Metamath Proof Explorer
		
		
		
		Description:  A positive integer is even or odd but not both.  (Contributed by NM, 1-Jan-2006)  (Revised by AV, 19-Jun-2020)
		
			
				
					|  |  | Ref | Expression | 
				
					|  | Assertion | nneoALTV | ⊢  ( 𝑁  ∈  ℕ  →  ( 𝑁  ∈   Even   ↔  ¬  𝑁  ∈   Odd  ) ) | 
			
		
		
			
				Proof
				
					
						| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nnz | ⊢ ( 𝑁  ∈  ℕ  →  𝑁  ∈  ℤ ) | 
						
							| 2 |  | zeo2ALTV | ⊢ ( 𝑁  ∈  ℤ  →  ( 𝑁  ∈   Even   ↔  ¬  𝑁  ∈   Odd  ) ) | 
						
							| 3 | 1 2 | syl | ⊢ ( 𝑁  ∈  ℕ  →  ( 𝑁  ∈   Even   ↔  ¬  𝑁  ∈   Odd  ) ) |