| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							bnj981.1 | 
							⊢ ( 𝜑  ↔  ( 𝑓 ‘ ∅ )  =   pred ( 𝑋 ,  𝐴 ,  𝑅 ) )  | 
						
						
							| 2 | 
							
								
							 | 
							bnj981.2 | 
							⊢ ( 𝜓  ↔  ∀ 𝑖  ∈  ω ( suc  𝑖  ∈  𝑛  →  ( 𝑓 ‘ suc  𝑖 )  =  ∪  𝑦  ∈  ( 𝑓 ‘ 𝑖 )  pred ( 𝑦 ,  𝐴 ,  𝑅 ) ) )  | 
						
						
							| 3 | 
							
								
							 | 
							bnj981.3 | 
							⊢ 𝐷  =  ( ω  ∖  { ∅ } )  | 
						
						
							| 4 | 
							
								
							 | 
							bnj981.4 | 
							⊢ 𝐵  =  { 𝑓  ∣  ∃ 𝑛  ∈  𝐷 ( 𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 ) }  | 
						
						
							| 5 | 
							
								
							 | 
							bnj981.5 | 
							⊢ ( 𝜒  ↔  ( 𝑛  ∈  𝐷  ∧  𝑓  Fn  𝑛  ∧  𝜑  ∧  𝜓 ) )  | 
						
						
							| 6 | 
							
								
							 | 
							nfv | 
							⊢ Ⅎ 𝑦 𝑍  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  | 
						
						
							| 7 | 
							
								
							 | 
							nfcv | 
							⊢ Ⅎ 𝑦 ω  | 
						
						
							| 8 | 
							
								
							 | 
							nfv | 
							⊢ Ⅎ 𝑦 suc  𝑖  ∈  𝑛  | 
						
						
							| 9 | 
							
								
							 | 
							nfiu1 | 
							⊢ Ⅎ 𝑦 ∪  𝑦  ∈  ( 𝑓 ‘ 𝑖 )  pred ( 𝑦 ,  𝐴 ,  𝑅 )  | 
						
						
							| 10 | 
							
								9
							 | 
							nfeq2 | 
							⊢ Ⅎ 𝑦 ( 𝑓 ‘ suc  𝑖 )  =  ∪  𝑦  ∈  ( 𝑓 ‘ 𝑖 )  pred ( 𝑦 ,  𝐴 ,  𝑅 )  | 
						
						
							| 11 | 
							
								8 10
							 | 
							nfim | 
							⊢ Ⅎ 𝑦 ( suc  𝑖  ∈  𝑛  →  ( 𝑓 ‘ suc  𝑖 )  =  ∪  𝑦  ∈  ( 𝑓 ‘ 𝑖 )  pred ( 𝑦 ,  𝐴 ,  𝑅 ) )  | 
						
						
							| 12 | 
							
								7 11
							 | 
							nfralw | 
							⊢ Ⅎ 𝑦 ∀ 𝑖  ∈  ω ( suc  𝑖  ∈  𝑛  →  ( 𝑓 ‘ suc  𝑖 )  =  ∪  𝑦  ∈  ( 𝑓 ‘ 𝑖 )  pred ( 𝑦 ,  𝐴 ,  𝑅 ) )  | 
						
						
							| 13 | 
							
								2 12
							 | 
							nfxfr | 
							⊢ Ⅎ 𝑦 𝜓  | 
						
						
							| 14 | 
							
								13
							 | 
							nf5ri | 
							⊢ ( 𝜓  →  ∀ 𝑦 𝜓 )  | 
						
						
							| 15 | 
							
								14 5
							 | 
							bnj1096 | 
							⊢ ( 𝜒  →  ∀ 𝑦 𝜒 )  | 
						
						
							| 16 | 
							
								15
							 | 
							nf5i | 
							⊢ Ⅎ 𝑦 𝜒  | 
						
						
							| 17 | 
							
								
							 | 
							nfv | 
							⊢ Ⅎ 𝑦 𝑖  ∈  𝑛  | 
						
						
							| 18 | 
							
								
							 | 
							nfv | 
							⊢ Ⅎ 𝑦 𝑍  ∈  ( 𝑓 ‘ 𝑖 )  | 
						
						
							| 19 | 
							
								16 17 18
							 | 
							nf3an | 
							⊢ Ⅎ 𝑦 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) )  | 
						
						
							| 20 | 
							
								19
							 | 
							nfex | 
							⊢ Ⅎ 𝑦 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) )  | 
						
						
							| 21 | 
							
								20
							 | 
							nfex | 
							⊢ Ⅎ 𝑦 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) )  | 
						
						
							| 22 | 
							
								21
							 | 
							nfex | 
							⊢ Ⅎ 𝑦 ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) )  | 
						
						
							| 23 | 
							
								6 22
							 | 
							nfim | 
							⊢ Ⅎ 𝑦 ( 𝑍  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  →  ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) ) )  | 
						
						
							| 24 | 
							
								
							 | 
							eleq1 | 
							⊢ ( 𝑦  =  𝑍  →  ( 𝑦  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  ↔  𝑍  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 ) ) )  | 
						
						
							| 25 | 
							
								
							 | 
							eleq1 | 
							⊢ ( 𝑦  =  𝑍  →  ( 𝑦  ∈  ( 𝑓 ‘ 𝑖 )  ↔  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) ) )  | 
						
						
							| 26 | 
							
								25
							 | 
							3anbi3d | 
							⊢ ( 𝑦  =  𝑍  →  ( ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑦  ∈  ( 𝑓 ‘ 𝑖 ) )  ↔  ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) ) ) )  | 
						
						
							| 27 | 
							
								26
							 | 
							3exbidv | 
							⊢ ( 𝑦  =  𝑍  →  ( ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑦  ∈  ( 𝑓 ‘ 𝑖 ) )  ↔  ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) ) ) )  | 
						
						
							| 28 | 
							
								24 27
							 | 
							imbi12d | 
							⊢ ( 𝑦  =  𝑍  →  ( ( 𝑦  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  →  ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑦  ∈  ( 𝑓 ‘ 𝑖 ) ) )  ↔  ( 𝑍  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  →  ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) ) ) ) )  | 
						
						
							| 29 | 
							
								1 2 3 4 5
							 | 
							bnj917 | 
							⊢ ( 𝑦  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  →  ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑦  ∈  ( 𝑓 ‘ 𝑖 ) ) )  | 
						
						
							| 30 | 
							
								23 28 29
							 | 
							vtoclg1f | 
							⊢ ( 𝑍  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  →  ( 𝑍  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  →  ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) ) ) )  | 
						
						
							| 31 | 
							
								30
							 | 
							pm2.43i | 
							⊢ ( 𝑍  ∈   trCl ( 𝑋 ,  𝐴 ,  𝑅 )  →  ∃ 𝑓 ∃ 𝑛 ∃ 𝑖 ( 𝜒  ∧  𝑖  ∈  𝑛  ∧  𝑍  ∈  ( 𝑓 ‘ 𝑖 ) ) )  |