| Step | Hyp | Ref | Expression | 
						
							| 1 |  | zriotaneg.1 | ⊢ ( 𝑥  =  - 𝑦  →  ( 𝜑  ↔  𝜓 ) ) | 
						
							| 2 |  | tru | ⊢ ⊤ | 
						
							| 3 |  | nfriota1 | ⊢ Ⅎ 𝑦 ( ℩ 𝑦  ∈  ℤ 𝜓 ) | 
						
							| 4 | 3 | nfneg | ⊢ Ⅎ 𝑦 - ( ℩ 𝑦  ∈  ℤ 𝜓 ) | 
						
							| 5 |  | znegcl | ⊢ ( 𝑦  ∈  ℤ  →  - 𝑦  ∈  ℤ ) | 
						
							| 6 | 5 | adantl | ⊢ ( ( ⊤  ∧  𝑦  ∈  ℤ )  →  - 𝑦  ∈  ℤ ) | 
						
							| 7 |  | simpr | ⊢ ( ( ⊤  ∧  ( ℩ 𝑦  ∈  ℤ 𝜓 )  ∈  ℤ )  →  ( ℩ 𝑦  ∈  ℤ 𝜓 )  ∈  ℤ ) | 
						
							| 8 | 7 | znegcld | ⊢ ( ( ⊤  ∧  ( ℩ 𝑦  ∈  ℤ 𝜓 )  ∈  ℤ )  →  - ( ℩ 𝑦  ∈  ℤ 𝜓 )  ∈  ℤ ) | 
						
							| 9 |  | negeq | ⊢ ( 𝑦  =  ( ℩ 𝑦  ∈  ℤ 𝜓 )  →  - 𝑦  =  - ( ℩ 𝑦  ∈  ℤ 𝜓 ) ) | 
						
							| 10 |  | znegcl | ⊢ ( 𝑥  ∈  ℤ  →  - 𝑥  ∈  ℤ ) | 
						
							| 11 |  | zcn | ⊢ ( 𝑥  ∈  ℤ  →  𝑥  ∈  ℂ ) | 
						
							| 12 |  | zcn | ⊢ ( 𝑦  ∈  ℤ  →  𝑦  ∈  ℂ ) | 
						
							| 13 |  | negcon2 | ⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  →  ( 𝑥  =  - 𝑦  ↔  𝑦  =  - 𝑥 ) ) | 
						
							| 14 | 11 12 13 | syl2an | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑦  ∈  ℤ )  →  ( 𝑥  =  - 𝑦  ↔  𝑦  =  - 𝑥 ) ) | 
						
							| 15 | 10 14 | reuhyp | ⊢ ( 𝑥  ∈  ℤ  →  ∃! 𝑦  ∈  ℤ 𝑥  =  - 𝑦 ) | 
						
							| 16 | 15 | adantl | ⊢ ( ( ⊤  ∧  𝑥  ∈  ℤ )  →  ∃! 𝑦  ∈  ℤ 𝑥  =  - 𝑦 ) | 
						
							| 17 | 4 6 8 1 9 16 | riotaxfrd | ⊢ ( ( ⊤  ∧  ∃! 𝑥  ∈  ℤ 𝜑 )  →  ( ℩ 𝑥  ∈  ℤ 𝜑 )  =  - ( ℩ 𝑦  ∈  ℤ 𝜓 ) ) | 
						
							| 18 | 2 17 | mpan | ⊢ ( ∃! 𝑥  ∈  ℤ 𝜑  →  ( ℩ 𝑥  ∈  ℤ 𝜑 )  =  - ( ℩ 𝑦  ∈  ℤ 𝜓 ) ) |