startBeforeStart
OPL constraint (scheduling) to restrict the relative positions of interval variables.
| context | type |
|---|---|
| Model files (.mod) |
boolean |
Syntax
startBeforeStart (a,b[,z]); Where: dexpr int z; dvar interval a; dvar interval b;
Description
This constraint states that the start of a given interval variable a (modified by an optional time value z) is less than or equal to the start of a given interval variable b: s(a) + z ≤ s(b).
If one or both of the interval variables of the precedence constraint is absent, then the precedence is systematically considered to be true and, thus, it does not impact the schedule.
Note: This constraint cannot be
used in a meta-constraint.
Example
The following precedence constraint states that the start of interval c plus 5 time units is less than or equal to the start of interval d.
startBeforeStart(c,d,5);