| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							bnj580.1 | 
							⊢ ( 𝜑  ↔  ( 𝑓 ‘ ∅ )  =   pred ( 𝑥 ,  𝐴 ,  𝑅 ) )  | 
						
						
							| 2 | 
							
								
							 | 
							bnj580.2 | 
							⊢ ( 𝜓  ↔  ∀ 𝑖  ∈  ω ( suc  𝑖  ∈  𝑛  →  ( 𝑓 ‘ suc  𝑖 )  =  ∪  𝑦  ∈  ( 𝑓 ‘ 𝑖 )  pred ( 𝑦 ,  𝐴 ,  𝑅 ) ) )  | 
						
						
							| 3 | 
							
								
							 | 
							bnj580.3 | 
							⊢ ( 𝜒  ↔  ( 𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 ) )  | 
						
						
							| 4 | 
							
								
							 | 
							bnj580.4 | 
							⊢ ( 𝜑′  ↔  [ 𝑔  /  𝑓 ] 𝜑 )  | 
						
						
							| 5 | 
							
								
							 | 
							bnj580.5 | 
							⊢ ( 𝜓′  ↔  [ 𝑔  /  𝑓 ] 𝜓 )  | 
						
						
							| 6 | 
							
								
							 | 
							bnj580.6 | 
							⊢ ( 𝜒′  ↔  [ 𝑔  /  𝑓 ] 𝜒 )  | 
						
						
							| 7 | 
							
								
							 | 
							bnj580.7 | 
							⊢ 𝐷  =  ( ω  ∖  { ∅ } )  | 
						
						
							| 8 | 
							
								
							 | 
							bnj580.8 | 
							⊢ ( 𝜃  ↔  ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) )  | 
						
						
							| 9 | 
							
								
							 | 
							bnj580.9 | 
							⊢ ( 𝜏  ↔  ∀ 𝑘  ∈  𝑛 ( 𝑘  E  𝑗  →  [ 𝑘  /  𝑗 ] 𝜃 ) )  | 
						
						
							| 10 | 
							
								3
							 | 
							simp1bi | 
							⊢ ( 𝜒  →  𝑓  Fn  𝑛 )  | 
						
						
							| 11 | 
							
								3 4 5 6
							 | 
							bnj581 | 
							⊢ ( 𝜒′  ↔  ( 𝑔  Fn  𝑛  ∧  𝜑′  ∧  𝜓′ ) )  | 
						
						
							| 12 | 
							
								11
							 | 
							simp1bi | 
							⊢ ( 𝜒′  →  𝑔  Fn  𝑛 )  | 
						
						
							| 13 | 
							
								10 12
							 | 
							bnj240 | 
							⊢ ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓  Fn  𝑛  ∧  𝑔  Fn  𝑛 ) )  | 
						
						
							| 14 | 
							
								4 1
							 | 
							bnj154 | 
							⊢ ( 𝜑′  ↔  ( 𝑔 ‘ ∅ )  =   pred ( 𝑥 ,  𝐴 ,  𝑅 ) )  | 
						
						
							| 15 | 
							
								
							 | 
							vex | 
							⊢ 𝑔  ∈  V  | 
						
						
							| 16 | 
							
								2 5 15
							 | 
							bnj540 | 
							⊢ ( 𝜓′  ↔  ∀ 𝑖  ∈  ω ( suc  𝑖  ∈  𝑛  →  ( 𝑔 ‘ suc  𝑖 )  =  ∪  𝑦  ∈  ( 𝑔 ‘ 𝑖 )  pred ( 𝑦 ,  𝐴 ,  𝑅 ) ) )  | 
						
						
							| 17 | 
							
								8
							 | 
							bnj591 | 
							⊢ ( [ 𝑘  /  𝑗 ] 𝜃  ↔  ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑘 )  =  ( 𝑔 ‘ 𝑘 ) ) )  | 
						
