Theorem funceq3 ≪ | index | src | ≫ 

theorem funceq3 (F A _B1 _B2: set):
  $ _B1 == _B2 -> (func F A _B1 <-> func F A _B2) $;
StepHypRefExpression
1 id 
_B1 == _B2 -> _B1 == _B2
2 1 funceq3d 
_B1 == _B2 -> (func F A _B1 <-> func F A _B2)

Axiom use

axs_prop_calc (ax_1, ax_2, ax_3, ax_mp, itru), axs_pred_calc (ax_gen, ax_4, ax_5, ax_6, ax_7, ax_10, ax_11, ax_12), axs_set (elab, ax_8)