Theorem eqssr | index | src |

theorem eqssr (A B: set): $ A == B -> B C_ A $;
StepHypRefExpression
1 ssid
A C_ A
2 sseq1
A == B -> (A C_ A <-> B C_ A)
3 1, 2 mpbii
A == B -> B C_ A

Axiom use

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