Theorem rexeqa ≪ | index | src | ≫ 

theorem rexeqa {x: nat} (p a b: wff x):
  $ p -> (a <-> b) $ >
  $ E. x (p /\ a) <-> E. x (p /\ b) $;
StepHypRefExpression
1 aneq2a 
(p -> (a <-> b)) -> (p /\ a <-> p /\ b)
2 hyp h 
p -> (a <-> b)
3 1, 2 ax_mp 
p /\ a <-> p /\ b
4 3 exeqi 
E. x (p /\ a) <-> E. x (p /\ b)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp), axs_pred_calc (ax_gen, ax_4)