| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ceqsex8v.1 | ⊢ 𝐴  ∈  V | 
						
							| 2 |  | ceqsex8v.2 | ⊢ 𝐵  ∈  V | 
						
							| 3 |  | ceqsex8v.3 | ⊢ 𝐶  ∈  V | 
						
							| 4 |  | ceqsex8v.4 | ⊢ 𝐷  ∈  V | 
						
							| 5 |  | ceqsex8v.5 | ⊢ 𝐸  ∈  V | 
						
							| 6 |  | ceqsex8v.6 | ⊢ 𝐹  ∈  V | 
						
							| 7 |  | ceqsex8v.7 | ⊢ 𝐺  ∈  V | 
						
							| 8 |  | ceqsex8v.8 | ⊢ 𝐻  ∈  V | 
						
							| 9 |  | ceqsex8v.9 | ⊢ ( 𝑥  =  𝐴  →  ( 𝜑  ↔  𝜓 ) ) | 
						
							| 10 |  | ceqsex8v.10 | ⊢ ( 𝑦  =  𝐵  →  ( 𝜓  ↔  𝜒 ) ) | 
						
							| 11 |  | ceqsex8v.11 | ⊢ ( 𝑧  =  𝐶  →  ( 𝜒  ↔  𝜃 ) ) | 
						
							| 12 |  | ceqsex8v.12 | ⊢ ( 𝑤  =  𝐷  →  ( 𝜃  ↔  𝜏 ) ) | 
						
							| 13 |  | ceqsex8v.13 | ⊢ ( 𝑣  =  𝐸  →  ( 𝜏  ↔  𝜂 ) ) | 
						
							| 14 |  | ceqsex8v.14 | ⊢ ( 𝑢  =  𝐹  →  ( 𝜂  ↔  𝜁 ) ) | 
						
							| 15 |  | ceqsex8v.15 | ⊢ ( 𝑡  =  𝐺  →  ( 𝜁  ↔  𝜎 ) ) | 
						
							| 16 |  | ceqsex8v.16 | ⊢ ( 𝑠  =  𝐻  →  ( 𝜎  ↔  𝜌 ) ) | 
						
							| 17 |  | 19.42vv | ⊢ ( ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) )  ↔  ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 18 | 17 | 2exbii | ⊢ ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) )  ↔  ∃ 𝑣 ∃ 𝑢 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 19 |  | 19.42vv | ⊢ ( ∃ 𝑣 ∃ 𝑢 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) )  ↔  ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 20 | 18 19 | bitri | ⊢ ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) )  ↔  ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 21 |  | 3anass | ⊢ ( ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 ) ) ) | 
						
							| 22 |  | df-3an | ⊢ ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 )  ↔  ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 ) ) | 
						
							| 23 | 22 | anbi2i | ⊢ ( ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) )  ↔  ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 ) ) ) | 
						
							| 24 | 21 23 | bitr4i | ⊢ ( ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 25 | 24 | 2exbii | ⊢ ( ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 26 | 25 | 2exbii | ⊢ ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 27 |  | df-3an | ⊢ ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) )  ↔  ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 28 | 20 26 27 | 3bitr4i | ⊢ ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 29 | 28 | 2exbii | ⊢ ( ∃ 𝑧 ∃ 𝑤 ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  ∃ 𝑧 ∃ 𝑤 ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 30 | 29 | 2exbii | ⊢ ( ∃ 𝑥 ∃ 𝑦 ∃ 𝑧 ∃ 𝑤 ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  ∃ 𝑥 ∃ 𝑦 ∃ 𝑧 ∃ 𝑤 ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) ) ) | 
						
							| 31 | 9 | 3anbi3d | ⊢ ( 𝑥  =  𝐴  →  ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 )  ↔  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜓 ) ) ) | 
						
							| 32 | 31 | 4exbidv | ⊢ ( 𝑥  =  𝐴  →  ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 )  ↔  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜓 ) ) ) | 
						
							| 33 | 10 | 3anbi3d | ⊢ ( 𝑦  =  𝐵  →  ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜓 )  ↔  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜒 ) ) ) | 
						
							| 34 | 33 | 4exbidv | ⊢ ( 𝑦  =  𝐵  →  ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜓 )  ↔  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜒 ) ) ) | 
						
							| 35 | 11 | 3anbi3d | ⊢ ( 𝑧  =  𝐶  →  ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜒 )  ↔  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜃 ) ) ) | 
						
							| 36 | 35 | 4exbidv | ⊢ ( 𝑧  =  𝐶  →  ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜒 )  ↔  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜃 ) ) ) | 
						
							| 37 | 12 | 3anbi3d | ⊢ ( 𝑤  =  𝐷  →  ( ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜃 )  ↔  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜏 ) ) ) | 
						
							| 38 | 37 | 4exbidv | ⊢ ( 𝑤  =  𝐷  →  ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜃 )  ↔  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜏 ) ) ) | 
						
							| 39 | 1 2 3 4 32 34 36 38 | ceqsex4v | ⊢ ( ∃ 𝑥 ∃ 𝑦 ∃ 𝑧 ∃ 𝑤 ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 )  ∧  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜑 ) )  ↔  ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜏 ) ) | 
						
							| 40 | 5 6 7 8 13 14 15 16 | ceqsex4v | ⊢ ( ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 )  ∧  𝜏 )  ↔  𝜌 ) | 
						
							| 41 | 30 39 40 | 3bitri | ⊢ ( ∃ 𝑥 ∃ 𝑦 ∃ 𝑧 ∃ 𝑤 ∃ 𝑣 ∃ 𝑢 ∃ 𝑡 ∃ 𝑠 ( ( ( 𝑥  =  𝐴  ∧  𝑦  =  𝐵 )  ∧  ( 𝑧  =  𝐶  ∧  𝑤  =  𝐷 ) )  ∧  ( ( 𝑣  =  𝐸  ∧  𝑢  =  𝐹 )  ∧  ( 𝑡  =  𝐺  ∧  𝑠  =  𝐻 ) )  ∧  𝜑 )  ↔  𝜌 ) |