# forbidStart

OPL constraint (scheduling) to limit the start of an interval variable.

context | type |
---|---|

Model files (.mod) |
boolean |

## Syntax

forbidStart(a, F); Where: dvar interval a; stepFunction F;

## Description

This constraint is used to indicate
that a given interval variable cannot start at a particular date.
Let *a* denote a fixed interval and *F* an integer stepwise
function. The constraint *forbidStart(a, F)*, states that whenever
the interval is present, it cannot start at a value *t* where *F(t)
= 0*.

Note: This constraint cannot be used in a meta-constraint.

## Example

The following constraint will prevent interval variable *a* to start in any interval [7i, 7i
+ 5) for **i** in [0, 51]:

stepFunction F = stepwise(i in 0..51, p in 0..1) { 100*p -> (7*i)+(5*p) ; 0 }; dvar interval a size 14; constraints { forbidStart(a, F); };