| Step | Hyp | Ref | Expression | 
						
							| 1 |  | cnfcom3c | ⊢ ( 𝐴  ∈  On  →  ∃ 𝑛 ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) ) ) | 
						
							| 2 |  | df-2o | ⊢ 2o  =  suc  1o | 
						
							| 3 | 2 | oveq2i | ⊢ ( ω  ↑o  2o )  =  ( ω  ↑o  suc  1o ) | 
						
							| 4 |  | omelon | ⊢ ω  ∈  On | 
						
							| 5 |  | 1on | ⊢ 1o  ∈  On | 
						
							| 6 |  | oesuc | ⊢ ( ( ω  ∈  On  ∧  1o  ∈  On )  →  ( ω  ↑o  suc  1o )  =  ( ( ω  ↑o  1o )  ·o  ω ) ) | 
						
							| 7 | 4 5 6 | mp2an | ⊢ ( ω  ↑o  suc  1o )  =  ( ( ω  ↑o  1o )  ·o  ω ) | 
						
							| 8 |  | oe1 | ⊢ ( ω  ∈  On  →  ( ω  ↑o  1o )  =  ω ) | 
						
							| 9 | 4 8 | ax-mp | ⊢ ( ω  ↑o  1o )  =  ω | 
						
							| 10 | 9 | oveq1i | ⊢ ( ( ω  ↑o  1o )  ·o  ω )  =  ( ω  ·o  ω ) | 
						
							| 11 | 3 7 10 | 3eqtri | ⊢ ( ω  ↑o  2o )  =  ( ω  ·o  ω ) | 
						
							| 12 |  | omxpen | ⊢ ( ( ω  ∈  On  ∧  ω  ∈  On )  →  ( ω  ·o  ω )  ≈  ( ω  ×  ω ) ) | 
						
							| 13 | 4 4 12 | mp2an | ⊢ ( ω  ·o  ω )  ≈  ( ω  ×  ω ) | 
						
							| 14 | 11 13 | eqbrtri | ⊢ ( ω  ↑o  2o )  ≈  ( ω  ×  ω ) | 
						
							| 15 |  | xpomen | ⊢ ( ω  ×  ω )  ≈  ω | 
						
							| 16 | 14 15 | entri | ⊢ ( ω  ↑o  2o )  ≈  ω | 
						
							| 17 | 16 | a1i | ⊢ ( 𝐴  ∈  On  →  ( ω  ↑o  2o )  ≈  ω ) | 
						
							| 18 |  | bren | ⊢ ( ( ω  ↑o  2o )  ≈  ω  ↔  ∃ 𝑓 𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) | 
						
							| 19 | 17 18 | sylib | ⊢ ( 𝐴  ∈  On  →  ∃ 𝑓 𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) | 
						
							| 20 |  | exdistrv | ⊢ ( ∃ 𝑛 ∃ 𝑓 ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω )  ↔  ( ∃ 𝑛 ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  ∃ 𝑓 𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) ) | 
						
							| 21 |  | simpl | ⊢ ( ( 𝐴  ∈  On  ∧  ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) )  →  𝐴  ∈  On ) | 
						
							| 22 |  | simprl | ⊢ ( ( 𝐴  ∈  On  ∧  ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) )  →  ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) ) ) | 
						
							| 23 |  | sseq2 | ⊢ ( 𝑥  =  𝑏  →  ( ω  ⊆  𝑥  ↔  ω  ⊆  𝑏 ) ) | 
						
							| 24 |  | oveq2 | ⊢ ( 𝑦  =  𝑤  →  ( ω  ↑o  𝑦 )  =  ( ω  ↑o  𝑤 ) ) | 
						
							| 25 | 24 | f1oeq3d | ⊢ ( 𝑦  =  𝑤  →  ( ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 )  ↔  ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 26 | 25 | cbvrexvw | ⊢ ( ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 )  ↔  ∃ 𝑤  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑤 ) ) | 
						
