| Step | Hyp | Ref | Expression | 
						
							| 1 |  | txcmp.x | ⊢ 𝑋  =  ∪  𝑅 | 
						
							| 2 |  | txcmp.y | ⊢ 𝑌  =  ∪  𝑆 | 
						
							| 3 |  | txcmp.r | ⊢ ( 𝜑  →  𝑅  ∈  Comp ) | 
						
							| 4 |  | txcmp.s | ⊢ ( 𝜑  →  𝑆  ∈  Comp ) | 
						
							| 5 |  | txcmp.w | ⊢ ( 𝜑  →  𝑊  ⊆  ( 𝑅  ×t  𝑆 ) ) | 
						
							| 6 |  | txcmp.u | ⊢ ( 𝜑  →  ( 𝑋  ×  𝑌 )  =  ∪  𝑊 ) | 
						
							| 7 | 3 | adantr | ⊢ ( ( 𝜑  ∧  𝑥  ∈  𝑌 )  →  𝑅  ∈  Comp ) | 
						
							| 8 | 4 | adantr | ⊢ ( ( 𝜑  ∧  𝑥  ∈  𝑌 )  →  𝑆  ∈  Comp ) | 
						
							| 9 | 5 | adantr | ⊢ ( ( 𝜑  ∧  𝑥  ∈  𝑌 )  →  𝑊  ⊆  ( 𝑅  ×t  𝑆 ) ) | 
						
							| 10 | 6 | adantr | ⊢ ( ( 𝜑  ∧  𝑥  ∈  𝑌 )  →  ( 𝑋  ×  𝑌 )  =  ∪  𝑊 ) | 
						
							| 11 |  | simpr | ⊢ ( ( 𝜑  ∧  𝑥  ∈  𝑌 )  →  𝑥  ∈  𝑌 ) | 
						
							| 12 | 1 2 7 8 9 10 11 | txcmplem1 | ⊢ ( ( 𝜑  ∧  𝑥  ∈  𝑌 )  →  ∃ 𝑢  ∈  𝑆 ( 𝑥  ∈  𝑢  ∧  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑢 )  ⊆  ∪  𝑣 ) ) | 
						
							| 13 | 12 | ralrimiva | ⊢ ( 𝜑  →  ∀ 𝑥  ∈  𝑌 ∃ 𝑢  ∈  𝑆 ( 𝑥  ∈  𝑢  ∧  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑢 )  ⊆  ∪  𝑣 ) ) | 
						
							| 14 |  | unieq | ⊢ ( 𝑣  =  ( 𝑓 ‘ 𝑢 )  →  ∪  𝑣  =  ∪  ( 𝑓 ‘ 𝑢 ) ) | 
						
							| 15 | 14 | sseq2d | ⊢ ( 𝑣  =  ( 𝑓 ‘ 𝑢 )  →  ( ( 𝑋  ×  𝑢 )  ⊆  ∪  𝑣  ↔  ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) | 
						
							| 16 | 2 15 | cmpcovf | ⊢ ( ( 𝑆  ∈  Comp  ∧  ∀ 𝑥  ∈  𝑌 ∃ 𝑢  ∈  𝑆 ( 𝑥  ∈  𝑢  ∧  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑢 )  ⊆  ∪  𝑣 ) )  →  ∃ 𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) ( 𝑌  =  ∪  𝑤  ∧  ∃ 𝑓 ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) ) | 
						
							| 17 | 4 13 16 | syl2anc | ⊢ ( 𝜑  →  ∃ 𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) ( 𝑌  =  ∪  𝑤  ∧  ∃ 𝑓 ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) ) | 
						
							| 18 |  | simprrl | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin ) ) | 
						
							| 19 |  | ffn | ⊢ ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  →  𝑓  Fn  𝑤 ) | 
						
							| 20 |  | fniunfv | ⊢ ( 𝑓  Fn  𝑤  →  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  =  ∪  ran  𝑓 ) | 
						
							| 21 | 18 19 20 | 3syl | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  =  ∪  ran  𝑓 ) | 
						
							| 22 | 18 | frnd | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ran  𝑓  ⊆  ( 𝒫  𝑊  ∩  Fin ) ) | 
						
							| 23 |  | inss1 | ⊢ ( 𝒫  𝑊  ∩  Fin )  ⊆  𝒫  𝑊 | 
						
							| 24 | 22 23 | sstrdi | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ran  𝑓  ⊆  𝒫  𝑊 ) | 
						
							| 25 |  | sspwuni | ⊢ ( ran  𝑓  ⊆  𝒫  𝑊  ↔  ∪  ran  𝑓  ⊆  𝑊 ) | 
						
							| 26 | 24 25 | sylib | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  ran  𝑓  ⊆  𝑊 ) | 
						
							| 27 | 21 26 | eqsstrd | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ⊆  𝑊 ) | 
						
