Theorem shsub2i

Description: Subspace sum is an upper bound of its arguments. (Contributed by NM, 17-Dec-2004) (New usage is discouraged.)

	Ref	Expression
Hypotheses	shincl.1	|- A e. SH
	shincl.2	|- B e. SH
Assertion	shsub2i	|- A C_ ( B +H A )

Proof

Step	Hyp	Ref	Expression
1		shincl.1	|- A e. SH
2		shincl.2	|- B e. SH
3	2 1	shsel2i	|- ( x e. A -> x e. ( B +H A ) )
4	3	ssriv	|- A C_ ( B +H A )