| Step | Hyp | Ref | Expression | 
						
							| 1 |  | vtocl3gaf.a | ⊢ Ⅎ 𝑥 𝐴 | 
						
							| 2 |  | vtocl3gaf.b | ⊢ Ⅎ 𝑦 𝐴 | 
						
							| 3 |  | vtocl3gaf.c | ⊢ Ⅎ 𝑧 𝐴 | 
						
							| 4 |  | vtocl3gaf.d | ⊢ Ⅎ 𝑦 𝐵 | 
						
							| 5 |  | vtocl3gaf.e | ⊢ Ⅎ 𝑧 𝐵 | 
						
							| 6 |  | vtocl3gaf.f | ⊢ Ⅎ 𝑧 𝐶 | 
						
							| 7 |  | vtocl3gaf.1 | ⊢ Ⅎ 𝑥 𝜓 | 
						
							| 8 |  | vtocl3gaf.2 | ⊢ Ⅎ 𝑦 𝜒 | 
						
							| 9 |  | vtocl3gaf.3 | ⊢ Ⅎ 𝑧 𝜃 | 
						
							| 10 |  | vtocl3gaf.4 | ⊢ ( 𝑥  =  𝐴  →  ( 𝜑  ↔  𝜓 ) ) | 
						
							| 11 |  | vtocl3gaf.5 | ⊢ ( 𝑦  =  𝐵  →  ( 𝜓  ↔  𝜒 ) ) | 
						
							| 12 |  | vtocl3gaf.6 | ⊢ ( 𝑧  =  𝐶  →  ( 𝜒  ↔  𝜃 ) ) | 
						
							| 13 |  | vtocl3gaf.7 | ⊢ ( ( 𝑥  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜑 ) | 
						
							| 14 | 1 | nfel1 | ⊢ Ⅎ 𝑥 𝐴  ∈  𝑅 | 
						
							| 15 |  | nfv | ⊢ Ⅎ 𝑥 𝑦  ∈  𝑆 | 
						
							| 16 |  | nfv | ⊢ Ⅎ 𝑥 𝑧  ∈  𝑇 | 
						
							| 17 | 14 15 16 | nf3an | ⊢ Ⅎ 𝑥 ( 𝐴  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 ) | 
						
							| 18 | 17 7 | nfim | ⊢ Ⅎ 𝑥 ( ( 𝐴  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜓 ) | 
						
							| 19 | 2 | nfel1 | ⊢ Ⅎ 𝑦 𝐴  ∈  𝑅 | 
						
							| 20 | 4 | nfel1 | ⊢ Ⅎ 𝑦 𝐵  ∈  𝑆 | 
						
							| 21 |  | nfv | ⊢ Ⅎ 𝑦 𝑧  ∈  𝑇 | 
						
							| 22 | 19 20 21 | nf3an | ⊢ Ⅎ 𝑦 ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝑧  ∈  𝑇 ) | 
						
							| 23 | 22 8 | nfim | ⊢ Ⅎ 𝑦 ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜒 ) | 
						
							| 24 | 3 | nfel1 | ⊢ Ⅎ 𝑧 𝐴  ∈  𝑅 | 
						
							| 25 | 5 | nfel1 | ⊢ Ⅎ 𝑧 𝐵  ∈  𝑆 | 
						
							| 26 | 6 | nfel1 | ⊢ Ⅎ 𝑧 𝐶  ∈  𝑇 | 
						
							| 27 | 24 25 26 | nf3an | ⊢ Ⅎ 𝑧 ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝐶  ∈  𝑇 ) | 
						
							| 28 | 27 9 | nfim | ⊢ Ⅎ 𝑧 ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝐶  ∈  𝑇 )  →  𝜃 ) | 
						
							| 29 |  | eleq1 | ⊢ ( 𝑥  =  𝐴  →  ( 𝑥  ∈  𝑅  ↔  𝐴  ∈  𝑅 ) ) | 
						
							| 30 | 29 | 3anbi1d | ⊢ ( 𝑥  =  𝐴  →  ( ( 𝑥  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  ↔  ( 𝐴  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 ) ) ) | 
						
							| 31 | 30 10 | imbi12d | ⊢ ( 𝑥  =  𝐴  →  ( ( ( 𝑥  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜑 )  ↔  ( ( 𝐴  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜓 ) ) ) | 
						
							| 32 |  | eleq1 | ⊢ ( 𝑦  =  𝐵  →  ( 𝑦  ∈  𝑆  ↔  𝐵  ∈  𝑆 ) ) | 
						
							| 33 | 32 | 3anbi2d | ⊢ ( 𝑦  =  𝐵  →  ( ( 𝐴  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  ↔  ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝑧  ∈  𝑇 ) ) ) | 
						
							| 34 | 33 11 | imbi12d | ⊢ ( 𝑦  =  𝐵  →  ( ( ( 𝐴  ∈  𝑅  ∧  𝑦  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜓 )  ↔  ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜒 ) ) ) | 
						
							| 35 |  | eleq1 | ⊢ ( 𝑧  =  𝐶  →  ( 𝑧  ∈  𝑇  ↔  𝐶  ∈  𝑇 ) ) | 
						
							| 36 | 35 | 3anbi3d | ⊢ ( 𝑧  =  𝐶  →  ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  ↔  ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝐶  ∈  𝑇 ) ) ) | 
						
							| 37 | 36 12 | imbi12d | ⊢ ( 𝑧  =  𝐶  →  ( ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝑧  ∈  𝑇 )  →  𝜒 )  ↔  ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝐶  ∈  𝑇 )  →  𝜃 ) ) ) | 
						
							| 38 | 1 2 3 4 5 6 18 23 28 31 34 37 13 | vtocl3gf | ⊢ ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝐶  ∈  𝑇 )  →  ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝐶  ∈  𝑇 )  →  𝜃 ) ) | 
						
							| 39 | 38 | pm2.43i | ⊢ ( ( 𝐴  ∈  𝑅  ∧  𝐵  ∈  𝑆  ∧  𝐶  ∈  𝑇 )  →  𝜃 ) |