							| 27 |  | fveq2 | ⊢ ( 𝑥  =  𝑏  →  ( 𝑛 ‘ 𝑥 )  =  ( 𝑛 ‘ 𝑏 ) ) | 
						
							| 28 | 27 | f1oeq1d | ⊢ ( 𝑥  =  𝑏  →  ( ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑤 )  ↔  ( 𝑛 ‘ 𝑏 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 29 |  | f1oeq2 | ⊢ ( 𝑥  =  𝑏  →  ( ( 𝑛 ‘ 𝑏 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑤 )  ↔  ( 𝑛 ‘ 𝑏 ) : 𝑏 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 30 | 28 29 | bitrd | ⊢ ( 𝑥  =  𝑏  →  ( ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑤 )  ↔  ( 𝑛 ‘ 𝑏 ) : 𝑏 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 31 | 30 | rexbidv | ⊢ ( 𝑥  =  𝑏  →  ( ∃ 𝑤  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑤 )  ↔  ∃ 𝑤  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑏 ) : 𝑏 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 32 | 26 31 | bitrid | ⊢ ( 𝑥  =  𝑏  →  ( ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 )  ↔  ∃ 𝑤  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑏 ) : 𝑏 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 33 | 23 32 | imbi12d | ⊢ ( 𝑥  =  𝑏  →  ( ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ↔  ( ω  ⊆  𝑏  →  ∃ 𝑤  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑏 ) : 𝑏 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) ) | 
						
							| 34 | 33 | cbvralvw | ⊢ ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ↔  ∀ 𝑏  ∈  𝐴 ( ω  ⊆  𝑏  →  ∃ 𝑤  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑏 ) : 𝑏 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 35 | 22 34 | sylib | ⊢ ( ( 𝐴  ∈  On  ∧  ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) )  →  ∀ 𝑏  ∈  𝐴 ( ω  ⊆  𝑏  →  ∃ 𝑤  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑏 ) : 𝑏 –1-1-onto→ ( ω  ↑o  𝑤 ) ) ) | 
						
							| 36 |  | oveq2 | ⊢ ( 𝑏  =  𝑧  →  ( ω  ↑o  𝑏 )  =  ( ω  ↑o  𝑧 ) ) | 
						
							| 37 | 36 | cbvmptv | ⊢ ( 𝑏  ∈  ( On  ∖  1o )  ↦  ( ω  ↑o  𝑏 ) )  =  ( 𝑧  ∈  ( On  ∖  1o )  ↦  ( ω  ↑o  𝑧 ) ) | 
						
							| 38 | 37 | cnveqi | ⊢ ◡ ( 𝑏  ∈  ( On  ∖  1o )  ↦  ( ω  ↑o  𝑏 ) )  =  ◡ ( 𝑧  ∈  ( On  ∖  1o )  ↦  ( ω  ↑o  𝑧 ) ) | 
						
							| 39 | 38 | fveq1i | ⊢ ( ◡ ( 𝑏  ∈  ( On  ∖  1o )  ↦  ( ω  ↑o  𝑏 ) ) ‘ ran  ( 𝑛 ‘ 𝑏 ) )  =  ( ◡ ( 𝑧  ∈  ( On  ∖  1o )  ↦  ( ω  ↑o  𝑧 ) ) ‘ ran  ( 𝑛 ‘ 𝑏 ) ) | 
						
							| 40 |  | 2on | ⊢ 2o  ∈  On | 
						
							| 41 |  | peano1 | ⊢ ∅  ∈  ω | 
						
							| 42 |  | oen0 | ⊢ ( ( ( ω  ∈  On  ∧  2o  ∈  On )  ∧  ∅  ∈  ω )  →  ∅  ∈  ( ω  ↑o  2o ) ) | 
						
							| 43 | 41 42 | mpan2 | ⊢ ( ( ω  ∈  On  ∧  2o  ∈  On )  →  ∅  ∈  ( ω  ↑o  2o ) ) | 
						
							| 44 | 4 40 43 | mp2an | ⊢ ∅  ∈  ( ω  ↑o  2o ) | 
						
							| 45 |  | eqid | ⊢ ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) )  =  ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) | 
						
