Theorem nfsab1 | index | src |

theorem nfsab1 {x: nat} (A: set x): $ FS/ x S\ x, A $;
StepHypRefExpression
1 nfsbs1
FS/ x S[fst a1 / x] A
2 1 nfel2
F/ x snd a1 e. S[fst a1 / x] A
3 2 nfab
FS/ x {a1 | snd a1 e. S[fst a1 / x] A}
4 3 conv sab
FS/ x S\ x, A

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)