## `unassume` -- delete the properties of an identifier

#### Introduction

`unassume(`x`)` deletes the properties of the identifier `x`.

#### Call(s)

`unassume(x)`
`unassume( <Global>)`

#### Parameters

`x` | - | an identifier or a list or a set of identifiers

#### Options

`Global` | - | deletes the ``global property''

#### Returns

the void object `null()`.

#### Related Functions

`assume`, `delete`, `getprop`, `is`

#### Details

- `unassume` serves for deleting properties of identifiers set via `assume`. See `?property` for a short description of the property mechanism.
- If `x` is a list or a set of identifiers, then the properties of all specified identifiers are deleted.
- The calls `unassume(``)` and `unassume(`Global`)` are equivalent. This deletes the ``global property'' which is used for all identifiers. See `assume` for details on setting a global property.
- The command `delete x` deletes the value and the properties of the identifier `x`.

#### Example 1

Properties are attached to the identifiers `x` and `y`:

    >> assume(x > 0): assume(y < 0): getprop(x), getprop(y)

                                     > 0, < 0

    >> sign(x), sign(y)

                                       1, -1

`unassume` or `delete` deletes the properties:

    >> unassume(x): delete y: getprop(x), getprop(y)

                                       x, y

    >> sign(x), sign(y)

                                 sign(x), sign(y)

The properties of several identifiers can be deleted simultaneously by passing a list or a set to `unassume`:

    >> assume(x > y): unassume([x, y]): getprop(x), getprop(y)

                                       x, y

#### Example 2

All identifiers are assumed to represent real numbers. We set the corresponding global property:

    >> assume(Global, Type::Real): getprop(x), getprop(y), getprop(z)

                        Type::Real, Type::Real, Type::Real

    >> Re(x), Im(y), Re(x*y*z)

                                    x, 0, x y z

`unassume(``)` or `unassume(`Global`)` deletes the global property:

    >> unassume(): Re(x), Im(y), Re(x*y*z)

                              Re(x), Im(y), Re(x y z)

#### Changes

- A call without arguments deletes the global property.

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