Theorem sseli

Description: Membership implication from subclass relationship. (Contributed by NM, 5-Aug-1993)

	Ref	Expression
Hypothesis	sseli.1	$$⊢A\subseteq B$$
Assertion	sseli	$$⊢C\in A\to C\in B$$

Proof

Step	Hyp	Ref	Expression
1		sseli.1	$$⊢A\subseteq B$$
2		ssel	$$⊢A\subseteq B\to \left(C\in A\to C\in B\right)$$
3	1 2	ax-mp	$$⊢C\in A\to C\in B$$