- Origin
Inspired by [WallaceWilson06].
- Constraint
-
- Type
| |
- Arguments
| |
| |
| |
- Restrictions
-
- Purpose
is assigned to the item of the collection .
- Example
-
The constraint holds since is assigned to the second item of the
collection .
- Typical
|
|
|
- Symmetries
Items of and are permutable (same permutation used).
All occurrences of two distinct tuples of values in or can be swapped; all occurrences of a tuple of values in or can be renamed to any unused tuple of values.
- Usage
We consider an example taken fromΒ [WallaceWilson06]
were a customer has to decide among vacations.
There are two seasons when he can travel ( and )
and two locations and .
Furthermore assume that location is more important than season and the preferred period of the year
depends on the selected location.
The travel preferences of a customer are explicitly defined by stating the preferences ordering among
the possible tuples of values
,
,
and
.
For instance we may state within the preference table of the
constraint the preference ordering
,
which denotes the fact that our customer prefers in the and in the ,
and a vacation in is preferred over .
Finally a solution minimising the cost variable will match the preferences stated by our customer.
- See also
attached to cost variant:
Β ( parameter removed).
common keyword:
,
,
,
Β (preferences).
specialisation:
Β ( of replaced by single ).
- Keywords
characteristic of a constraint:
vector,
automaton,
automaton without counters,
reified automaton constraint.
constraint network structure:
Berge-acyclic constraint network.
constraint type:
order constraint.
filtering:
arc-consistency,
cost filtering constraint.
modelling:
preferences.
symmetry:
lexicographic order.