Metamath Proof Explorer


Theorem idmgmhm

Description: The identity homomorphism on a magma. (Contributed by AV, 27-Feb-2020)

Ref Expression
Hypothesis idmgmhm.b ⊢ 𝐵 = ( Base ‘ 𝑀 )
Assertion idmgmhm ( 𝑀 ∈ Mgm → ( I ↾ 𝐵 ) ∈ ( 𝑀 MgmHom 𝑀 ) )

Proof

Step Hyp Ref Expression
1 idmgmhm.b ⊢ 𝐵 = ( Base ‘ 𝑀 )
2 id ⊢ ( 𝑀 ∈ Mgm → 𝑀 ∈ Mgm )
3 2 ancri ⊢ ( 𝑀 ∈ Mgm → ( 𝑀 ∈ Mgm ∧ 𝑀 ∈ Mgm ) )
4 f1oi ⊢ ( I ↾ 𝐵 ) : 𝐵 –1-1-onto→ 𝐵
5 f1of ⊢ ( ( I ↾ 𝐵 ) : 𝐵 –1-1-onto→ 𝐵 → ( I ↾ 𝐵 ) : 𝐵 ⟶ 𝐵 )
6 4 5 mp1i ⊢ ( 𝑀 ∈ Mgm → ( I ↾ 𝐵 ) : 𝐵 ⟶ 𝐵 )
7 eqid ⊢ ( +g ‘ 𝑀 ) = ( +g ‘ 𝑀 )
8 1 7 mgmcl ⊢ ( ( 𝑀 ∈ Mgm ∧ 𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵 ) → ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ∈ 𝐵 )
9 8 3expb ⊢ ( ( 𝑀 ∈ Mgm ∧ ( 𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵 ) ) → ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ∈ 𝐵 )
10 fvresi ⊢ ( ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ∈ 𝐵 → ( ( I ↾ 𝐵 ) ‘ ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ) = ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) )
11 9 10 syl ⊢ ( ( 𝑀 ∈ Mgm ∧ ( 𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵 ) ) → ( ( I ↾ 𝐵 ) ‘ ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ) = ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) )
12 fvresi ⊢ ( 𝑎 ∈ 𝐵 → ( ( I ↾ 𝐵 ) ‘ 𝑎 ) = 𝑎 )
13 fvresi ⊢ ( 𝑏 ∈ 𝐵 → ( ( I ↾ 𝐵 ) ‘ 𝑏 ) = 𝑏 )
14 12 13 oveqan12d ⊢ ( ( 𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵 ) → ( ( ( I ↾ 𝐵 ) ‘ 𝑎 ) ( +g ‘ 𝑀 ) ( ( I ↾ 𝐵 ) ‘ 𝑏 ) ) = ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) )
15 14 adantl ⊢ ( ( 𝑀 ∈ Mgm ∧ ( 𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵 ) ) → ( ( ( I ↾ 𝐵 ) ‘ 𝑎 ) ( +g ‘ 𝑀 ) ( ( I ↾ 𝐵 ) ‘ 𝑏 ) ) = ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) )
16 11 15 eqtr4d ⊢ ( ( 𝑀 ∈ Mgm ∧ ( 𝑎 ∈ 𝐵 ∧ 𝑏 ∈ 𝐵 ) ) → ( ( I ↾ 𝐵 ) ‘ ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ) = ( ( ( I ↾ 𝐵 ) ‘ 𝑎 ) ( +g ‘ 𝑀 ) ( ( I ↾ 𝐵 ) ‘ 𝑏 ) ) )
17 16 ralrimivva ⊢ ( 𝑀 ∈ Mgm → ∀ 𝑎 ∈ 𝐵 ∀ 𝑏 ∈ 𝐵 ( ( I ↾ 𝐵 ) ‘ ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ) = ( ( ( I ↾ 𝐵 ) ‘ 𝑎 ) ( +g ‘ 𝑀 ) ( ( I ↾ 𝐵 ) ‘ 𝑏 ) ) )
18 6 17 jca ⊢ ( 𝑀 ∈ Mgm → ( ( I ↾ 𝐵 ) : 𝐵 ⟶ 𝐵 ∧ ∀ 𝑎 ∈ 𝐵 ∀ 𝑏 ∈ 𝐵 ( ( I ↾ 𝐵 ) ‘ ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ) = ( ( ( I ↾ 𝐵 ) ‘ 𝑎 ) ( +g ‘ 𝑀 ) ( ( I ↾ 𝐵 ) ‘ 𝑏 ) ) ) )
19 1 1 7 7 ismgmhm ⊢ ( ( I ↾ 𝐵 ) ∈ ( 𝑀 MgmHom 𝑀 ) ↔ ( ( 𝑀 ∈ Mgm ∧ 𝑀 ∈ Mgm ) ∧ ( ( I ↾ 𝐵 ) : 𝐵 ⟶ 𝐵 ∧ ∀ 𝑎 ∈ 𝐵 ∀ 𝑏 ∈ 𝐵 ( ( I ↾ 𝐵 ) ‘ ( 𝑎 ( +g ‘ 𝑀 ) 𝑏 ) ) = ( ( ( I ↾ 𝐵 ) ‘ 𝑎 ) ( +g ‘ 𝑀 ) ( ( I ↾ 𝐵 ) ‘ 𝑏 ) ) ) ) )
20 3 18 19 sylanbrc ⊢ ( 𝑀 ∈ Mgm → ( I ↾ 𝐵 ) ∈ ( 𝑀 MgmHom 𝑀 ) )