Key takeaways
- Curriculum rules cover required periods, double periods, blocks, and spread preferences.
- Required lessons and some student-clash rules may be hard by policy.
- Spread and placement preferences usually belong in the soft set with penalties.
- Too many mandatory curriculum preferences can make the timetable infeasible.
Which curriculum rules affect placement?
The main curriculum placement rules are required periods per subject, double-period needs, parallel subject blocks, and spread or distribution preferences.
Required lessons decide what must be scheduled. Double periods and blocks decide which placements are acceptable. Spread preferences describe timetable quality and are often soft rather than hard.
Curriculum rules to classify
Classify each rule before generation.
- Required periods per subject
- Double-period needs
- Subject combinations taught in parallel as blocks
- Spread or distribution preferences
- Student-clash rules where local policy defines their status
- Room wishes or instructor time requests that may be preferences
How to classify curriculum rules
The aim is to avoid a model where every request is mandatory.
- List the rule and the subjects or groups it affects.
- Mark required lessons and non-negotiable clashes as hard where policy requires.
- Mark spread and distribution goals as soft unless policy makes them mandatory.
- Treat room wishes and instructor time requests as preferences unless they are true constraints.
- Check whether double periods and blocks leave enough possible placements.
- If the model is infeasible, relax soft rules before weakening hard rules.
Why blocks and double periods need care
Blocks link subjects that must be taught in parallel. Double periods require enough adjacent time. Both reduce the number of possible placements.
They may be necessary curriculum constraints, but they should be checked against teacher availability, room availability, and the teaching day. If too many placement preferences are added as hard rules, the model can become impossible.
Curriculum-rule review checklist
Before generation, confirm that required periods per subject are present, double-period needs are explicit, blocks are listed where subjects run in parallel, spread preferences are soft where appropriate, room wishes and instructor time requests are not hard by default, and student-clash rules match local policy.
How to avoid over-constraining curriculum rules
Over-constraining happens when preferences are treated as mandatory. Examples include making every instructor time request hard, banning theory in a specific last period as a hard rule, or turning room wishes into fixed requirements.
Use the hard set for rules that define feasibility. Use the soft set for preferences with penalties. Some teams also rank constraints as hard, firm, and soft so the solver or planner can relax lower-priority rules when the model is stuck.
Questions planners ask about curriculum rules
Are all curriculum rules hard?
No. Required lessons may be hard, while distribution or placement preferences can be soft. Some rules, such as student clashes, may be hard or soft by local policy.
What are curriculum blocks?
Blocks are subject combinations taught in parallel. They constrain placement because the linked subjects need compatible times.
Why do curriculum preferences cause infeasibility?
If preferences are marked mandatory, the model may have no solution. Rank rules as hard, firm, or soft where local practice supports that distinction.