| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							fin23lem.a | 
							⊢ 𝑈  =  seqω ( ( 𝑖  ∈  ω ,  𝑢  ∈  V  ↦  if ( ( ( 𝑡 ‘ 𝑖 )  ∩  𝑢 )  =  ∅ ,  𝑢 ,  ( ( 𝑡 ‘ 𝑖 )  ∩  𝑢 ) ) ) ,  ∪  ran  𝑡 )  | 
						
						
							| 2 | 
							
								
							 | 
							fin23lem17.f | 
							⊢ 𝐹  =  { 𝑔  ∣  ∀ 𝑎  ∈  ( 𝒫  𝑔  ↑m  ω ) ( ∀ 𝑥  ∈  ω ( 𝑎 ‘ suc  𝑥 )  ⊆  ( 𝑎 ‘ 𝑥 )  →  ∩  ran  𝑎  ∈  ran  𝑎 ) }  | 
						
						
							| 3 | 
							
								
							 | 
							fin23lem.b | 
							⊢ 𝑃  =  { 𝑣  ∈  ω  ∣  ∩  ran  𝑈  ⊆  ( 𝑡 ‘ 𝑣 ) }  | 
						
						
							| 4 | 
							
								
							 | 
							fin23lem.c | 
							⊢ 𝑄  =  ( 𝑤  ∈  ω  ↦  ( ℩ 𝑥  ∈  𝑃 ( 𝑥  ∩  𝑃 )  ≈  𝑤 ) )  | 
						
						
							| 5 | 
							
								
							 | 
							fin23lem.d | 
							⊢ 𝑅  =  ( 𝑤  ∈  ω  ↦  ( ℩ 𝑥  ∈  ( ω  ∖  𝑃 ) ( 𝑥  ∩  ( ω  ∖  𝑃 ) )  ≈  𝑤 ) )  | 
						
						
							| 6 | 
							
								
							 | 
							fin23lem.e | 
							⊢ 𝑍  =  if ( 𝑃  ∈  Fin ,  ( 𝑡  ∘  𝑅 ) ,  ( ( 𝑧  ∈  𝑃  ↦  ( ( 𝑡 ‘ 𝑧 )  ∖  ∩  ran  𝑈 ) )  ∘  𝑄 ) )  | 
						
						
							| 7 | 
							
								2
							 | 
							ssfin3ds | 
							⊢ ( ( 𝐺  ∈  𝐹  ∧  ∪  ran  𝑡  ⊆  𝐺 )  →  ∪  ran  𝑡  ∈  𝐹 )  | 
						
						
							| 8 | 
							
								1 2 3 4 5 6
							 | 
							fin23lem29 | 
							⊢ ∪  ran  𝑍  ⊆  ∪  ran  𝑡  | 
						
						
							| 9 | 
							
								8
							 | 
							a1i | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ∪  ran  𝑍  ⊆  ∪  ran  𝑡 )  | 
						
						
							| 10 | 
							
								1 2
							 | 
							fin23lem21 | 
							⊢ ( ( ∪  ran  𝑡  ∈  𝐹  ∧  𝑡 : ω –1-1→ 𝑉 )  →  ∩  ran  𝑈  ≠  ∅ )  | 
						
						
							| 11 | 
							
								10
							 | 
							ancoms | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ∩  ran  𝑈  ≠  ∅ )  | 
						
						
							| 12 | 
							
								
							 | 
							n0 | 
							⊢ ( ∩  ran  𝑈  ≠  ∅  ↔  ∃ 𝑎 𝑎  ∈  ∩  ran  𝑈 )  | 
						
						
							| 13 | 
							
								11 12
							 | 
							sylib | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ∃ 𝑎 𝑎  ∈  ∩  ran  𝑈 )  | 
						
						
							| 14 | 
							
								1
							 | 
							fnseqom | 
							⊢ 𝑈  Fn  ω  | 
						
						
							| 15 | 
							
								
							 | 
							fndm | 
							⊢ ( 𝑈  Fn  ω  →  dom  𝑈  =  ω )  | 
						
						
							| 16 | 
							
								14 15
							 | 
							ax-mp | 
							⊢ dom  𝑈  =  ω  | 
						
						
							| 17 | 
							
								
							 | 
							peano1 | 
							⊢ ∅  ∈  ω  | 
						
						
							| 18 | 
							
								17
							 | 
							ne0ii | 
							⊢ ω  ≠  ∅  | 
						
						
							| 19 | 
							
								16 18
							 | 
							eqnetri | 
							⊢ dom  𝑈  ≠  ∅  | 
						
						
							| 20 | 
							
								
							 | 
							dm0rn0 | 
							⊢ ( dom  𝑈  =  ∅  ↔  ran  𝑈  =  ∅ )  | 
						
						
							| 21 | 
							
								20
							 | 
							necon3bii | 
							⊢ ( dom  𝑈  ≠  ∅  ↔  ran  𝑈  ≠  ∅ )  | 
						
						
							| 22 | 
							
								19 21
							 | 
							mpbi | 
							⊢ ran  𝑈  ≠  ∅  | 
						
						
							| 23 | 
							
								
							 | 
							intssuni | 
							⊢ ( ran  𝑈  ≠  ∅  →  ∩  ran  𝑈  ⊆  ∪  ran  𝑈 )  | 
						
						
							| 24 | 
							
								22 23
							 | 
							ax-mp | 
							⊢ ∩  ran  𝑈  ⊆  ∪  ran  𝑈  | 
						
						
							| 25 | 
							
								1
							 | 
							fin23lem16 | 
							⊢ ∪  ran  𝑈  =  ∪  ran  𝑡  | 
						
						
							| 26 | 
							
								24 25
							 | 
							sseqtri | 
							⊢ ∩  ran  𝑈  ⊆  ∪  ran  𝑡  | 
						
						
							| 27 | 
							
								26
							 | 
							sseli | 
							⊢ ( 𝑎  ∈  ∩  ran  𝑈  →  𝑎  ∈  ∪  ran  𝑡 )  | 
						
