How can we prove the soundness of the Union rule via Armstrong’s Axioms

# Armstrong axioms

**Jaipreet_S**#2

**Union: if X → Y and X → Z then X → Y Z.**

*Proof: Using Armstrong’s Axioms:*

- X → Y , Given
- X → Z, Given
- X → XZ, Augment 2 by X
- XZ → Y Z, Augment 1 by Z
- X → Y Z, Transitivity using 3 and 4.