| Step | Hyp | Ref | Expression | 
						
							| 1 |  | oppggic.o | ⊢ 𝑂  =  ( oppg ‘ 𝐺 ) | 
						
							| 2 |  | oppgcntz.z | ⊢ 𝑍  =  ( Cntz ‘ 𝐺 ) | 
						
							| 3 |  | eqcom | ⊢ ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 )  ↔  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 )  =  ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ) | 
						
							| 4 |  | eqid | ⊢ ( +g ‘ 𝐺 )  =  ( +g ‘ 𝐺 ) | 
						
							| 5 |  | eqid | ⊢ ( +g ‘ 𝑂 )  =  ( +g ‘ 𝑂 ) | 
						
							| 6 | 4 1 5 | oppgplus | ⊢ ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 ) | 
						
							| 7 | 4 1 5 | oppgplus | ⊢ ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 )  =  ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) | 
						
							| 8 | 6 7 | eqeq12i | ⊢ ( ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 )  ↔  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 )  =  ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 ) ) | 
						
							| 9 | 3 8 | bitr4i | ⊢ ( ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 )  ↔  ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 ) ) | 
						
							| 10 | 9 | ralbii | ⊢ ( ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 )  ↔  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 ) ) | 
						
							| 11 | 10 | anbi2i | ⊢ ( ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 ) )  ↔  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 ) ) ) | 
						
							| 12 | 11 | anbi2i | ⊢ ( ( 𝐴  ⊆  ( Base ‘ 𝐺 )  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 ) ) )  ↔  ( 𝐴  ⊆  ( Base ‘ 𝐺 )  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 ) ) ) ) | 
						
							| 13 |  | eqid | ⊢ ( Base ‘ 𝐺 )  =  ( Base ‘ 𝐺 ) | 
						
							| 14 | 13 2 | cntzrcl | ⊢ ( 𝑥  ∈  ( 𝑍 ‘ 𝐴 )  →  ( 𝐺  ∈  V  ∧  𝐴  ⊆  ( Base ‘ 𝐺 ) ) ) | 
						
							| 15 | 14 | simprd | ⊢ ( 𝑥  ∈  ( 𝑍 ‘ 𝐴 )  →  𝐴  ⊆  ( Base ‘ 𝐺 ) ) | 
						
							| 16 | 13 4 2 | elcntz | ⊢ ( 𝐴  ⊆  ( Base ‘ 𝐺 )  →  ( 𝑥  ∈  ( 𝑍 ‘ 𝐴 )  ↔  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 ) ) ) ) | 
						
							| 17 | 15 16 | biadanii | ⊢ ( 𝑥  ∈  ( 𝑍 ‘ 𝐴 )  ↔  ( 𝐴  ⊆  ( Base ‘ 𝐺 )  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝐺 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝐺 ) 𝑥 ) ) ) ) | 
						
							| 18 | 1 13 | oppgbas | ⊢ ( Base ‘ 𝐺 )  =  ( Base ‘ 𝑂 ) | 
						
							| 19 |  | eqid | ⊢ ( Cntz ‘ 𝑂 )  =  ( Cntz ‘ 𝑂 ) | 
						
							| 20 | 18 19 | cntzrcl | ⊢ ( 𝑥  ∈  ( ( Cntz ‘ 𝑂 ) ‘ 𝐴 )  →  ( 𝑂  ∈  V  ∧  𝐴  ⊆  ( Base ‘ 𝐺 ) ) ) | 
						
							| 21 | 20 | simprd | ⊢ ( 𝑥  ∈  ( ( Cntz ‘ 𝑂 ) ‘ 𝐴 )  →  𝐴  ⊆  ( Base ‘ 𝐺 ) ) | 
						
							| 22 | 18 5 19 | elcntz | ⊢ ( 𝐴  ⊆  ( Base ‘ 𝐺 )  →  ( 𝑥  ∈  ( ( Cntz ‘ 𝑂 ) ‘ 𝐴 )  ↔  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 ) ) ) ) | 
						
							| 23 | 21 22 | biadanii | ⊢ ( 𝑥  ∈  ( ( Cntz ‘ 𝑂 ) ‘ 𝐴 )  ↔  ( 𝐴  ⊆  ( Base ‘ 𝐺 )  ∧  ( 𝑥  ∈  ( Base ‘ 𝐺 )  ∧  ∀ 𝑦  ∈  𝐴 ( 𝑥 ( +g ‘ 𝑂 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑂 ) 𝑥 ) ) ) ) | 
						
							| 24 | 12 17 23 | 3bitr4i | ⊢ ( 𝑥  ∈  ( 𝑍 ‘ 𝐴 )  ↔  𝑥  ∈  ( ( Cntz ‘ 𝑂 ) ‘ 𝐴 ) ) | 
						
							| 25 | 24 | eqriv | ⊢ ( 𝑍 ‘ 𝐴 )  =  ( ( Cntz ‘ 𝑂 ) ‘ 𝐴 ) |