- Origin
Derived from .
- Constraint
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- Arguments
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- Restrictions
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- Purpose
Let us note the variables of the
collection.
is the period of the sequence
according to constraint . This means that
is the smallest natural number such that
holds for all .
- Example
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The constraint holds since, as
depicted by FigureΒ 5.320.1, its first argument
is equal (i.e.,Β since is set to ) to
the period of the sequence ; value 0 is
assumed to be equal to any other value.
- Typical
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- Symmetries
Items of can be reversed.
Items of can be shifted.
All occurrences of two distinct values of that are both different from 0 can be swapped; all occurrences of a value of that is different from 0 can be renamed to any unused value that is also different from 0.
- Arg. properties
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- Usage
Useful for timetabling problems where a person should repeat
some work pattern over an over except when he is unavailable
for some reason. The value 0 represents the fact that he is
unavailable, while the other values are used in the work pattern.
- Algorithm
SeeΒ [BeldiceanuPoder04].
- See also
hard version:
.
implied by:
.
- Keywords
characteristic of a constraint:
joker value.
combinatorial object:
periodic,
sequence.
constraint arguments:
pure functional dependency.
constraint type:
predefined constraint,
timetabling constraint,
scheduling constraint.
modelling:
functional dependency.