The PPDP 2021 symposium brings together researchers from thedeclarative programming communities, including those working in the functional, logic, answer-set, and constraint handling programming paradigms. The goal is to stimulate research in the use of logical formalisms and methods for analyzing, performing, specifying, andreasoning about computations, including mechanisms for concurrency,security, static analysis, and verification.

Submissions are invited on all topics related to declarative programming,from principles to practice, from foundations to applications. Topics of interest include, but are not limited to

• Language Design: domain-specific languages; interoperability;   concurrency, parallelism and distribution; modules; functional   languages; reactive languages; languages with objects; languages for   quantum computing; languages inspired by biological and chemical   computation; metaprogramming.
• Declarative languages in artificial intelligence: logic programming;   database languages; knowledge representation languages;   probabilistic languages; differentiable languages.
• Implementations: abstract machines; interpreters; compilation;   compile-time and run-time optimization; memory management.
• Foundations: types; logical frameworks; monads and effects; semantics.
• Analysis and Transformation: partial evaluation; abstract interpretation;   control flow; data flow; information flow; termination analysis; resource   analysis; type inference and type checking; verification; validation;   debugging; testing.
• Tools and Applications: programming and proof environments;   verification tools; case studies in proof assistants or interactive   theorem provers; certification; novel applications of declarative   programming inside and outside of CS; declarative programming   pearls; practical experience reports and industrial application;   education.

The PC chair will be happy to advise on the appropriateness of a topic.

PPDP 2021 will be co-located with the 31st International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2021).

Submission Guidelines

Submissions can be made in three categories:

• Research Papers must present original research which isunpublished and not submitted elsewhere. They must not exceed 12 pagesACM style 2-column (including figures, but excluding bibliography).Work that already appeared in unpublished or informallypublished workshop proceedings may be submitted (please contact the PCchair in case of questions). Research papers will be judged onoriginality, significance, correctness, clarity, and readability.
• System Descriptions must describe a working system whosedescription has not been published or submitted elsewhere. They must not exceed10 pages and should contain a link to a working system. System Descriptions mustbe marked as such at the time of submission and will be judged on originality,significance, usefulness, clarity, and readability.
• Experience Reports are meant to help create a body of published,refereed, citable evidence where declarative programming such as functional,logic, answer-set, constraint programming, etc., is used in practice. They mustnot exceed 5 pages **including references**.  Experience Reports must be markedas such at the time of submission and need not report original research results.They will be judged on significance, usefulness, clarity, and readability.

Supplementary material may be provided via a link to an extendedversion of the submission (recommended), or in a clearly marked appendixbeyond the above-mentioned page limits. Reviewers are not required tostudy extended versions or any material beyond the respective pagelimit.

At least one author of each accepted submission will be expected toattend and present the work at the conference. The PC chair may retracta paper that is not presented. The PC chair may also retract a paper ifcomplaints about the paper's correctness are raised which cannot beresolved by the final paper deadline.

Formatting Guidelines

We plan to use the same publication arrangements as PPDP has had in previous years.

For each paper category, you must use the most recent version of the "CurrentACM Master Template" which is available at<https://www.acm.org/publications/proceedings-template>. The most recent versionat the time of writing is 1.75. You must use the LaTeX sigconf proceedingstemplate as the conference organizers are unable to process final submissions inother formats. In case of problems with the templates, contact ACM's TeX supportteam at Aptara <acmtexsupport@aptaracorp.com>.

Authors should note ACM's statement on author's rights (http://authors.acm.org/)which apply to final papers. Submitted papers should meet the requirements ofACM's plagiarism policy(http://www.acm.org/publications/policies/plagiarism_policy).

Committees

Program Committee Chairs

• Nick Benton, Facebook, UK
• Silvia Ghilezan, University of Novi Sad & Mathematical Institute SASA, Serbia

Program Committee

• Zena Ariola, University of Oregon, USA
• Małgorzata Biernacka, University of Wroclaw, Poland
• James Cheney, The University of Edinburgh, UK
• Stefania Dumbrava, ENSIIE Paris-Evry, France
• Hugo Herbelin, INRIA, France
• Cosimo Laneve, University of Bologna, Italy
• Pierre Lescanne, ENS de Lyon, France
• Ugo de’Liguoro, University of Torino, Italy
• Francesca A. Lisi, University of Bari, Italy
• Yanhong Annie Liu, Stony Brook University, USA
• Elaine Pimentel, Federal University of Rio Grande do Norte, Brazil
• Yukiyoshi Kameyama, University of Tsukuba, Japan
• Petar Maksimovic, Imperial College, London, UK
• Yutaka Nagashima, Yale-NUS College, Singapore & University of Innsbruck, Austria
• Aleksandar Nanevski, IMDEA Software Institute, Spain 
• Vivek Nigam, fortiss GmbH, Germany & Federal University of Paraíba, Brazil
• Jorge A. Pérez, University of Groningen, The Netherlands
• Sanjiva Prasad, Indian Institute of Technology Delhi, India
• Alexis Saurin, IRIF -- CNRS, Université de Paris & INRIA, France
• Tom Schrijvers, KU Leuven, The Netherlands
• Paul Tarau, University of NorthTexas, USA
• Tarmo Uustalu, Reykjavik University, Island & Tallinn University of Technology, Estonia

Organizing Committee Chair

•  Niccolò Veltri, Tallinn University of Technology, Estonia

Steering Committee Chair

•  James Cheney, The University of Edinburgh, UK

Invited Speakers

TBA

Publication

We plan to use the same publication arrangements as PPDP has had in previous years.

Venue

The conference will be organised by Tallinn University of Technology, Tallinn, Estonia. It will be decided in due time whether the conference will be in person, virtual or hybrid. More information will be available upon decission.

Contact

All questions about submissions should be emailed to the program chair Silvia Ghilezan <gsilvia@uns.ac.rs>.

All questions about local information should be emailed to the local organiser Niccolò Veltri <niccolo@cs.ioc.ee>.