| Step | Hyp | Ref | Expression | 
						
							| 1 |  | maxidln1.1 | ⊢ 𝐻  =  ( 2nd  ‘ 𝑅 ) | 
						
							| 2 |  | maxidln1.2 | ⊢ 𝑈  =  ( GId ‘ 𝐻 ) | 
						
							| 3 |  | eqid | ⊢ ( 1st  ‘ 𝑅 )  =  ( 1st  ‘ 𝑅 ) | 
						
							| 4 |  | eqid | ⊢ ran  ( 1st  ‘ 𝑅 )  =  ran  ( 1st  ‘ 𝑅 ) | 
						
							| 5 | 3 4 | maxidlnr | ⊢ ( ( 𝑅  ∈  RingOps  ∧  𝑀  ∈  ( MaxIdl ‘ 𝑅 ) )  →  𝑀  ≠  ran  ( 1st  ‘ 𝑅 ) ) | 
						
							| 6 |  | maxidlidl | ⊢ ( ( 𝑅  ∈  RingOps  ∧  𝑀  ∈  ( MaxIdl ‘ 𝑅 ) )  →  𝑀  ∈  ( Idl ‘ 𝑅 ) ) | 
						
							| 7 | 3 1 4 2 | 1idl | ⊢ ( ( 𝑅  ∈  RingOps  ∧  𝑀  ∈  ( Idl ‘ 𝑅 ) )  →  ( 𝑈  ∈  𝑀  ↔  𝑀  =  ran  ( 1st  ‘ 𝑅 ) ) ) | 
						
							| 8 | 7 | necon3bbid | ⊢ ( ( 𝑅  ∈  RingOps  ∧  𝑀  ∈  ( Idl ‘ 𝑅 ) )  →  ( ¬  𝑈  ∈  𝑀  ↔  𝑀  ≠  ran  ( 1st  ‘ 𝑅 ) ) ) | 
						
							| 9 | 6 8 | syldan | ⊢ ( ( 𝑅  ∈  RingOps  ∧  𝑀  ∈  ( MaxIdl ‘ 𝑅 ) )  →  ( ¬  𝑈  ∈  𝑀  ↔  𝑀  ≠  ran  ( 1st  ‘ 𝑅 ) ) ) | 
						
							| 10 | 5 9 | mpbird | ⊢ ( ( 𝑅  ∈  RingOps  ∧  𝑀  ∈  ( MaxIdl ‘ 𝑅 ) )  →  ¬  𝑈  ∈  𝑀 ) |