| Step | Hyp | Ref | Expression | 
						
							| 1 |  | simpr | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  𝐸  =  ( ω  ↑o  𝐷 ) ) | 
						
							| 2 |  | omelon | ⊢ ω  ∈  On | 
						
							| 3 |  | simpl | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  𝐷  ∈  On ) | 
						
							| 4 |  | oecl | ⊢ ( ( ω  ∈  On  ∧  𝐷  ∈  On )  →  ( ω  ↑o  𝐷 )  ∈  On ) | 
						
							| 5 | 2 3 4 | sylancr | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ( ω  ↑o  𝐷 )  ∈  On ) | 
						
							| 6 | 1 5 | eqeltrd | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  𝐸  ∈  On ) | 
						
							| 7 | 3 2 | jctil | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ( ω  ∈  On  ∧  𝐷  ∈  On ) ) | 
						
							| 8 |  | peano1 | ⊢ ∅  ∈  ω | 
						
							| 9 |  | oen0 | ⊢ ( ( ( ω  ∈  On  ∧  𝐷  ∈  On )  ∧  ∅  ∈  ω )  →  ∅  ∈  ( ω  ↑o  𝐷 ) ) | 
						
							| 10 | 7 8 9 | sylancl | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ∅  ∈  ( ω  ↑o  𝐷 ) ) | 
						
							| 11 | 10 1 | eleqtrrd | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ∅  ∈  𝐸 ) | 
						
							| 12 |  | oveq1 | ⊢ ( 𝑥  =  ∅  →  ( 𝑥  +o  𝐸 )  =  ( ∅  +o  𝐸 ) ) | 
						
							| 13 | 12 | sseq2d | ⊢ ( 𝑥  =  ∅  →  ( 𝐸  ⊆  ( 𝑥  +o  𝐸 )  ↔  𝐸  ⊆  ( ∅  +o  𝐸 ) ) ) | 
						
							| 14 | 13 | adantl | ⊢ ( ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  ∧  𝑥  =  ∅ )  →  ( 𝐸  ⊆  ( 𝑥  +o  𝐸 )  ↔  𝐸  ⊆  ( ∅  +o  𝐸 ) ) ) | 
						
							| 15 |  | oa0r | ⊢ ( 𝐸  ∈  On  →  ( ∅  +o  𝐸 )  =  𝐸 ) | 
						
							| 16 | 6 15 | syl | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ( ∅  +o  𝐸 )  =  𝐸 ) | 
						
							| 17 |  | ssid | ⊢ ( ∅  +o  𝐸 )  ⊆  ( ∅  +o  𝐸 ) | 
						
							| 18 | 16 17 | eqsstrrdi | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  𝐸  ⊆  ( ∅  +o  𝐸 ) ) | 
						
							| 19 | 11 14 18 | rspcedvd | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ∃ 𝑥  ∈  𝐸 𝐸  ⊆  ( 𝑥  +o  𝐸 ) ) | 
						
							| 20 |  | ssiun | ⊢ ( ∃ 𝑥  ∈  𝐸 𝐸  ⊆  ( 𝑥  +o  𝐸 )  →  𝐸  ⊆  ∪  𝑥  ∈  𝐸 ( 𝑥  +o  𝐸 ) ) | 
						
							| 21 | 19 20 | syl | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  𝐸  ⊆  ∪  𝑥  ∈  𝐸 ( 𝑥  +o  𝐸 ) ) | 
						
							| 22 | 1 | eleq2d | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ( 𝑥  ∈  𝐸  ↔  𝑥  ∈  ( ω  ↑o  𝐷 ) ) ) | 
						
							| 23 | 22 | biimpa | ⊢ ( ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  ∧  𝑥  ∈  𝐸 )  →  𝑥  ∈  ( ω  ↑o  𝐷 ) ) | 
						
							| 24 | 6 | adantr | ⊢ ( ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  ∧  𝑥  ∈  𝐸 )  →  𝐸  ∈  On ) | 
						
							| 25 | 1 | adantr | ⊢ ( ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  ∧  𝑥  ∈  𝐸 )  →  𝐸  =  ( ω  ↑o  𝐷 ) ) | 
						
							| 26 |  | ssid | ⊢ 𝐸  ⊆  𝐸 | 
						
							| 27 | 25 26 | eqsstrrdi | ⊢ ( ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  ∧  𝑥  ∈  𝐸 )  →  ( ω  ↑o  𝐷 )  ⊆  𝐸 ) | 
						
							| 28 |  | oaabs2 | ⊢ ( ( ( 𝑥  ∈  ( ω  ↑o  𝐷 )  ∧  𝐸  ∈  On )  ∧  ( ω  ↑o  𝐷 )  ⊆  𝐸 )  →  ( 𝑥  +o  𝐸 )  =  𝐸 ) | 
						
							| 29 | 23 24 27 28 | syl21anc | ