2026 Quarterly Report 2
This quarterly report contains reminders on the ACP Summer School and CP conference 2026, and several calls.
ACP.1: CP 2026 in Lisbon, Portugal
The International Conference on Principles and Practice of Constraint Programming (CP) is the premier annual conference on all aspects of computing with constraints, including theory, algorithms, models, solvers, and a diverse range of applications in machine learning/artificial intelligence, planning, and scheduling, to name a few. This is the 32nd version of the CP series organized by the Association for Constraint Programming.
This year, CP will be in Lisbon (Portugal), as part of the Federated Logic Conference (FLoC) 2026. A programme overview of the conferences, workshops, summer schools, and competitions at FLoC can be found at https://www.floc26.org/program.
Invited speakers at CP will be Willem-Jan Van Hoeve and Torsten Schaub: https://cp2026.a4cp.org/invited-talks.html
The list of accepted papers is available at https://cp2026.a4cp.org/accepted_papers.html.
Late registration is possible till July 13th through the FLoC website (onsite registration is possible, but it is more expensive). When registering, you will be required to select the main conference you will attend, but you are welcome to attend sessions of any conference taking place in the same week. For details, see: https://www.floc26.org/registration.
ACP.2: Summer School 2026 in Changchun, China
The ACP Summer School 2026 will be hosted by Jilin University and held in Changchun, China. It is organized by CP community members Peter Stuckey and Jimmy Lee.
The dates are set at 24-28 August 2026.
Registration is open till July 7th.
The program, themed "CP: Explanation, Verification and Applications", includes seminars and hands-on lab sessions from key researchers in the field. A hackathon will be also organised, allowing learners to further practise their skills. See the program and more information at https://school.a4cp.org/summer2026/.
ACP.3: Varia
- There was a call for ACP awards for researchers this year: the Distinguished Service, Early Career Researcher and Doctoral Research awards. The winners will be announced at the CP 2026 conference.
- There was a call for Election Statements for the ACP Executive Committee. The results of the election will also be announced at the CP 2026 conference.
- There was also an invitation to the ACP members to vote on a potential new publishing model, which we reproduce below for the record.
See you at CP! The ACP executive committee
Dear ACP member,
Following last year's survey which showed some interest both for a new publishing model and for a transition to a fully open access journal, the EC together with a small committee (Pierre Schaus, Helmut Simonis, Mark Wallace) worked out some details of such a new publishing model.
As a member of the ACP, you are now asked to vote on two questions.
We will use the vote.heliosvoting.org online voting system for voting. You will receive a separate email with login details for the voting site. This email will be sent from the address no-reply@mail.heliosvoting.org in the next hours, so please check your spam folder if you haven't received the email within the next 12 hours!
Voting is private and verifiable (have a look at the details at vote.heliosvoting.org).
You have until July 15 AoE to let us know your opinion about these important potential new directions for our community. The results of the vote will be presented at our general assembly during the CP conference.
Best regards,
Gilles Pesant
ACP president
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Changing our Publishing Model?
Motivation
Open access research: Our community has been discussing for several years the possibility of making our published research open access. In 2020 it was decided to do so for the CP conference (but not yet for the journal) and for the last six years its proceedings have been published by LIPIcs under a diamond open access model: no fees for readers or authors, the small publishing cost being covered by the ACP (3K euros for the whole proceedings).
Struggling Constraints journal: Our community’s journal has difficulty in attracting submissions. This is explained in part by most conference papers from the community not being extended into a journal version or by choosing other journals. Another reason seems to be related to the current publisher, Springer: lack of diamond open access and some recurring issues with typesetting.
Last year the outcome of a survey run by the ACP and presented at the annual general assembly highlighted some of the observations above and showed an interest from the community in considering an alternative publishing model and in moving away from Springer as the publisher of our journal. A small committee then met over the past year in order to work out some details of such a new publishing model so that it could be put to a vote by the community.