							| 28 |  | vex | ⊢ 𝑤  ∈  V | 
						
							| 29 |  | fvex | ⊢ ( 𝑓 ‘ 𝑧 )  ∈  V | 
						
							| 30 | 28 29 | iunex | ⊢ ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  V | 
						
							| 31 | 30 | elpw | ⊢ ( ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  𝒫  𝑊  ↔  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ⊆  𝑊 ) | 
						
							| 32 | 27 31 | sylibr | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  𝒫  𝑊 ) | 
						
							| 33 |  | inss2 | ⊢ ( 𝒫  𝑆  ∩  Fin )  ⊆  Fin | 
						
							| 34 |  | simplr | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) ) | 
						
							| 35 | 33 34 | sselid | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  𝑤  ∈  Fin ) | 
						
							| 36 |  | inss2 | ⊢ ( 𝒫  𝑊  ∩  Fin )  ⊆  Fin | 
						
							| 37 |  | fss | ⊢ ( ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ( 𝒫  𝑊  ∩  Fin )  ⊆  Fin )  →  𝑓 : 𝑤 ⟶ Fin ) | 
						
							| 38 | 18 36 37 | sylancl | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  𝑓 : 𝑤 ⟶ Fin ) | 
						
							| 39 |  | ffvelcdm | ⊢ ( ( 𝑓 : 𝑤 ⟶ Fin  ∧  𝑧  ∈  𝑤 )  →  ( 𝑓 ‘ 𝑧 )  ∈  Fin ) | 
						
							| 40 | 39 | ralrimiva | ⊢ ( 𝑓 : 𝑤 ⟶ Fin  →  ∀ 𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  Fin ) | 
						
							| 41 | 38 40 | syl | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∀ 𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  Fin ) | 
						
							| 42 |  | iunfi | ⊢ ( ( 𝑤  ∈  Fin  ∧  ∀ 𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  Fin )  →  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  Fin ) | 
						
							| 43 | 35 41 42 | syl2anc | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  Fin ) | 
						
							| 44 | 32 43 | elind | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  ( 𝒫  𝑊  ∩  Fin ) ) | 
						
							| 45 |  | simprl | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  𝑌  =  ∪  𝑤 ) | 
						
							| 46 |  | uniiun | ⊢ ∪  𝑤  =  ∪  𝑧  ∈  𝑤 𝑧 | 
						
							| 47 | 45 46 | eqtrdi | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  𝑌  =  ∪  𝑧  ∈  𝑤 𝑧 ) | 
						
							| 48 | 47 | xpeq2d | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ( 𝑋  ×  𝑌 )  =  ( 𝑋  ×  ∪  𝑧  ∈  𝑤 𝑧 ) ) | 
						
							| 49 |  | xpiundi | ⊢ ( 𝑋  ×  ∪  𝑧  ∈  𝑤 𝑧 )  =  ∪  𝑧  ∈  𝑤 ( 𝑋  ×  𝑧 ) | 
						
							| 50 | 48 49 | eqtrdi | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ( 𝑋  ×  𝑌 )  =  ∪  𝑧  ∈  𝑤 ( 𝑋  ×  𝑧 ) ) | 
						
							| 51 |  | simprrr | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) | 
						
							| 52 |  | xpeq2 | ⊢ ( 𝑢  =  𝑧  →  ( 𝑋  ×  𝑢 )  =  ( 𝑋  ×  𝑧 ) ) | 
						
							| 53 |  | fveq2 | ⊢ ( 𝑢  =  𝑧  →  ( 𝑓 ‘ 𝑢 )  =  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 54 | 53 | unieqd | ⊢ ( 𝑢  =  𝑧  →  ∪  ( 𝑓 ‘ 𝑢 )  =  ∪  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 55 | 52 54 | sseq12d | ⊢ ( 𝑢  =  𝑧  →  ( ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 )  ↔  ( 𝑋  ×  𝑧 )  ⊆  ∪  ( 𝑓 ‘ 𝑧 ) ) ) | 
						
							| 56 | 55 | cbvralvw | ⊢ ( ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 )  ↔  ∀ 𝑧  ∈  𝑤 ( 𝑋  ×  𝑧 )  ⊆  ∪  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 57 | 51 56 | sylib | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∀ 𝑧  ∈  𝑤 ( 𝑋  ×  𝑧 )  ⊆  ∪  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 58 |  | ss2iun | ⊢ ( ∀ 𝑧  ∈  𝑤 ( 𝑋  ×  𝑧 )  ⊆  ∪  ( 𝑓 ‘ 𝑧 )  →  ∪  𝑧  ∈  𝑤 ( 𝑋  ×  𝑧 )  ⊆  ∪  𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 59 | 57 58 | syl | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  𝑧  ∈  𝑤 ( 𝑋  ×  𝑧 )  ⊆  ∪  𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 60 | 50 59 | eqsstrd | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ( 𝑋  ×  𝑌 )  ⊆  ∪  𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 61 | 18 | ffvelcdmda | ⊢ ( ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  ∧  𝑧  ∈  𝑤 )  →  ( 𝑓 ‘ 𝑧 )  ∈  ( 𝒫  𝑊  ∩  Fin ) ) | 
						
