Theorem exral | index | src |

theorem exral {x y: nat} (a: wff y) (b: wff x y):
  $ E. x A. y (a -> b) -> A. y (a -> E. x b) $;
StepHypRefExpression
1 exal
E. x A. y (a -> b) -> A. y E. x (a -> b)
2 exim1
E. x (a -> b) -> a -> E. x b
3 2 alimi
A. y E. x (a -> b) -> A. y (a -> E. x b)
4 1, 3 rsyl
E. x A. y (a -> b) -> A. y (a -> E. x b)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp), axs_pred_calc (ax_gen, ax_4, ax_5, ax_6, ax_7, ax_10, ax_11, ax_12)