCL planning), Hierarchical Goal Network (HGN) planning (incorporating a hierarchy on goals), or formalisms that combine task hierarchies with timeline planning (e.g. ANML). Hierarchies induce fundamental differences from classical planning, creating distinct computational properties and requiring separate algorithms from non-hierarchical planners. Many of these aspects of hierarchical planning are still unexplored. Thus, we encourage any contribution, independent of the underlying hierarchical planning formalism, and want to provide a forum for researchers to discuss the various aspects of hierarchical planning.

    Topics of interests include but are not limited to:

    • Theoretical foundations, e.g., complexity results
    • Heuristics, search, and other solving techniques for plan generation
    • Techniques and foundations for providing modeling support
    • Challenges and lessons learned from modeling systems (using hierarchical models)
    • Applications of hierarchical planning
    • Plan explanation for hierarchical models
    • Hierarchical plan repair techniques
    • Techniques for verifying solutions of hierarchical planning problems

    Submission Details

    The formatting guidelines (author kit, etc.) are the same as for ICAPS 2021. Like at the main conference, there will be a high quality double-blind review process against the standard ICAPS criteria of significance, soundness, scholarship, clarity, and reproducibility. However, submissions may be less evolved than at the main conference.

    We have two categories:

    1. Technical research papers (short or long) and
    2. Challenge papers (short).

    Technical research papers are standard conference papers, but may be less evolved. The purpose of challenge papers is to report on or to make aware of interesting/important problems in Hierarchical Planning and to encourage discussion at the workshop -- not to present some significant contribution.

    Authors may submit *long papers* (up to 8 pages plus up to one page of references) or *short papers* (up to 4 pages plus up to one page of references). The purpose of short papers is to encourage publications of more preliminary results; challenge papers need to be short papers. In case of acceptance, the full 5, resp. 9, pages can be used for the paper, e.g. to address the reviewers' comments.

    If you are interested in presenting work that was accepted or published at a conference or journal, please contact the organizers. We will not include such a paper into our proceedings, but we are happy to discuss options for presenting such work.

    Submission page: https://easychair.org/conferences/?conf=hplan2021

    Important Dates

    • Paper submission: 12 May (Papers may be updated until 17 May, but they need to be submitted and complete until the 12th. The additional days are only intended for optional minor improvements.)
    • Notification: 21 June
    • Publish list of accepted papers: 22 July
    • Camera-ready paper submission: 26 July
    • Proceedings/papers online: before ICAPS

    The reference timezone for all deadlines is UTC-12, i.e., AOE.

    Invited Talk

    Malik Ghallab, Directeur de recherche emeritus at CNRS
    LAAS-CNRS, 7 Av. Colonel Roche, 31077 Toulouse, France

    Malik Ghallab

    Bio.The research activity of Malik Ghallab is focused on AI and Robotics. He contributed to topics such as knowledge representation and reasoning, planning, and learning of skills and models of behaviors. He (co-)authored over 200 technical papers and several books. He taught AI at a few universities in France and abroad; he advised 32 PhDs. He was director of several AI research programs in France, director of LAAS-CNRS and CTO of INRIA. He chairs the Steering Committee of ANITI, the interdisciplinary AI institute of Toulouse. His is involved in initiatives regarding socially responsible research in AI and computational sciences. He is ECCAI Fellow, and Docteur Honoris Causa of Linköping University, Sweden.

    Title and Abstract

    Will be available soon.


    • In 2020, the International Planning Competition (IPC) was on Hierarchical Task Network Planning. Visit ipc2020.hierarchical-task.net for results, participating planners, planning benchmarks, and more!
    • HPlan has a YouTube channel, which hosts the recorded talks from HPlan 2020 as well as the results presentation of IPC 2020. Recorded talks for future HPlan workshops will be added there as well.
    • We have a mailing list (via google groups) for hierarchical planning with currently approx. 70 subscribers. The list is low traffic, moderated, and only allows mails related to hierarchical planning! Interested? Drop Pascal a mail.

    Previous HPlan workshops

    Previous workshops are available here:

    Or simply http://hplanYYYY.hierarchical-task.net (with YYYY being the year)

    Program Committee

    • Ron Alford
    • Roman Barták
    • Gregor Behnke
    • Pascal Bercher
    • Arthur Bit-Monnot
    • Dillon Chen
    • Lavindra de'Silva
    • Juan Fernández-Olivares
    • Florian Geißer
    • Alban Grastien
    • Daniel Höller
    • Jane Jean Kiam
    • Ugur Kuter
    • Songtuan Lin
    • Mauricio Cecilio Magnaguagno
    • Conny Olz
    • Simona Ondrčková
    • Sunandita Patra
    • Felix Richter
    • Dominik Schreiber
    • Shirin Sohrabi
    • David Speck
    • Alvaro Torralba
    • Julia Wichlacz
    • Zhanhao Xiao

    Organizing Committee