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rlfvarl – list of free variables

## Calling Sequence

rlfvarl \((\,\varphi\,)\)

## Arguments

\(\varphi\) | — | first-order formula |

## Returns

\(L\) | — | list of variables |

## Description

Returns the set of all variables that have a free occurrence in \(\varphi\) as a list. \(L\) is sorted according to the Reduce kernel order.

An *occurrence* of a variable is an occurrence inside an atomic formula.
A *free* occurrence is an occurrence outside the scope of a corresponding
quantifier. Note that by this definition, variables that are quantified but do
not appear in any atomic formulas do not occur at all.

## Example

```
rlfvarl(ex({w, x, y, z}, v=0 and x=0 and y=0) and w=0 and y=0);
```

## See Also