						
							| 18 | 
							
								1 2 3 7 14 16 11 8 17 9
							 | 
							bnj594 | 
							⊢ ( ( 𝑗  ∈  𝑛  ∧  𝜏 )  →  𝜃 )  | 
						
						
							| 19 | 
							
								18
							 | 
							ex | 
							⊢ ( 𝑗  ∈  𝑛  →  ( 𝜏  →  𝜃 ) )  | 
						
						
							| 20 | 
							
								19
							 | 
							rgen | 
							⊢ ∀ 𝑗  ∈  𝑛 ( 𝜏  →  𝜃 )  | 
						
						
							| 21 | 
							
								
							 | 
							vex | 
							⊢ 𝑛  ∈  V  | 
						
						
							| 22 | 
							
								21 9
							 | 
							bnj110 | 
							⊢ ( (  E   Fr  𝑛  ∧  ∀ 𝑗  ∈  𝑛 ( 𝜏  →  𝜃 ) )  →  ∀ 𝑗  ∈  𝑛 𝜃 )  | 
						
						
							| 23 | 
							
								20 22
							 | 
							mpan2 | 
							⊢ (  E   Fr  𝑛  →  ∀ 𝑗  ∈  𝑛 𝜃 )  | 
						
						
							| 24 | 
							
								8
							 | 
							ralbii | 
							⊢ ( ∀ 𝑗  ∈  𝑛 𝜃  ↔  ∀ 𝑗  ∈  𝑛 ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) )  | 
						
						
							| 25 | 
							
								23 24
							 | 
							sylib | 
							⊢ (  E   Fr  𝑛  →  ∀ 𝑗  ∈  𝑛 ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) )  | 
						
						
							| 26 | 
							
								25
							 | 
							r19.21be | 
							⊢ ∀ 𝑗  ∈  𝑛 (  E   Fr  𝑛  →  ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) )  | 
						
						
							| 27 | 
							
								7
							 | 
							bnj923 | 
							⊢ ( 𝑛  ∈  𝐷  →  𝑛  ∈  ω )  | 
						
						
							| 28 | 
							
								
							 | 
							nnord | 
							⊢ ( 𝑛  ∈  ω  →  Ord  𝑛 )  | 
						
						
							| 29 | 
							
								
							 | 
							ordfr | 
							⊢ ( Ord  𝑛  →   E   Fr  𝑛 )  | 
						
						
							| 30 | 
							
								27 28 29
							 | 
							3syl | 
							⊢ ( 𝑛  ∈  𝐷  →   E   Fr  𝑛 )  | 
						
						
							| 31 | 
							
								30
							 | 
							3ad2ant1 | 
							⊢ ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →   E   Fr  𝑛 )  | 
						
						
							| 32 | 
							
								31
							 | 
							pm4.71ri | 
							⊢ ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  ↔  (  E   Fr  𝑛  ∧  ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ ) ) )  | 
						
						
							| 33 | 
							
								32
							 | 
							imbi1i | 
							⊢ ( ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) )  ↔  ( (  E   Fr  𝑛  ∧  ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ ) )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) )  | 
						
						
							| 34 | 
							
								
							 | 
							impexp | 
							⊢ ( ( (  E   Fr  𝑛  ∧  ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ ) )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) )  ↔  (  E   Fr  𝑛  →  ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) ) )  | 
						
						
							| 35 | 
							
								33 34
							 | 
							bitri | 
							⊢ ( ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) )  ↔  (  E   Fr  𝑛  →  ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) ) )  | 
						
						
							| 36 | 
							
								35
							 | 
							ralbii | 
							⊢ ( ∀ 𝑗  ∈  𝑛 ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) )  ↔  ∀ 𝑗  ∈  𝑛 (  E   Fr  𝑛  →  ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) ) )  | 
						
						
							| 37 | 
							
								26 36
							 | 
							mpbir | 
							⊢ ∀ 𝑗  ∈  𝑛 ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) )  | 
						
