Theorem unidm | index | src |

theorem unidm (A: set): $ A u. A == A $;
StepHypRefExpression
1 equn2
A C_ A <-> A u. A == A
2 ssid
A C_ A
3 1, 2 mpbi
A u. A == 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)