							| 62 | 23 61 | sselid | ⊢ ( ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  ∧  𝑧  ∈  𝑤 )  →  ( 𝑓 ‘ 𝑧 )  ∈  𝒫  𝑊 ) | 
						
							| 63 |  | elpwi | ⊢ ( ( 𝑓 ‘ 𝑧 )  ∈  𝒫  𝑊  →  ( 𝑓 ‘ 𝑧 )  ⊆  𝑊 ) | 
						
							| 64 |  | uniss | ⊢ ( ( 𝑓 ‘ 𝑧 )  ⊆  𝑊  →  ∪  ( 𝑓 ‘ 𝑧 )  ⊆  ∪  𝑊 ) | 
						
							| 65 | 62 63 64 | 3syl | ⊢ ( ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  ∧  𝑧  ∈  𝑤 )  →  ∪  ( 𝑓 ‘ 𝑧 )  ⊆  ∪  𝑊 ) | 
						
							| 66 | 6 | ad3antrrr | ⊢ ( ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  ∧  𝑧  ∈  𝑤 )  →  ( 𝑋  ×  𝑌 )  =  ∪  𝑊 ) | 
						
							| 67 | 65 66 | sseqtrrd | ⊢ ( ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  ∧  𝑧  ∈  𝑤 )  →  ∪  ( 𝑓 ‘ 𝑧 )  ⊆  ( 𝑋  ×  𝑌 ) ) | 
						
							| 68 | 67 | ralrimiva | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∀ 𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 )  ⊆  ( 𝑋  ×  𝑌 ) ) | 
						
							| 69 |  | iunss | ⊢ ( ∪  𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 )  ⊆  ( 𝑋  ×  𝑌 )  ↔  ∀ 𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 )  ⊆  ( 𝑋  ×  𝑌 ) ) | 
						
							| 70 | 68 69 | sylibr | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∪  𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 )  ⊆  ( 𝑋  ×  𝑌 ) ) | 
						
							| 71 | 60 70 | eqssd | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ( 𝑋  ×  𝑌 )  =  ∪  𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 72 |  | iuncom4 | ⊢ ∪  𝑧  ∈  𝑤 ∪  ( 𝑓 ‘ 𝑧 )  =  ∪  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 ) | 
						
							| 73 | 71 72 | eqtrdi | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ( 𝑋  ×  𝑌 )  =  ∪  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 74 |  | unieq | ⊢ ( 𝑣  =  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  →  ∪  𝑣  =  ∪  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 ) ) | 
						
							| 75 | 74 | rspceeqv | ⊢ ( ( ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 )  ∈  ( 𝒫  𝑊  ∩  Fin )  ∧  ( 𝑋  ×  𝑌 )  =  ∪  ∪  𝑧  ∈  𝑤 ( 𝑓 ‘ 𝑧 ) )  →  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑌 )  =  ∪  𝑣 ) | 
						
							| 76 | 44 73 75 | syl2anc | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  ( 𝑌  =  ∪  𝑤  ∧  ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) ) )  →  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑌 )  =  ∪  𝑣 ) | 
						
							| 77 | 76 | expr | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  𝑌  =  ∪  𝑤 )  →  ( ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) )  →  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑌 )  =  ∪  𝑣 ) ) | 
						
							| 78 | 77 | exlimdv | ⊢ ( ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  ∧  𝑌  =  ∪  𝑤 )  →  ( ∃ 𝑓 ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) )  →  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑌 )  =  ∪  𝑣 ) ) | 
						
							| 79 | 78 | expimpd | ⊢ ( ( 𝜑  ∧  𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) )  →  ( ( 𝑌  =  ∪  𝑤  ∧  ∃ 𝑓 ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) )  →  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑌 )  =  ∪  𝑣 ) ) | 
						
							| 80 | 79 | rexlimdva | ⊢ ( 𝜑  →  ( ∃ 𝑤  ∈  ( 𝒫  𝑆  ∩  Fin ) ( 𝑌  =  ∪  𝑤  ∧  ∃ 𝑓 ( 𝑓 : 𝑤 ⟶ ( 𝒫  𝑊  ∩  Fin )  ∧  ∀ 𝑢  ∈  𝑤 ( 𝑋  ×  𝑢 )  ⊆  ∪  ( 𝑓 ‘ 𝑢 ) ) )  →  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑌 )  =  ∪  𝑣 ) ) | 
						
							| 81 | 17 80 | mpd | ⊢ ( 𝜑  →  ∃ 𝑣  ∈  ( 𝒫  𝑊  ∩  Fin ) ( 𝑋  ×  𝑌 )  =  ∪  𝑣 ) |