New publishing model
Structural organization of the conference and journal: The CP conference would still have a conference chair and various other chairs (workshop, tutorial, doctoral program, ...) but the main technical programming would be transferred over to the journal, so no more program chair nor program committee. On the journal side, an editorial board would substitute for the former conference program committee. Each member would commit to a 2-year term (possibly staggered) of reviewing papers within 6 weeks of submission (possibly with the help of subreviewers). Papers would be assigned by an associate editor (AE) with the understanding that editorial board members tacitly accept this assignment in the same way we currently do for the conference. This avoids the time spent recruiting reviewers for a paper. It would make sense that this AE be appointed for a 1-year term by the ACP EC, as is currently done for the conference program chair. That editor would also appoint half of the editorial board (under a staggered model). Making decisions for all the papers during a year can seem like a lot but, unlike the conference, it would no longer be a matter of selecting the top papers given a target acceptance rate or how many can be accommodated in the schedule but rather deciding if, at the end of the reviewing process, a paper is good enough. If that’s still too much of a workload, subchairs or a small senior editorial board could be appointed, at the discretion of the AE.
Reviewing process: The journal would have hard deadlines for first decision on submissions, 4 times a year. These would induce similar deadlines for authors to submit, e.g. 6 weeks before. We would set a maximum of two rounds of reviewing in order to keep the process relatively short. Authors would be allowed to revise their submission once, after which the verdict should be either Accept (as is or with minor corrections, not sent out to review again) or Reject. This is consistent with journals such as JAIR.
Pros:
- encourages a better outcome from the reviewing process: improved papers from multiple reviewing rounds, less frustration for the authors of a worthy paper not being good enough wrt others to make the selection
- no need for a strict page limit, though we would discourage long papers (25+ pages) in order to keep the reviewing process short
- spreads the reviewing workload over the whole year
- there may be more prestige for reviewers in belonging to a journal editorial board as opposed to a conference program committee
- in some disciplines and institutions, a journal paper is worth much more than a conference paper for career advancement and research funding applications
Cons:
- writing a journal paper may take more time and hence harder for students with a limited time horizon
- may be harder to justify travel funds to attend the conference for students since this is no longer a publication requirement.
- risk of a drop in conference attendance
- loss of ranking: the CP conference currently has an A ranking; the CORE ranking system evaluates the historical prestige, impact, and peer-review rigor of the event and not so much where its proceedings are published; there is a risk that transferring to an existing journal such as Constraints may hurt that ranking, at least temporarily, but perhaps not so with a new open-access journal and there are instances of conferences such as POPL where that transition was seamless
- could we still publish short papers?
New diamond open access (DOA) journal
There are two dominant models for such journals, Open Journal Systems (OJS) and Episciences, the latter offering overlay journals (articles are held in one or more repositories such as arXiv).
Pros:
- Accessibility: DOA incurs no fee or a minimal one usually covered by an institution. Constraints is a Springer Hybrid Journal, at 2,590 euros per paper for optional open access. If the journal became a Springer Full Open Access Journal with mandatory open access, it seems this fee could be lowered (some of their journals ask about 1200 euros per paper).
- Avoid exploitation by commercial publishers: this removes the commercial publisher who is making significant profit at the expense of researchers who are doing most of the work for free.
Cons:
- Indexing: Constraints is indexed by Scopus, Web of Science, IEEE xplore, Google Scholar. A new journal might only be indexed by Google Scholar, DOAJ, OpenCitations, CrossRef. Being indexed by Scopus and Web of Science may happen after a few years, e.g. Theory of Computing published by EpiSciences.
- Loss of control over Constraints: The Constraints journal does not belong to the ACP but to Springer; even if the community adopts a new journal, Springer could very well decide to continue publishing Constraints with a fresh and not necessarily representative editorial board.
- If we simply create a new open-access journal without changing our publishing model, the problem of low number of submissions to the journal will likely remain.
The vote
We ask the community to vote on two separate questions.
Question 1: New publishing model
I agree to transition to a new publishing model for our community, as outlined above, i.e., papers are submitted to a journal and accepted papers are offered a presentation spot at the CP conference.
Question 2: New DOA journal
I agree to create a new diamond open access journal for our community.