This repository is for problem specifications written in Essence.

Each problem may contain a README file containing notes and findings about the problem. (Though most problems do not.)

Optionally, each problem may also contain:

• parameter and solution files for known/published instances.
• scripts to generate random parameter files.

See Directory structure for an explanation on how things are organised.

Old Version

An older version of the Essence Catalog is referenced from The Automated Modelling of Constraint Programs webpage hosted at the University of York. Unfortunately this version is not available at the moment. We found a version of it on the Wayback machine which can be used in case you need to refer to that version.

Relation to CSPLib

CSPLib is a library of problems specified in natural language. Its code is hosted at GitHub.

This repository uses CSPLib as a submodule.

We will try to make sure that:

• all the Essence files hosted on CSPLib are included in the Essence Catalog, and
• if an Essence file is added to the Essence Catalog, it will be moved to CSPLib as soon as possible (when we have a natural language problem specification ready).

Scripts

Some scripts are provided to keep the repository synchronised with CSPLib.

• Use scripts/export_to_csplib.sh for exporting Essence problem specification to the CSPLib submodule.
• Use scripts/import_from_csplib.sh for importing Essence problem specification from the CSPLib submodule.

EssenceCatalog-runs repository

See the EssenceCatalog-runs repository for generated Essence Prime models, and various runtime statistics.

Directory structure

• Essence files: problems/csplib-prob[number]-[essence]/[essence].essence.

  Where [problem] is the name of the problem, [number] is its CSPLib number and [essence] is the name of the problem specification in Essence.

• Essence parameter files: problems/csplib-prob[number]-[essence]/params.

• Where the problem is not available on CSPLib, the csplib-prob[number] part of the directory name will be dropped.

License

All files in this repository are licensed under Creative Commons Attribution 4.0 International License.