| Step | Hyp | Ref | Expression | 
						
							| 1 |  | cbvral6vw.1 | ⊢ ( 𝑥  =  𝑎  →  ( 𝜑  ↔  𝜒 ) ) | 
						
							| 2 |  | cbvral6vw.2 | ⊢ ( 𝑦  =  𝑏  →  ( 𝜒  ↔  𝜃 ) ) | 
						
							| 3 |  | cbvral6vw.3 | ⊢ ( 𝑧  =  𝑐  →  ( 𝜃  ↔  𝜏 ) ) | 
						
							| 4 |  | cbvral6vw.4 | ⊢ ( 𝑤  =  𝑑  →  ( 𝜏  ↔  𝜂 ) ) | 
						
							| 5 |  | cbvral6vw.5 | ⊢ ( 𝑝  =  𝑒  →  ( 𝜂  ↔  𝜁 ) ) | 
						
							| 6 |  | cbvral6vw.6 | ⊢ ( 𝑞  =  𝑓  →  ( 𝜁  ↔  𝜓 ) ) | 
						
							| 7 | 1 | 2ralbidv | ⊢ ( 𝑥  =  𝑎  →  ( ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜑  ↔  ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜒 ) ) | 
						
							| 8 | 2 | 2ralbidv | ⊢ ( 𝑦  =  𝑏  →  ( ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜒  ↔  ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜃 ) ) | 
						
							| 9 | 3 | 2ralbidv | ⊢ ( 𝑧  =  𝑐  →  ( ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜃  ↔  ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜏 ) ) | 
						
							| 10 | 4 | 2ralbidv | ⊢ ( 𝑤  =  𝑑  →  ( ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜏  ↔  ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜂 ) ) | 
						
							| 11 | 7 8 9 10 | cbvral4vw | ⊢ ( ∀ 𝑥  ∈  𝐴 ∀ 𝑦  ∈  𝐵 ∀ 𝑧  ∈  𝐶 ∀ 𝑤  ∈  𝐷 ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜑  ↔  ∀ 𝑎  ∈  𝐴 ∀ 𝑏  ∈  𝐵 ∀ 𝑐  ∈  𝐶 ∀ 𝑑  ∈  𝐷 ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜂 ) | 
						
							| 12 | 5 6 | cbvral2vw | ⊢ ( ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜂  ↔  ∀ 𝑒  ∈  𝐸 ∀ 𝑓  ∈  𝐹 𝜓 ) | 
						
							| 13 | 12 | 4ralbii | ⊢ ( ∀ 𝑎  ∈  𝐴 ∀ 𝑏  ∈  𝐵 ∀ 𝑐  ∈  𝐶 ∀ 𝑑  ∈  𝐷 ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜂  ↔  ∀ 𝑎  ∈  𝐴 ∀ 𝑏  ∈  𝐵 ∀ 𝑐  ∈  𝐶 ∀ 𝑑  ∈  𝐷 ∀ 𝑒  ∈  𝐸 ∀ 𝑓  ∈  𝐹 𝜓 ) | 
						
							| 14 | 11 13 | bitri | ⊢ ( ∀ 𝑥  ∈  𝐴 ∀ 𝑦  ∈  𝐵 ∀ 𝑧  ∈  𝐶 ∀ 𝑤  ∈  𝐷 ∀ 𝑝  ∈  𝐸 ∀ 𝑞  ∈  𝐹 𝜑  ↔  ∀ 𝑎  ∈  𝐴 ∀ 𝑏  ∈  𝐵 ∀ 𝑐  ∈  𝐶 ∀ 𝑑  ∈  𝐷 ∀ 𝑒  ∈  𝐸 ∀ 𝑓  ∈  𝐹 𝜓 ) |