Metamath Proof Explorer


Theorem submss

Description: Submonoids are subsets of the base set. (Contributed by Mario Carneiro, 7-Mar-2015)

Ref Expression
Hypothesis submss.b ⊢ B = Base M
Assertion submss ⊢ S ∈ SubMnd ⁡ M → S ⊆ B

Proof

Step Hyp Ref Expression
1 submss.b ⊢ B = Base M
2 submrcl ⊢ S ∈ SubMnd ⁡ M → M ∈ Mnd
3 eqid ⊢ 0 M = 0 M
4 eqid ⊢ M ↾ 𝑠 S = M ↾ 𝑠 S
5 1 3 4 issubm2 ⊢ M ∈ Mnd → S ∈ SubMnd ⁡ M ↔ S ⊆ B ∧ 0 M ∈ S ∧ M ↾ 𝑠 S ∈ Mnd
6 2 5 syl ⊢ S ∈ SubMnd ⁡ M → S ∈ SubMnd ⁡ M ↔ S ⊆ B ∧ 0 M ∈ S ∧ M ↾ 𝑠 S ∈ Mnd
7 6 ibi ⊢ S ∈ SubMnd ⁡ M → S ⊆ B ∧ 0 M ∈ S ∧ M ↾ 𝑠 S ∈ Mnd
8 7 simp1d ⊢ S ∈ SubMnd ⁡ M → S ⊆ B