yields True if no subexpression in expr matches form, and yields False otherwise.

tests only those parts of expr on levels specified by levelspec.

represents an operator form of FreeQ that can be applied to an expression.

Details and OptionsDetails and Options

  • form can be a pattern.
  • FreeQ uses standard level specifications:
  • nlevels through n
    Infinitylevels through Infinity
    {n}level n only
    {n1,n2}levels through
  • The default value for levelspec in FreeQ is {0, Infinity}.
  • A positive level n consists of all parts of expr specified by n indices.
  • A negative level -n consists of all parts of expr with depth n.
  • Level consists of numbers, symbols and other objects that do not have subparts.
  • Level corresponds to the whole expression.
  • With the default option setting Heads->True, FreeQ looks at heads of expressions, and their parts.
  • FreeQ works on associations, testing values but not keys.
  • FreeQ[form][expr] is equivalent to FreeQ[expr,form].
Introduced in 1988
| Updated in 2014
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