For sentences with exactly one free variable, this function denotes that variable. It is otherwise undefined.
(<=> (Satisfies-Constraint ?Object ?Constraint) (And (Object-Constraint ?Constraint) (Holds (Denotation (Listof 'Kappa (Listof (The-Free-Variable-In (Constraint.Expression ?Constraint))) (Constraint.Expression ?Constraint))) ?Object))) (<- (The-Free-Variable-In ?Sentence) (If (Sentence-With-One-Variable ?Sentence) (The ?Variable (Member ?Variable (Variables-In-Sentence ?Sentence)))))