| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mndissubm.b | ⊢ 𝐵  =  ( Base ‘ 𝐺 ) | 
						
							| 2 |  | mndissubm.s | ⊢ 𝑆  =  ( Base ‘ 𝐻 ) | 
						
							| 3 |  | mndissubm.z | ⊢  0   =  ( 0g ‘ 𝐺 ) | 
						
							| 4 |  | simpr1 | ⊢ ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  →  𝑆  ⊆  𝐵 ) | 
						
							| 5 |  | simpr2 | ⊢ ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  →   0   ∈  𝑆 ) | 
						
							| 6 |  | mndmgm | ⊢ ( 𝐺  ∈  Mnd  →  𝐺  ∈  Mgm ) | 
						
							| 7 |  | mndmgm | ⊢ ( 𝐻  ∈  Mnd  →  𝐻  ∈  Mgm ) | 
						
							| 8 | 6 7 | anim12i | ⊢ ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  →  ( 𝐺  ∈  Mgm  ∧  𝐻  ∈  Mgm ) ) | 
						
							| 9 | 8 | ad2antrr | ⊢ ( ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  ∧  ( 𝑎  ∈  𝑆  ∧  𝑏  ∈  𝑆 ) )  →  ( 𝐺  ∈  Mgm  ∧  𝐻  ∈  Mgm ) ) | 
						
							| 10 |  | 3simpb | ⊢ ( ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) )  →  ( 𝑆  ⊆  𝐵  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) ) | 
						
							| 11 | 10 | ad2antlr | ⊢ ( ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  ∧  ( 𝑎  ∈  𝑆  ∧  𝑏  ∈  𝑆 ) )  →  ( 𝑆  ⊆  𝐵  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) ) | 
						
							| 12 |  | simpr | ⊢ ( ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  ∧  ( 𝑎  ∈  𝑆  ∧  𝑏  ∈  𝑆 ) )  →  ( 𝑎  ∈  𝑆  ∧  𝑏  ∈  𝑆 ) ) | 
						
							| 13 | 1 2 | mgmsscl | ⊢ ( ( ( 𝐺  ∈  Mgm  ∧  𝐻  ∈  Mgm )  ∧  ( 𝑆  ⊆  𝐵  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) )  ∧  ( 𝑎  ∈  𝑆  ∧  𝑏  ∈  𝑆 ) )  →  ( 𝑎 ( +g ‘ 𝐺 ) 𝑏 )  ∈  𝑆 ) | 
						
							| 14 | 9 11 12 13 | syl3anc | ⊢ ( ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  ∧  ( 𝑎  ∈  𝑆  ∧  𝑏  ∈  𝑆 ) )  →  ( 𝑎 ( +g ‘ 𝐺 ) 𝑏 )  ∈  𝑆 ) | 
						
							| 15 | 14 | ralrimivva | ⊢ ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  →  ∀ 𝑎  ∈  𝑆 ∀ 𝑏  ∈  𝑆 ( 𝑎 ( +g ‘ 𝐺 ) 𝑏 )  ∈  𝑆 ) | 
						
							| 16 |  | eqid | ⊢ ( +g ‘ 𝐺 )  =  ( +g ‘ 𝐺 ) | 
						
							| 17 | 1 3 16 | issubm | ⊢ ( 𝐺  ∈  Mnd  →  ( 𝑆  ∈  ( SubMnd ‘ 𝐺 )  ↔  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ∀ 𝑎  ∈  𝑆 ∀ 𝑏  ∈  𝑆 ( 𝑎 ( +g ‘ 𝐺 ) 𝑏 )  ∈  𝑆 ) ) ) | 
						
							| 18 | 17 | ad2antrr | ⊢ ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  →  ( 𝑆  ∈  ( SubMnd ‘ 𝐺 )  ↔  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ∀ 𝑎  ∈  𝑆 ∀ 𝑏  ∈  𝑆 ( 𝑎 ( +g ‘ 𝐺 ) 𝑏 )  ∈  𝑆 ) ) ) | 
						
							| 19 | 4 5 15 18 | mpbir3and | ⊢ ( ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  ∧  ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) ) )  →  𝑆  ∈  ( SubMnd ‘ 𝐺 ) ) | 
						
							| 20 | 19 | ex | ⊢ ( ( 𝐺  ∈  Mnd  ∧  𝐻  ∈  Mnd )  →  ( ( 𝑆  ⊆  𝐵  ∧   0   ∈  𝑆  ∧  ( +g ‘ 𝐻 )  =  ( ( +g ‘ 𝐺 )  ↾  ( 𝑆  ×  𝑆 ) ) )  →  𝑆  ∈  ( SubMnd ‘ 𝐺 ) ) ) |