						
							| 38 | 
							
								
							 | 
							r19.21v | 
							⊢ ( ∀ 𝑗  ∈  𝑛 ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) )  ↔  ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ∀ 𝑗  ∈  𝑛 ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) )  | 
						
						
							| 39 | 
							
								37 38
							 | 
							mpbi | 
							⊢ ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  ∀ 𝑗  ∈  𝑛 ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) )  | 
						
						
							| 40 | 
							
								
							 | 
							eqfnfv | 
							⊢ ( ( 𝑓  Fn  𝑛  ∧  𝑔  Fn  𝑛 )  →  ( 𝑓  =  𝑔  ↔  ∀ 𝑗  ∈  𝑛 ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 ) ) )  | 
						
						
							| 41 | 
							
								40
							 | 
							biimprd | 
							⊢ ( ( 𝑓  Fn  𝑛  ∧  𝑔  Fn  𝑛 )  →  ( ∀ 𝑗  ∈  𝑛 ( 𝑓 ‘ 𝑗 )  =  ( 𝑔 ‘ 𝑗 )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 42 | 
							
								13 39 41
							 | 
							sylc | 
							⊢ ( ( 𝑛  ∈  𝐷  ∧  𝜒  ∧  𝜒′ )  →  𝑓  =  𝑔 )  | 
						
						
							| 43 | 
							
								42
							 | 
							3expib | 
							⊢ ( 𝑛  ∈  𝐷  →  ( ( 𝜒  ∧  𝜒′ )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 44 | 
							
								43
							 | 
							alrimivv | 
							⊢ ( 𝑛  ∈  𝐷  →  ∀ 𝑓 ∀ 𝑔 ( ( 𝜒  ∧  𝜒′ )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 45 | 
							
								
							 | 
							sbsbc | 
							⊢ ( [ 𝑔  /  𝑓 ] 𝜒  ↔  [ 𝑔  /  𝑓 ] 𝜒 )  | 
						
						
							| 46 | 
							
								45
							 | 
							anbi2i | 
							⊢ ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  ↔  ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 ) )  | 
						
						
							| 47 | 
							
								46
							 | 
							imbi1i | 
							⊢ ( ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  →  𝑓  =  𝑔 )  ↔  ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 48 | 
							
								47
							 | 
							2albii | 
							⊢ ( ∀ 𝑓 ∀ 𝑔 ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  →  𝑓  =  𝑔 )  ↔  ∀ 𝑓 ∀ 𝑔 ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 49 | 
							
								
							 | 
							nfv | 
							⊢ Ⅎ 𝑔 𝜒  | 
						
						
							| 50 | 
							
								49
							 | 
							mo3 | 
							⊢ ( ∃* 𝑓 𝜒  ↔  ∀ 𝑓 ∀ 𝑔 ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 51 | 
							
								6
							 | 
							anbi2i | 
							⊢ ( ( 𝜒  ∧  𝜒′ )  ↔  ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 ) )  | 
						
						
							| 52 | 
							
								51
							 | 
							imbi1i | 
							⊢ ( ( ( 𝜒  ∧  𝜒′ )  →  𝑓  =  𝑔 )  ↔  ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 53 | 
							
								52
							 | 
							2albii | 
							⊢ ( ∀ 𝑓 ∀ 𝑔 ( ( 𝜒  ∧  𝜒′ )  →  𝑓  =  𝑔 )  ↔  ∀ 𝑓 ∀ 𝑔 ( ( 𝜒  ∧  [ 𝑔  /  𝑓 ] 𝜒 )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 54 | 
							
								48 50 53
							 | 
							3bitr4i | 
							⊢ ( ∃* 𝑓 𝜒  ↔  ∀ 𝑓 ∀ 𝑔 ( ( 𝜒  ∧  𝜒′ )  →  𝑓  =  𝑔 ) )  | 
						
						
							| 55 | 
							
								44 54
							 | 
							sylibr | 
							⊢ ( 𝑛  ∈  𝐷  →  ∃* 𝑓 𝜒 )  |