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XCSP3 Specifications


XCSP3 is an XML-based format designed to represent combinatorial constrained problems. XCSP3

  • is compact, easy to read and to parse,
  • captures the structure of the problem models,
  • introduces a limited set of basic constraint forms, and allows many variations of them,
  • supports many frameworks introduced in the litterature: CSP, COP, WCSP, QCSP, DisCSP, SCSP, ...

See full specifications.


This is a subset of XCSP3, composed of the main concepts of Constraint Programming (although, of course, this is quite subjective). The interest of XCSP3-core is multiple:

  • focusing on the most popular constraints,
  • facilitating parsing through dedicated parsers in Java and C++,
  • defining a core format for future competitions of constraint solvers.

See core specifications

XCSP3-core, targeted for CSP (Constraint Satisfaction Problem) and COP (Constrained Optimization problem), handles integer variables, mono-objective optimization, and 20 important constraints:

Importantly, as for full XCSP3, the structure of problems (models) can be preserved in XCSP3-core thanks to the following mechanisms:

  • a Java 8 parser for XCSP3-core (and also for XCSP3-full)
  • a C++ parser for XCSP3-core