[ library(fd) | Reference Manual | Alphabetic Index ]

# disjunction_choose(?Start1, +Duration1, ?Start2, +Duration2, ?Flag)

Flag indicates which of the two non-overlapping tasks is scheduled as first. Either the one with starting time Start1 and duration Duration1 (then the value of Flag is 1), or the second one with starting time Start2 and duration Duration2 (and the Flag is 2).
?Start1
A finite domain variable or integer
+Duration1
An integer
?Start2
A finite domain variable or integer
+Duration2
An integer
?Flag
A variable or integer

## Description

This constraint can be used, if there are two tasks that have to be scheduled on the same machine. It states which of the two tasks given by their starting times and durations is scheduled as first. It is activated whenever the maximum or minimum of domain variables Start1 or Start2 resp. changes or the Flag is set to an integer.

### Fail Conditions

Fails if there is no possibility to schedule given two tasks in any order under given conditions.

No.

### Exceptions

(4) instantiation fault
Duration1 or Duration2 is not instantiated.
(5) type error
Duration1 or Duration2 or Flag is instantiated but not an integer.

## Examples

```   [eclipse 5]: [X, Y]::1..10, disjunction_choose(X, 5, Y, 7, F).
X = X[1..10]
Y = Y[1..10]
F = F[1, 2]
Delayed goals:
disjunction_choose_1(X[1..10], 5, Y[1..10], 7, F[1, 2])
yes.
[eclipse 6]: [X, Y]::1..10, disjunction_choose(X, 5, Y, 7, 1).
X = X[1..5]
Y = Y[6..10]
Delayed goals:
Y[6..10] - X[1..5]#>=5
disjunction_choose_1(X[1..5], 5, Y[6..10], 7, 1)
yes.
[eclipse 8]: [X, Y]::1..5, disjunction_choose(X, 5, Y, 7, 2).
no (more) solution.

```