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Ordered Variable List
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The domain OrderedVariableList provides symbols which are restricted
to a particular list and have a definite ordering. Those two features
are specified by a List Symbol object that is the argument to the
domain.

This is a sample ordering of three symbols. ::

  ls:List Symbol:=['x,'a,'z]
    [x,a,z]
                                Type: List Symbol

Let's build the domain ::

  Z:=OVAR ls
    OrderedVariableList [x,a,z]
                                Type: Domain

How many variables does it have? ::

  size()$Z
    3
                                Type: NonNegativeInteger

They are (in the imposed order) ::

  lv:=[index(i::PI)$Z for i in 1..size()$Z]
    [x,a,z]
                                Type: List OrderedVariableList [x,a,z]

Check that the ordering is right ::

  sorted?(>,lv)
    true
                                Type: Boolean

See Also:

* )show OrderedVariableList