konstraint

Konstraint is a constraint programming framework and language designed to model and solve constraint satisfaction problems. It emphasizes declarative problem specification, letting users describe variables, domains, and relationships rather than detailing control flow.

Core concepts include variables with finite domains, constraints that relate variables, and a solver that performs constraint propagation and backtracking search to find feasible solutions.

Global constraints such as allDifferent help express common patterns; support for linear arithmetic, logical constraints, and user-defined propagators allows modeling a wide range of problems.

The language provides a syntax for declaring variables and constraints and supports optimization by minimizing or maximizing objective functions.

Konstraint comprises a core solver engine and bindings to multiple host languages such as Python, JavaScript, and Java, enabling embedding in applications. The engine supports various backends, including constraint propagation, SAT-based search, and hybrid CP-SAT approaches.

Applications span scheduling, timetabling, resource allocation, and puzzle solving, where experts and students use konstraint to experiment with modeling techniques and to compare solver strategies.

The project is maintained by an open-source community and has seen broad adoption in education and research contexts, contributing to tutorials, examples, and research on constraint solving.