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FreeQ[expr, form]
yields True if no subexpression in expr matches form, and yields False otherwise.
FreeQ[expr, form, levelspec]
tests only those parts of expr on levels specified by levelspec.
  • form can be a pattern.
  • FreeQ uses standard level specifications:
nlevels 1 through n
Infinitylevels 1 through Infinity
{n}level n only
{n1,n2}levels n1 through n2
  • 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 -1 consists of numbers, symbols and other objects that do not have subparts.
  • Level 0 corresponds to the whole expression.
  • With the default option setting Heads->True, FreeQ looks at heads of expressions, and their parts.
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