I'm trying to understand this classical Sequent Calculus proof.
These are the rules Of Sequent Calculus(version 1) in respect to this question
How do we know to use [v R2] and [v R1] instead of [v L] which I originally used
and also on why we know to use [v R2] on A⊢(A→B) ∨ (B→A) and [v R1] on ¬A⊢(A→B) ∨ (B→A) and not the other way around.