Theorem writeeq3 ≪ | index | src | ≫ 

theorem writeeq3 (F: set) (a _b1 _b2: nat):
  $ _b1 = _b2 -> write F a _b1 == write F a _b2 $;
StepHypRefExpression
1 id 
_b1 = _b2 -> _b1 = _b2
2 1 writeeq3d 
_b1 = _b2 -> write F a _b1 == write 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)