Theorem elssuni ≪ | index | src | ≫

theorem elssuni (A: set) (a: nat): $ a e. A -> a C_ sUnion A $;

Step	Hyp	Ref	Expression
1		elunii	a e. A -> a1 e. a -> a1 e. sUnion A
2	1	iald	a e. A -> A. a1 (a1 e. a -> a1 e. sUnion A)
3	2	conv subset	a e. A -> a C_ sUnion 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), axs_the (theid, the0), axs_peano (peano2, addeq, muleq)