Extraneous
- Removal from the left side: Attribute A is extraneous in α if A ∈ α and F logically implies (F − {α → β}) ∪ {(α − A) → β}.
- Removal from the right side: Attribute A is extraneous in β if A ∈ β and the set of functional dependencies (F − {α → β}) ∪ {α → (β − A)} logically implies F.