Problems (Cops)

Database

Problem sets used in the competition stem from Cops, a database of confluence problems. Each problem has a unique and persistent number so that you can refer to the problems by e.g. "Cops ♯100". Each problem is equipped with tags, and problems can be queried using a combination of these tags.

Format

Every problem has one of the following formats. Follow the link to check the detail of each format.

• TRS format: This format specifies first-order term rewriting systems.
• CTRS format: This format specifies conditional term rewriting systems.
• HRS format: This format specifies higher-order rewrite systems.
• MSTRS format: This format specifies many-sorted term rewrite systems.

Submission

Submissions of new problems are welcome. For submission, please use the web interface. Problems should follow one of the formats above. Alternatively, you can send problem files in these formats to the steering committee.

Structure

Every problem belongs to one of the four families.

• literature: This family collects examples from the literature (articles, papers, technical notes, and so on) dealing with confluence.
• crafted: This family collects confluence problems which are crafted with pen and paper.
• generated: This family collects confluence problems which are derived by (automatic) transformation techniques, random generators, etc.
• debugging: This family collects problems where confluence analysis may not be of interest but which are suitable for debugging tools.