# XCSP3: An Integrated Format for Benchmarking Combinatorial Constrained Problems

arXiv: https://arxiv.org/abs/1611.03398 · HTML: https://mlsanity.com/paper/1611.03398/

## Key facts

- Cited by 7 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 10 Nov 2016.

## Built on by (most cited first, 7 of 7)

- [Reasoning in a Combinatorial and Constrained World: Benchmarking LLMs on Natural-Language Combinatorial Optimization](https://mlsanity.com/paper/2602.02188/) (2026)
- [ACE, a generic constraint solver](https://mlsanity.com/paper/2302.05405/) (2023)
- [Proceedings of the 2022 XCSP3 Competition](https://mlsanity.com/paper/2209.00917/) (2022)
- [Proceedings of the 2023 XCSP3 Competition](https://mlsanity.com/paper/2312.05877/) (2023)
- [CP-Model-Zoo: A Natural Language Query System for Constraint Programming Models](https://mlsanity.com/paper/2509.07867/) (2025)
- [Sequence Variables: A Constraint Programming Computational Domain for Routing and Sequencing](https://mlsanity.com/paper/2510.09373/) (2025)
- [PyCSP3-Scheduling: A Scheduling Extension for PyCSP3](https://mlsanity.com/paper/2605.14559/) (2026)

## Abstract (arXiv)

We propose a major revision of the format XCSP 2.1, called XCSP3, to build integrated representations of combinatorial constrained problems. This new format is able to deal with mono/multi optimization, many types of variables, cost functions, reification, views, annotations, variable quantification, distributed, probabilistic and qualitative reasoning. The new format is made compact, highly readable, and rather easy to parse. Interestingly, it captures the structure of the problem models, through the possibilities of declaring arrays of variables, and identifying syntactic and semantic groups of constraints. The number of constraints is kept under control by introducing a limited set of basic constraint forms, and producing almost automatically some of their variations through lifting, restriction, sliding, logical combination and relaxation mechanisms. As a result, XCSP3 encompasses practically all constraints that can be found in major constraint solvers developed by the CP community. A website, which is developed conjointly with the format, contains many models and series of instances. The user can make sophisticated queries for selecting instances from very precise criteria. The objective of XCSP3 is to ease the effort required to test and compare different algorithms by providing a common test-bed of combinatorial constrained instances.