Theorem birexrexa ≪ | index | src | ≫ 

theorem birexrexa {x y: nat} (q: wff y) (p: wff x) (a b: wff x y):
  $ p -> (a <-> E. y (q /\ b)) $ >
  $ E. x (p /\ a) <-> E. y (q /\ E. x (p /\ b)) $;
StepHypRefExpression
1 hyp h 
p -> (a <-> E. y (q /\ b))
2 1 birexan2a 
p /\ a <-> E. y (q /\ (p /\ b))
3 2 birexexi 
E. x (p /\ a) <-> E. y (q /\ E. x (p /\ b))

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp), axs_pred_calc (ax_gen, ax_4, ax_5, ax_11)