Armstrong Axiom

May 21, 2023

• Reflexivity rule. If α is a set of attributes and β ⊆ α, then α → β holds.
• Augmentation rule. If α → β holds and γ is a set of attributes, then γα → γβholds.
• Transitivity rule. If α → β holds and β → γ holds, then α → γ holds.
• Union rule. If α → β holds and α → γ holds, then α → βγ holds.
• Decomposition rule. If α → βγ holds, then α → β holds and α → γ holds.
• Pseudotransitivity rule. If α → β holds and γβ → δ holds, then αγ → δ holds.