5.236. npair
| DESCRIPTION | LINKS | GRAPH |
- Origin
- Constraint
- Arguments
- Restrictions
- Purpose
is the number of distinct pairs of values assigned to the pairs of variables of the collection .
- Example
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The constraint holds since its first argument is set to the number of distinct pairs and of its second argument .
- Symmetries
Items of are permutable.
Attributes of are permutable w.r.t. permutation (permutation applied to all items).
All occurrences of two distinct tuples of values of can be swapped; all occurrences of a tuple of values of can be renamed to any unused tuple of values.
- Remark
This is an example of a number of distinct values constraint where there is more than one attribute that is associated with each vertex of the final graph.
- See also
related: Β ( of replaced by ), Β ( of replaced by ), Β ( of replaced by ).
specialisation: Β ( of replaced by ).
- Keywords
characteristic of a constraint: pair.
constraint type: counting constraint, value partitioning constraint.
final graph structure: strongly connected component, equivalence.
- Arc input(s)
- Arc generator
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- Arc arity
- Arc constraint(s)
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- Graph property(ies)
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- Graph model
PartsΒ (A) andΒ (B) of FigureΒ 5.236.1 respectively show the initial and final graph associated with the Example slot. Since we use the graph property we show the different strongly connected components of the final graph. Each strongly connected component corresponds to a pair of values that is assigned to some pairs of variables of the collection. In our example we have the following pairs of values: and .
Figure 5.236.1. Initial and final graph of the constraint
(a) (b)