| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							rexuz3.1 | 
							⊢ 𝑍  =  ( ℤ≥ ‘ 𝑀 )  | 
						
						
							| 2 | 
							
								
							 | 
							eluzel2 | 
							⊢ ( 𝑗  ∈  ( ℤ≥ ‘ 𝑀 )  →  𝑀  ∈  ℤ )  | 
						
						
							| 3 | 
							
								2 1
							 | 
							eleq2s | 
							⊢ ( 𝑗  ∈  𝑍  →  𝑀  ∈  ℤ )  | 
						
						
							| 4 | 
							
								3
							 | 
							a1d | 
							⊢ ( 𝑗  ∈  𝑍  →  ( ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 )  →  𝑀  ∈  ℤ ) )  | 
						
						
							| 5 | 
							
								4
							 | 
							rexlimiv | 
							⊢ ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 )  →  𝑀  ∈  ℤ )  | 
						
						
							| 6 | 
							
								3
							 | 
							a1d | 
							⊢ ( 𝑗  ∈  𝑍  →  ( ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  →  𝑀  ∈  ℤ ) )  | 
						
						
							| 7 | 
							
								6
							 | 
							rexlimiv | 
							⊢ ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  →  𝑀  ∈  ℤ )  | 
						
						
							| 8 | 
							
								7
							 | 
							adantr | 
							⊢ ( ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ∧  ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 )  →  𝑀  ∈  ℤ )  | 
						
						
							| 9 | 
							
								1
							 | 
							rexuz3 | 
							⊢ ( 𝑀  ∈  ℤ  →  ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 )  ↔  ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 ) ) )  | 
						
						
							| 10 | 
							
								
							 | 
							rexanuz | 
							⊢ ( ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 )  ↔  ( ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ∧  ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 ) )  | 
						
						
							| 11 | 
							
								1
							 | 
							rexuz3 | 
							⊢ ( 𝑀  ∈  ℤ  →  ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ↔  ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑 ) )  | 
						
						
							| 12 | 
							
								1
							 | 
							rexuz3 | 
							⊢ ( 𝑀  ∈  ℤ  →  ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓  ↔  ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 ) )  | 
						
						
							| 13 | 
							
								11 12
							 | 
							anbi12d | 
							⊢ ( 𝑀  ∈  ℤ  →  ( ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ∧  ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 )  ↔  ( ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ∧  ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 ) ) )  | 
						
						
							| 14 | 
							
								10 13
							 | 
							bitr4id | 
							⊢ ( 𝑀  ∈  ℤ  →  ( ∃ 𝑗  ∈  ℤ ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 )  ↔  ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ∧  ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 ) ) )  | 
						
						
							| 15 | 
							
								9 14
							 | 
							bitrd | 
							⊢ ( 𝑀  ∈  ℤ  →  ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 )  ↔  ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ∧  ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 ) ) )  | 
						
						
							| 16 | 
							
								5 8 15
							 | 
							pm5.21nii | 
							⊢ ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) ( 𝜑  ∧  𝜓 )  ↔  ( ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜑  ∧  ∃ 𝑗  ∈  𝑍 ∀ 𝑘  ∈  ( ℤ≥ ‘ 𝑗 ) 𝜓 ) )  |