How to prove "A->B,C then A->B and A->C" from Armstrong Axioms I know that this is true but I don't understand how to prove it.

The Problem:


  Prove or disprove that if A->B,C, then  A->B and A->C


This answer is similar but it does not prove the relation using Armstrong's axioms.
Just two steps: you can use reflexivity for B C -&gt; B and then transitivity from A -&gt; B C and the previous dependency. Analogous solution for the second case.