Applies the quantified equation ∀x(e_l=e_r) to the left side of the equation tgt_l=tgt_r, leaving open the subgoal e_r σ = tgt_r.
Applies the quantified equation ∀x(e_l=e_r) to the left side of the equation tgt_l=tgt_r, leaving open the subgoal e_r σ = tgt_r.
Applies the quantified equation ∀x(e_l=e_r) to the right side of the equation tgt_l=tgt_r, leaving open the subgoal tgt_l = e_l σ.
Applies the quantified equation ∀x(e_l=e_r) to the right side of the equation tgt_l=tgt_r, leaving open the subgoal tgt_l = e_l σ.