HPlan 2026:
The 9th ICAPS Workshop on 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
  • techniques for automated learning and synthesis of hierarchical models
  • using Generative AI (like, e.g., LLMs) for hierarchical planning or modeling

Important Dates

  • Abstract Submission: Thursday, 30 April
  • Paper Submission: Monday, 4 May
  • Author Notification: Monday, 1 June
  • Camera-Ready, first version: 22 June (will go online before the workshop)
  • Camera-Ready, final version: 9 July (replaces the first version; goes online shortly after)
  • Workshop: Monday, 29 June, 2026 (timing see below)

Should you require a specific notification date to support your travel plans, please reach out.

Submission Details

The formatting guidelines (author kit, etc.) are the same as for ICAPS 2026. There will be a high quality double-blind review process against the standard 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 like 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 make and 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 9, resp. 5, pages can be used for the paper.

Submissions are done via easychair.

Double Submissions

We encourage the submission of papers that, at the time of submission, are under review at another conference such as SoCS and NeurIPS, for example. However, if the paper is also accepted at the respective conference, it will not be included in our proceedings (you will have to let us know in that case). Such papers will be included into the program, but the proceedings will only contain a link to the respective conference's version. (Accepted NeurIPS papers will still be included in our proceedings since the workshop takes place long before NeurIPS notification.)

Invited Talk

Lee McCluskey

Real-world AI Planning Applications need HTN: True or False?

In this talk I will investigate the potential advantages that hierarchical and other representational mechanisms bring to alleviate the problems of size and structural complexity found in real-world applications. I will review language-related features, and relate these to the effectiveness of knowledge engineering and maintenance of domain models, as well as to the efficiency of plan generation, and to system-wide features such as system evolution and re-use. I will anchor these observations with examples taken from real-world scenarios, ranging from feasibility studies to planning deployed operationally for commercial benefit. This background will lead to the evaluation of hierarchy and transition networks in the context of a whole range of features required in real-world planning.

Lee McCluskey is Research Lead at SimplifAI Systems Ltd where he implements software to generate plans that control collections of connected urban road traffic signals. These generated plans may be aimed at solving some specific goals of a transport operator, or a general goal such as the overall minimisation of traffic delay. Previously he was Professor of Software Technology at the University of Huddersfield. He was awarded a PhD in Machine Learning and Planning in the late 1980s, and since then has published around two hundred papers in the areas of machine learning, planning, formal methods and knowledge engineering. He has been heavily involved in applications of AI within areas such as Air Traffic Control, Road Traffic Management, Railway Maintenance, Well Drilling and Computer Security.


Program

The program will be announced shortly before the workshop. For now, we know that:

  • It takes place on Monday, 29th, from 13:30 to 17:0014:00 to 17:30, in room 3, with a coffee break from 15:30–15:50.
  • We will have one exciting invited talk (see above), 1 hour including Q&A
  • Program:
    • 14:00 - 14:05 Welcome
    • 14:05 - 15:05 Invited talk by Lee McClusky (including Q&A)
    • 15:05 - 15:30 4 previously accepted papers (discussion taken into the break)
    • 15:30 - 15:50 Break
    • 15:50 - 17:30 accepted HPlan papers (schedule to be announced)

Detailed program schedule will be provided closely after June 10th.

Accepted Papers

We give our authors a short period after the conference (roughly one week) to make updates to their papers in case they receive helpful feedback during the workshop/conference. We hence publish the entire proceedings after that time window. Note that we include page numbers due to these proceedings, but like in all years, all papers are non-archival.

Accepted at HPlan

Presentations of papers from other venues

In each year, we allow the presentation of papers that have previously been accepted at another venue. This allows authors to present their work directly to the hierarchical planning community. (Sometimes we also poke people encouraging them to do this; but everybody can reach out ans ask!)

Program Committee

  • Ron Alford, MITRE, US
  • Roman Barták, Charles University, Czech Republic
  • Pascal Bercher, Australian National University, Australia
  • Arthur Bit-Monnot, LAAS-CNRS, University of Toulouse, France
  • Cornelius Brand, Universität Regensburg, Germany
  • Rafael Cardoso, University of Aberdeen, UK
  • David Chan, University of Maryland, US
  • Birte Glimm, Ulm University, Germany
  • Robert Goldman, SIFT, US
  • Daniel Höller, Saarland University, Germany
  • Prakash Jamakatel, University of the Bundeswehr Munich, Germany
  • Ngoc La, MIT, US
  • Pascal Lauer, Saarland University, Germany and ANU, Australia
  • Alexander Lodemann, Ulm University, Germany
  • Daniel Lutalo, Australian National University, Australia
  • Jakub Med, Czech Technical University, Czech Republic
  • Harrison Oates, Australian National University, Australia
  • Conny Olz, Independent Researcher, Germany
  • Kristýna Pantucková, Charles University, Czech Republic
  • Damien Pellier, University of Grenoble Alpes, France
  • Tikhon Pshenitsyn, Steklov Mathematical Institute, Russia
  • Victor Scherer Putrich, Universität des Saarlandes, Germany
  • Gaspard Quenard, University of Grenoble Alpes, France
  • Tobias Schwartz, University of Lübeck, Germany
  • Michael Staud, Ulm University, Germany
  • Michael Welt, Ulm University, Germany
  • Zhanhao Xiao, Guangdong Polytechnic Normal University, China
  • Mohammad Yousefi, Australian National University, Australia
  • Paul Zaidins, University of Maryland, US

Organizing Committee

Further Information

  • New to HTN planning? Reach out! :) And submit your work! Our review process is very high-value, usually of higher quality than at any top-tier conference -- since we select hierarchical planning exerts for the program committee and and have a low reviewing load, allowing for detailed and high-quality reviews with at least 3 reviews per paper, in rare cases even 4.
  • Are you interested in presenting your already published work? Reach out to us! (Also for next years!) Note that your paper does not have to be accepted in the same year; just reach out if you have a paper that you would like to highlight.
  • Do you want to join our team of reviewers? (Maybe even next year?) Please reach out to us! Please note that we try the average number of reviews per reviewer to be at most 1.5 on average, allowing you to fully concentrate on just one paper!
  • On the HPlan series website https://hplan.hierarchical-task.net you find, among others, a list of bibtex entries for all accepted papers in all HPlan editions. Individual workshop pages of past editions are available by adding the respective year, e.g., you may use hplan2025.hierarchical-task.net for last year's edition (or hplan2026.hierarchical-task.net for this exact page).
  • We have a mailing list (via google groups) for hierarchical planning with currently (date: June 2nd, 2026) exactly 99 subscribers. Be number 100! The list is almost zero traffic (in some years it is literally zero), moderated, and only allows mails related to hierarchical planning! Interested? Drop Pascal an email.