Understanding Constraint Satisfaction in Timetable Generation
A clear guide for administrators on how mandatory rules and flexible preferences are evaluated to produce conflict-free timetables.
Auto Timetable Generator Team
Product & Engineering Team • June 12, 2026
School scheduling involves millions of possible permutations, making manual trial-and-error computationally impossible.
The engine separates non-negotiable Hard Constraints from flexible Soft Constraint optimization preferences.
Produces 100% mathematically valid master grids in seconds while maximizing teacher and student satisfaction.
1. Hard Constraints vs Soft Constraints
Auto Timetable Generator categorizes scheduling rules into two distinct enforcement levels:
Hard Constraints (Mandatory Rules): Rules that must be satisfied for a timetable to be valid. Examples include Teacher Non-Overlap, Room Non-Overlap, Teacher Consecutive Limits, and No Gaps for Students.
Soft Constraints (Optimization Preferences): Rules that the solver attempts to optimize for, but may relax if necessary to achieve a valid schedule. Examples include Spread Subjects Evenly, Balance Teacher Workload, Compress Teacher Days, and Room Stability.
Pro Tip: Hard constraints block invalid schedules, while soft constraints optimize overall schedule quality.
2. Supporting COHORT vs INDIVIDUAL Education Modes
Institutions operate under different structural scheduling models:
COHORT Mode: Designed for pre-packaged section schedules (common in primary and secondary schools), where student groups move together through fixed period blocks.
INDIVIDUAL Mode: Designed for elective-based models (common in higher education), where student schedules are generated around individual course registrations.
Pro Tip: Set your institution's default education mode on the Organization Settings Page.
3. Conflict-Free Algorithmic Placement
When you click Create Timetable on the Timetables Page, the solver engine initializes your active Term, Bell Schedule, and Course Sections. It evaluates available time slots against all active constraints, producing a conflict-free master grid.
Pro Tip: Inspect generated timetables on the Timetables Page using the Master Grid view.
Written by Auto Timetable Generator Team
Product & Engineering Team
Official recommendations and best practices from the Auto Timetable Generator academic team.
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