PTHG-22: The Sixth Workshop on Progress Towards the Holy Grail

August 1, 2022, at CP2022, part of FLoC 2022

Note: There is now a PTHGCP Google Group, for news and discussion related to PTHG topics (not just the Workshop). Please join! A playlist of videos of the talks for last year’s Workshop, PTHG-21, including the results of the Constraint Acquisition Challenge, is available here. Individual links to videos and papers are included in the online proceedings here

This Workshop is one of a series. It is hoped that this year’s Workshop will be hybrid, permitting both physical and virtual attendance; further information will be forthcoming. A PTHG-22 Constraint Acquisition Challenge is also planned. 


In 1996 the paper “In Pursuit of the Holy Grail” (also here) proposed that Constraint Programming was well-positioned to pursue the Holy Grail of computer science: the user simply states the problem and the computer solves it. It was followed about a decade later by “Holy Grail Redux“, and then about a decade after that by “Progress Towards the Holy Grail“. This series of workshops aims to encourage and disseminate progress towards that goal, in particular regarding work on automating:

  • Problem Acquisition: user interaction, learning from examples, model reformulation, debugging, maintenance, etc.
  • Solver Construction: tuning parameters, selecting from portfolios, learning heuristics, deep learning, etc.
  • User Explanation: reasons for failure, comparison of alternatives, implications for choices, bias detection, suggested modifications, visualization, etc.

Of particular interest is the intersection of the Holy Grail goal with the increasing attention being paid to machine learning, explainable AI, and human-centric AI.


Submissions may be of any length, and in any format. They may be abstracts, position papers, technical papers, or demos. They may review your own previous work or survey a topic area. They may present new research or suggest directions for further progress. They may propose research roadmaps, demonstration domains, or collaborative projects. They may be proposals for measuring progress, and, in particular, for data sets or competitions to stimulate and compare progress. 

Previously Published Track. Authors are encouraged to submit to this track pointers to relevant papers that they have published elsewhere since the date of the last workshop, PTHG-20, September 7, 2020. The objective is to further the Workshop goal of disseminating progress in this area. 

Submissions should be emailed, in PDF form, with subject line “PTHG-22 Submission”, directly to the Workshop chair, at:

Submissions to the Previously Published Track should be in the form of a PDF that clearly identifies it as a submission to the Previously Published Track, contains bibliographic information on the previous publication, and provides a URL pointing to the paper (if possible without violating copyright, to a full version of the paper).

Authors may make multiple submissions if they wish. All submissions that appropriately address the topic of the workshop will be accepted as is, without further revision, and will be made available at the workshop website.

At least one author of every accepted submission must attend the workshop and pay the workshop fees; otherwise the presentation (and submission) will be withdrawn from the proceedings (if any) and program. Further information about video requirements, if any, will be forthcoming.

Submission deadline: 6 June 2022
Acceptance notifications: 13 June 2022

PTHG-22 Constraint Acquisition Challenge: 
Information on this year’s Challenge will be forthcoming. 

Organizing Committee:

Chair: Eugene Freuder, University College Cork, Ireland,
Christian Bessiere, University of Montpellier, France
Tias Guns, KU Leuven, Belgium
Lars Kotthoff, University of Wyoming, USA 
Ian Miguel, University of St Andrews, Scotland 
Michela Milano, University of Bologna, Italy
Helmut Simonis, University College Cork, Ireland