							| 46 | 45 | fveqf1o | ⊢ ( ( 𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω  ∧  ∅  ∈  ( ω  ↑o  2o )  ∧  ∅  ∈  ω )  →  ( ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) : ( ω  ↑o  2o ) –1-1-onto→ ω  ∧  ( ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) ‘ ∅ )  =  ∅ ) ) | 
						
							| 47 | 44 41 46 | mp3an23 | ⊢ ( 𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω  →  ( ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) : ( ω  ↑o  2o ) –1-1-onto→ ω  ∧  ( ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) ‘ ∅ )  =  ∅ ) ) | 
						
							| 48 | 47 | ad2antll | ⊢ ( ( 𝐴  ∈  On  ∧  ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) )  →  ( ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) : ( ω  ↑o  2o ) –1-1-onto→ ω  ∧  ( ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) ‘ ∅ )  =  ∅ ) ) | 
						
							| 49 | 48 | simpld | ⊢ ( ( 𝐴  ∈  On  ∧  ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) )  →  ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) : ( ω  ↑o  2o ) –1-1-onto→ ω ) | 
						
							| 50 | 48 | simprd | ⊢ ( ( 𝐴  ∈  On  ∧  ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) )  →  ( ( 𝑓  ∘  ( (  I   ↾  ( ( ω  ↑o  2o )  ∖  { ∅ ,  ( ◡ 𝑓 ‘ ∅ ) } ) )  ∪  { 〈 ∅ ,  ( ◡ 𝑓 ‘ ∅ ) 〉 ,  〈 ( ◡ 𝑓 ‘ ∅ ) ,  ∅ 〉 } ) ) ‘ ∅ )  =  ∅ ) | 
						
							| 51 | 21 35 39 49 50 | infxpenc2lem3 | ⊢ ( ( 𝐴  ∈  On  ∧  ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω ) )  →  ∃ 𝑔 ∀ 𝑏  ∈  𝐴 ( ω  ⊆  𝑏  →  ( 𝑔 ‘ 𝑏 ) : ( 𝑏  ×  𝑏 ) –1-1-onto→ 𝑏 ) ) | 
						
							| 52 | 51 | ex | ⊢ ( 𝐴  ∈  On  →  ( ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω )  →  ∃ 𝑔 ∀ 𝑏  ∈  𝐴 ( ω  ⊆  𝑏  →  ( 𝑔 ‘ 𝑏 ) : ( 𝑏  ×  𝑏 ) –1-1-onto→ 𝑏 ) ) ) | 
						
							| 53 | 52 | exlimdvv | ⊢ ( 𝐴  ∈  On  →  ( ∃ 𝑛 ∃ 𝑓 ( ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω )  →  ∃ 𝑔 ∀ 𝑏  ∈  𝐴 ( ω  ⊆  𝑏  →  ( 𝑔 ‘ 𝑏 ) : ( 𝑏  ×  𝑏 ) –1-1-onto→ 𝑏 ) ) ) | 
						
							| 54 | 20 53 | biimtrrid | ⊢ ( 𝐴  ∈  On  →  ( ( ∃ 𝑛 ∀ 𝑥  ∈  𝐴 ( ω  ⊆  𝑥  →  ∃ 𝑦  ∈  ( On  ∖  1o ) ( 𝑛 ‘ 𝑥 ) : 𝑥 –1-1-onto→ ( ω  ↑o  𝑦 ) )  ∧  ∃ 𝑓 𝑓 : ( ω  ↑o  2o ) –1-1-onto→ ω )  →  ∃ 𝑔 ∀ 𝑏  ∈  𝐴 ( ω  ⊆  𝑏  →  ( 𝑔 ‘ 𝑏 ) : ( 𝑏  ×  𝑏 ) –1-1-onto→ 𝑏 ) ) ) | 
						
							| 55 | 1 19 54 | mp2and | ⊢ ( 𝐴  ∈  On  →  ∃ 𝑔 ∀ 𝑏  ∈  𝐴 ( ω  ⊆  𝑏  →  ( 𝑔 ‘ 𝑏 ) : ( 𝑏  ×  𝑏 ) –1-1-onto→ 𝑏 ) ) |