Theorem ssabi | index | src |

theorem ssabi {x: nat} (p q: wff x): $ p -> q $ > $ {x | p} C_ {x | q} $;
StepHypRefExpression
1 ssab
A. x (p -> q) <-> {x | p} C_ {x | q}
2 hyp h
p -> q
3 2 ax_gen
A. x (p -> q)
4 1, 3 mpbi
{x | p} C_ {x | q}

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)