Metamath Proof Explorer
		
		
		
		Description:  In a unitary ring, the ring unity is not a zero divisor.  (Contributed by AV, 7-Mar-2025)
		
			
				
					|  |  | Ref | Expression | 
					
						|  | Hypotheses | ringunitnzdiv.b | ⊢ 𝐵  =  ( Base ‘ 𝑅 ) | 
					
						|  |  | ringunitnzdiv.z | ⊢  0   =  ( 0g ‘ 𝑅 ) | 
					
						|  |  | ringunitnzdiv.t | ⊢  ·   =  ( .r ‘ 𝑅 ) | 
					
						|  |  | ringunitnzdiv.r | ⊢ ( 𝜑  →  𝑅  ∈  Ring ) | 
					
						|  |  | ringunitnzdiv.y | ⊢ ( 𝜑  →  𝑌  ∈  𝐵 ) | 
					
						|  |  | ring1nzdiv.x | ⊢  1   =  ( 1r ‘ 𝑅 ) | 
				
					|  | Assertion | ring1nzdiv | ⊢  ( 𝜑  →  ( (  1   ·  𝑌 )  =   0   ↔  𝑌  =   0  ) ) | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ringunitnzdiv.b | ⊢ 𝐵  =  ( Base ‘ 𝑅 ) | 
						
							| 2 |  | ringunitnzdiv.z | ⊢  0   =  ( 0g ‘ 𝑅 ) | 
						
							| 3 |  | ringunitnzdiv.t | ⊢  ·   =  ( .r ‘ 𝑅 ) | 
						
							| 4 |  | ringunitnzdiv.r | ⊢ ( 𝜑  →  𝑅  ∈  Ring ) | 
						
							| 5 |  | ringunitnzdiv.y | ⊢ ( 𝜑  →  𝑌  ∈  𝐵 ) | 
						
							| 6 |  | ring1nzdiv.x | ⊢  1   =  ( 1r ‘ 𝑅 ) | 
						
							| 7 |  | eqid | ⊢ ( Unit ‘ 𝑅 )  =  ( Unit ‘ 𝑅 ) | 
						
							| 8 | 7 6 | 1unit | ⊢ ( 𝑅  ∈  Ring  →   1   ∈  ( Unit ‘ 𝑅 ) ) | 
						
							| 9 | 4 8 | syl | ⊢ ( 𝜑  →   1   ∈  ( Unit ‘ 𝑅 ) ) | 
						
							| 10 | 1 2 3 4 5 9 | ringunitnzdiv | ⊢ ( 𝜑  →  ( (  1   ·  𝑌 )  =   0   ↔  𝑌  =   0  ) ) |