13th International Workshop on Confluence
9 July, 2024, Tallinn

IWC 2024

13th International Workshop on Confluence

9th July, 2024, Tallinn, Estonia

Collocated with FSCD 2024



Confluence provides a general notion of determinism and has been conceived as one of the central properties of rewriting systems. Confluence relates to many topics of rewriting (completion, modularity, termination, commutation, etc.) and has been investigated in many formalisms of rewriting, such as first-order rewriting, lambda-calculi, higher-order rewriting, constraint rewriting, conditional rewriting, and so on. Recently there is a renewed interest in confluence research, resulting in new techniques, tool support, confluence competition, and certification as well as in new applications. The scope of the workshop is all these aspects of confluence and related topics.

The goal of the workshop is to provide a forum for researchers interested in the topic of confluence to exchange and share new developments in the field. The workshop will enable discussion on theoretical results, new problems, applications, implementations and benchmarks, and share the current state-of-the-art on the development of confluence tools.

Topics are thus:

The 13th Confluence Competition CoCo 2024 will run live during IWC 2024.

Invited Speaker

Aart Middeldorp, University of Innsbruck
Confluence of Logically Constrained Rewrite Systems

Logically constrained rewrite systems are a natural extension of plain term rewrite systems with native support for constraints that are handled by SMT solvers. In this talk, which is based on joint work with Jonas Schö̈pf and Fabian Mitterwallner, we provide an overview of the confluence results for logically constrained rewrite systems reported in the literature.

Accepted Papers


The proceedings are available online and include reports on the Confluence Competition 2024.


Session 1 (chair: Nao Hirokawa)
9:00-10:00   Aart Middeldorp (Invited talk)
  Confluence of Logically Constrained Rewrite Systems (slides)
10:00-10:30 coffee break
Session 2 (chair: Thiago Felicissimo)
10:30-11:00 Misaki Kojima and Naoki Nishida
  On Proving Confluence of Concurrent Programs by All-Path Reachability of LCTRSs (paper, slides)
11:00-11:30 Salvador Lucas
  From Subtree Replacement Systems to Term Rewriting Systems: a Roadmap to Orthogonality (paper, slides)
11:30-12:00 Vincent van Oostrom
  The problem of the calissons, by rewriting (paper, slides)
12:00-12:30 Salvador Lucas
  A Roadmap to Orthogonality of Conditional Term Rewriting Systems (paper, slides)
12:30-14:00 lunch
Session 3 (chair: Naoki Nishida)
14:00-14:30 Ievgen Ivanov
  On Non-triviality of the Hierarchy of Decreasing Church-Rosser Abstract Rewriting Systems (paper, slides)
14:30-15:25 Aart Middeldorp
  CoCo 2024 (paper, slides)
15:25-15:30 Business meeting
15:30-16:00 coffee break
Session 4 (chair: Misaki Kojima)
16:00-16:30 Salvador Lucas
  Orthogonality of Generalized Term Rewriting Systems (paper, slides)
16:30-17:00 Thiago Felicissimo
  Second-order Church-Rosser modulo, without normalization (paper, slides)
17:00-17:30 Nao Hirokawa and Kiraku Shintani
  Rule Removal for Confluence (paper, slides)
17:30-18:00 Vincent van Oostrom
  Confluence by the Z-property for De Bruijn's lambda-calculus with nameless dummies, based on PLFA (paper, slides)

Important Dates

submission (abstract): 1st May, 2024
submission (paper): 1st May, 2024
pre-notification: before 17th May, 2024 (the deadline of the early registration of FSCD 2024)
notification: 31st May, 2024
final version: June 16th, 2024
workshop: 9th July 2024

(deadlines are AoE)


We solicit short papers or extended abstracts of at most five pages. There will be no formal reviewing. In particular, we welcome short versions of recently published articles and papers submitted elsewhere. The program committee checks relevance and may provide additional feedback. The accepted papers will be made available electronically before the workshop.

The page limit for papers is 5 pages in EasyChair style (6 pages 6 pages excluding references, but 7 pages in total in the final version). Submission is electronically through

Program Committee

Previous IWCs