						
							| 28 | 
							
								
							 | 
							f1fun | 
							⊢ ( 𝑡 : ω –1-1→ 𝑉  →  Fun  𝑡 )  | 
						
						
							| 29 | 
							
								28
							 | 
							adantr | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  Fun  𝑡 )  | 
						
						
							| 30 | 
							
								1 2 3 4 5 6
							 | 
							fin23lem30 | 
							⊢ ( Fun  𝑡  →  ( ∪  ran  𝑍  ∩  ∩  ran  𝑈 )  =  ∅ )  | 
						
						
							| 31 | 
							
								29 30
							 | 
							syl | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ( ∪  ran  𝑍  ∩  ∩  ran  𝑈 )  =  ∅ )  | 
						
						
							| 32 | 
							
								
							 | 
							disj | 
							⊢ ( ( ∪  ran  𝑍  ∩  ∩  ran  𝑈 )  =  ∅  ↔  ∀ 𝑎  ∈  ∪  ran  𝑍 ¬  𝑎  ∈  ∩  ran  𝑈 )  | 
						
						
							| 33 | 
							
								31 32
							 | 
							sylib | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ∀ 𝑎  ∈  ∪  ran  𝑍 ¬  𝑎  ∈  ∩  ran  𝑈 )  | 
						
						
							| 34 | 
							
								
							 | 
							rsp | 
							⊢ ( ∀ 𝑎  ∈  ∪  ran  𝑍 ¬  𝑎  ∈  ∩  ran  𝑈  →  ( 𝑎  ∈  ∪  ran  𝑍  →  ¬  𝑎  ∈  ∩  ran  𝑈 ) )  | 
						
						
							| 35 | 
							
								33 34
							 | 
							syl | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ( 𝑎  ∈  ∪  ran  𝑍  →  ¬  𝑎  ∈  ∩  ran  𝑈 ) )  | 
						
						
							| 36 | 
							
								35
							 | 
							con2d | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ( 𝑎  ∈  ∩  ran  𝑈  →  ¬  𝑎  ∈  ∪  ran  𝑍 ) )  | 
						
						
							| 37 | 
							
								36
							 | 
							imp | 
							⊢ ( ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  ∧  𝑎  ∈  ∩  ran  𝑈 )  →  ¬  𝑎  ∈  ∪  ran  𝑍 )  | 
						
						
							| 38 | 
							
								
							 | 
							nelne1 | 
							⊢ ( ( 𝑎  ∈  ∪  ran  𝑡  ∧  ¬  𝑎  ∈  ∪  ran  𝑍 )  →  ∪  ran  𝑡  ≠  ∪  ran  𝑍 )  | 
						
						
							| 39 | 
							
								27 37 38
							 | 
							syl2an2 | 
							⊢ ( ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  ∧  𝑎  ∈  ∩  ran  𝑈 )  →  ∪  ran  𝑡  ≠  ∪  ran  𝑍 )  | 
						
						
							| 40 | 
							
								39
							 | 
							necomd | 
							⊢ ( ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  ∧  𝑎  ∈  ∩  ran  𝑈 )  →  ∪  ran  𝑍  ≠  ∪  ran  𝑡 )  | 
						
						
							| 41 | 
							
								13 40
							 | 
							exlimddv | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ∪  ran  𝑍  ≠  ∪  ran  𝑡 )  | 
						
						
							| 42 | 
							
								
							 | 
							df-pss | 
							⊢ ( ∪  ran  𝑍  ⊊  ∪  ran  𝑡  ↔  ( ∪  ran  𝑍  ⊆  ∪  ran  𝑡  ∧  ∪  ran  𝑍  ≠  ∪  ran  𝑡 ) )  | 
						
						
							| 43 | 
							
								9 41 42
							 | 
							sylanbrc | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ∪  ran  𝑡  ∈  𝐹 )  →  ∪  ran  𝑍  ⊊  ∪  ran  𝑡 )  | 
						
						
							| 44 | 
							
								7 43
							 | 
							sylan2 | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  ( 𝐺  ∈  𝐹  ∧  ∪  ran  𝑡  ⊆  𝐺 ) )  →  ∪  ran  𝑍  ⊊  ∪  ran  𝑡 )  | 
						
						
							| 45 | 
							
								44
							 | 
							3impb | 
							⊢ ( ( 𝑡 : ω –1-1→ 𝑉  ∧  𝐺  ∈  𝐹  ∧  ∪  ran  𝑡  ⊆  𝐺 )  →  ∪  ran  𝑍  ⊊  ∪  ran  𝑡 )  |