Hard constraints are rules that must be satisfied for a schedule to be valid.
​Even if one hard constraint cannot be satisfied, the scheduling problem becomes infeasible, meaning no valid schedule can be generated.

This constraint defines how many staff members must be assigned to each shift.

Oplist must assign staff in a way that satisfies the defined staffing requirements for every shift. These requirements may include total staff requirements as well as group-based requirements.

These requirements are defined at the department level and apply only to the schedules generated for that specific department.

When total staff requirements are defined using Min / Max values, the scheduling algorithm prioritizes reaching the maximum value whenever possible.

Group-based requirements can also be defined using Min / Max or Exact values. However, unlike total staff requirements, the algorithm does not actively try to reach the maximum value for groups. The maximum value is used only as an upper limit.

In cases where all scheduling constraints cannot be satisfied simultaneously, limited flexibility may be applied only to the total staff requirement. This flexibility allows the requirement to be relaxed by one staff member below the defined minimum or exact value.

This relaxation can be applied independently for each shift on each day. In other words, every shift instance may be relaxed by at most one staff member, but it cannot be relaxed further. Different shifts may each use this flexibility separately.

However, group-based staffing requirements are always strictly enforced and cannot be relaxed.

If the staffing requirements of a shift cannot be satisfied together with other scheduling constraints, the scheduling problem becomes infeasible.

➡️ Learn more: How Are Shift Requirements Defined?

This constraint defines which shifts can or cannot be assigned to a staff member on the day following a completed shift.

These rules are defined at the Global Shifts level and apply to all departments where the shift is used.

During schedule generation, Oplist must ensure that all post-shift restrictions are satisfied. If an assignment would violate a post-shift rule, the assignment is considered invalid and cannot be used in the schedule.

For example, a rule may prevent a staff member who worked a Night Shift from being assigned to certain shifts on the following day, or from being scheduled at all on that day.

When these rules are active, the scheduling algorithm automatically evaluates the shift worked on the previous day and prevents assignments that violate the defined restrictions.

Post-shift rules cannot be relaxed. If the required staffing levels and other constraints cannot be satisfied while respecting these rules, the scheduling problem becomes infeasible.

➡️ Learn more: Post-Shift Assignment Rules

This constraint prevents specific staff members from being assigned to certain shifts.

If the staffing requirements of a shift cannot be satisfied because of these exclusions, the scheduling problem becomes infeasible.

➡️ Learn more: Exclude Staff from a Shift

This constraint defines minimum and maximum working hour limits for staff members within a given time period.

These limits can be configured on a weekly or monthly basis and are treated as hard constraints during schedule generation.

Working hours are calculated based on:

During scheduling, Oplist must ensure that a staff member’s total working hours remain within the defined limits.

If assigning a shift would cause a staff member’s working hours to exceed the maximum limit or fall below the required minimum within the planning period, the assignment cannot be made.

If the scheduling problem cannot satisfy these limits together with other constraints, the schedule becomes infeasible.

➡️ Learn more: Working Hour Limits

This constraint limits how many consecutive days a staff member can work without a rest day.

The maximum number of consecutive working days is defined as a hard constraint and must be satisfied during schedule generation.

Oplist ensures that a staff member is not assigned to more consecutive working days than the defined limit.

If this constraint cannot be satisfied together with other scheduling requirements, the scheduling problem becomes infeasible.

➡️ Learn more: Maximum Consecutive Working Days

This constraint limits how many times a specific shift can be assigned within a given time period.

These limits are treated as hard constraints and must be satisfied during schedule generation.

Example

Oplist ensures that the number of assignments for a shift does not exceed the defined limit within the specified period.

If the scheduling requirements or other constraints require assigning the shift beyond the defined limit, the scheduling problem becomes infeasible.

➡️ Learn more: Limit Shift Assignments per Period

This constraint defines required or forbidden assignments for specific staff members.

These constraints can be added manually in the schedule generation screen using Add New Assignment or Exclude Staff Shifts.

Examples include:

All manually added assignments and exclusions are treated as hard constraints.

If they cannot be satisfied together with other scheduling constraints, the scheduling problem becomes infeasible.

➡️ Learn more: Add New Assignment and Exclude Staff Shifts

Leave days represent planned staff leave defined in the system.

These entries are treated as hard constraints.

When a staff member has leave on a specific day, they are excluded from shift assignments for that day.

Leave may represent different types of time off, such as rest days or paid leave, and some leave types may contribute to working hour calculations depending on their configuration.

If the number of available staff after leave entries is insufficient to satisfy shift requirements, the scheduling problem may become infeasible.

➡️ Learn more: HR Planning – Adding Special Requests and Leave

Special requests represent staff scheduling preferences.

These may include:

Oplist attempts to satisfy these requests whenever possible, but they are not mandatory.

If fulfilling a request would conflict with hard constraints or prevent a valid schedule from being generated, the request may be ignored.

➡️ Learn more: HR Planning – Adding Special Requests and Leave