unicode_fol_kit.free_variables

unicode_fol_kit.free_variables(node)[source]

Return the set of free Variable and LambdaVar occurrences in node.

The returned set is mixed: it may contain Variable objects (bound by Quantifier / SortedQuantifier) and LambdaVar objects (bound by Lambda). The two kinds are kept distinct so that a lambda binder over LambdaVar(“x”) never accidentally removes a logical Variable(“x”) from the free set.

Parameters:

node (Node)

Return type:

set