Theorem shsel2i

Description: A subspace sum contains a member of one of its subspaces. (Contributed by NM, 19-Oct-1999) (New usage is discouraged.)

	Ref	Expression
Hypotheses	shincl.1	⊢ 𝐴 ∈ Sℋ
	shincl.2	⊢ 𝐵 ∈ Sℋ
Assertion	shsel2i	⊢ ( 𝐶 ∈ 𝐵 → 𝐶 ∈ ( 𝐴 +ℋ 𝐵 ) )

Proof

Step	Hyp	Ref	Expression
1		shincl.1	⊢ 𝐴 ∈ Sℋ
2		shincl.2	⊢ 𝐵 ∈ Sℋ
3		shsel2	⊢ ( ( 𝐴 ∈ Sℋ ∧ 𝐵 ∈ Sℋ ) → ( 𝐶 ∈ 𝐵 → 𝐶 ∈ ( 𝐴 +ℋ 𝐵 ) ) )
4	1 2 3	mp2an	⊢ ( 𝐶 ∈ 𝐵 → 𝐶 ∈ ( 𝐴 +ℋ 𝐵 ) )