Theorem zfsteqd ≪ | index | src | ≫

theorem zfsteqd (_G: wff) (_n1 _n2: nat):
  $ _G -> _n1 = _n2 $ >
  $ _G -> zfst _n1 = zfst _n2 $;

Step	Hyp	Ref	Expression
1		hyp _nh	_G -> _n1 = _n2
2	1	appeq2d	_G -> case (\ mpos, mpos) (\ mneg, 0) @ _n1 = case (\ mpos, mpos) (\ mneg, 0) @ _n2
3	2	conv zfst	_G -> zfst _n1 = zfst _n2

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), axs_the (theid, the0), axs_peano (peano2, addeq, muleq)