## `property::Null` -- the empty property

#### Introduction

If the combination of two properties is not possible, the ``empty property'' `property::Null` is returned as result.

#### Call(s)

`property::Null`

#### Related Functions

`assume`, `getprop`, `is`

#### Details

- The logical combination of two properties results in the ``empty'' or ``impossible'' property if the properties contradict each other.

#### Example 1

The property positive contradicts the property negative:

    >> Type::Positive and Type::Negative

                                  property::Null

The intersection of two intervals can be empty. The corresponding properties are derived to the empty property:

    >> Type::Interval(-1, 0) and Type::Interval(0, 1)

                                  property::Null

#### Changes

- new function

Do you have questions or comments?
Copyright © SciFace Software GmbH & Co. KG 2000