| Step | Hyp | Ref | Expression | 
						
							| 1 |  | axdc4uz.1 | ⊢ 𝑀  ∈  ℤ | 
						
							| 2 |  | axdc4uz.2 | ⊢ 𝑍  =  ( ℤ≥ ‘ 𝑀 ) | 
						
							| 3 |  | eleq2 | ⊢ ( 𝑓  =  𝐴  →  ( 𝐶  ∈  𝑓  ↔  𝐶  ∈  𝐴 ) ) | 
						
							| 4 |  | xpeq2 | ⊢ ( 𝑓  =  𝐴  →  ( 𝑍  ×  𝑓 )  =  ( 𝑍  ×  𝐴 ) ) | 
						
							| 5 |  | pweq | ⊢ ( 𝑓  =  𝐴  →  𝒫  𝑓  =  𝒫  𝐴 ) | 
						
							| 6 | 5 | difeq1d | ⊢ ( 𝑓  =  𝐴  →  ( 𝒫  𝑓  ∖  { ∅ } )  =  ( 𝒫  𝐴  ∖  { ∅ } ) ) | 
						
							| 7 | 4 6 | feq23d | ⊢ ( 𝑓  =  𝐴  →  ( 𝐹 : ( 𝑍  ×  𝑓 ) ⟶ ( 𝒫  𝑓  ∖  { ∅ } )  ↔  𝐹 : ( 𝑍  ×  𝐴 ) ⟶ ( 𝒫  𝐴  ∖  { ∅ } ) ) ) | 
						
							| 8 | 3 7 | anbi12d | ⊢ ( 𝑓  =  𝐴  →  ( ( 𝐶  ∈  𝑓  ∧  𝐹 : ( 𝑍  ×  𝑓 ) ⟶ ( 𝒫  𝑓  ∖  { ∅ } ) )  ↔  ( 𝐶  ∈  𝐴  ∧  𝐹 : ( 𝑍  ×  𝐴 ) ⟶ ( 𝒫  𝐴  ∖  { ∅ } ) ) ) ) | 
						
							| 9 |  | feq3 | ⊢ ( 𝑓  =  𝐴  →  ( 𝑔 : 𝑍 ⟶ 𝑓  ↔  𝑔 : 𝑍 ⟶ 𝐴 ) ) | 
						
							| 10 | 9 | 3anbi1d | ⊢ ( 𝑓  =  𝐴  →  ( ( 𝑔 : 𝑍 ⟶ 𝑓  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) )  ↔  ( 𝑔 : 𝑍 ⟶ 𝐴  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) ) ) ) | 
						
							| 11 | 10 | exbidv | ⊢ ( 𝑓  =  𝐴  →  ( ∃ 𝑔 ( 𝑔 : 𝑍 ⟶ 𝑓  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) )  ↔  ∃ 𝑔 ( 𝑔 : 𝑍 ⟶ 𝐴  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) ) ) ) | 
						
							| 12 | 8 11 | imbi12d | ⊢ ( 𝑓  =  𝐴  →  ( ( ( 𝐶  ∈  𝑓  ∧  𝐹 : ( 𝑍  ×  𝑓 ) ⟶ ( 𝒫  𝑓  ∖  { ∅ } ) )  →  ∃ 𝑔 ( 𝑔 : 𝑍 ⟶ 𝑓  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) ) )  ↔  ( ( 𝐶  ∈  𝐴  ∧  𝐹 : ( 𝑍  ×  𝐴 ) ⟶ ( 𝒫  𝐴  ∖  { ∅ } ) )  →  ∃ 𝑔 ( 𝑔 : 𝑍 ⟶ 𝐴  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) ) ) ) ) | 
						
							| 13 |  | vex | ⊢ 𝑓  ∈  V | 
						
							| 14 |  | eqid | ⊢ ( rec ( ( 𝑦  ∈  V  ↦  ( 𝑦  +  1 ) ) ,  𝑀 )  ↾  ω )  =  ( rec ( ( 𝑦  ∈  V  ↦  ( 𝑦  +  1 ) ) ,  𝑀 )  ↾  ω ) | 
						
							| 15 |  | eqid | ⊢ ( 𝑛  ∈  ω ,  𝑥  ∈  𝑓  ↦  ( ( ( rec ( ( 𝑦  ∈  V  ↦  ( 𝑦  +  1 ) ) ,  𝑀 )  ↾  ω ) ‘ 𝑛 ) 𝐹 𝑥 ) )  =  ( 𝑛  ∈  ω ,  𝑥  ∈  𝑓  ↦  ( ( ( rec ( ( 𝑦  ∈  V  ↦  ( 𝑦  +  1 ) ) ,  𝑀 )  ↾  ω ) ‘ 𝑛 ) 𝐹 𝑥 ) ) | 
						
							| 16 | 1 2 13 14 15 | axdc4uzlem | ⊢ ( ( 𝐶  ∈  𝑓  ∧  𝐹 : ( 𝑍  ×  𝑓 ) ⟶ ( 𝒫  𝑓  ∖  { ∅ } ) )  →  ∃ 𝑔 ( 𝑔 : 𝑍 ⟶ 𝑓  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) ) ) | 
						
							| 17 | 12 16 | vtoclg | ⊢ ( 𝐴  ∈  𝑉  →  ( ( 𝐶  ∈  𝐴  ∧  𝐹 : ( 𝑍  ×  𝐴 ) ⟶ ( 𝒫  𝐴  ∖  { ∅ } ) )  →  ∃ 𝑔 ( 𝑔 : 𝑍 ⟶ 𝐴  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) ) ) ) | 
						
							| 18 | 17 | 3impib | ⊢ ( ( 𝐴  ∈  𝑉  ∧  𝐶  ∈  𝐴  ∧  𝐹 : ( 𝑍  ×  𝐴 ) ⟶ ( 𝒫  𝐴  ∖  { ∅ } ) )  →  ∃ 𝑔 ( 𝑔 : 𝑍 ⟶ 𝐴  ∧  ( 𝑔 ‘ 𝑀 )  =  𝐶  ∧  ∀ 𝑘  ∈  𝑍 ( 𝑔 ‘ ( 𝑘  +  1 ) )  ∈  ( 𝑘 𝐹 ( 𝑔 ‘ 𝑘 ) ) ) ) |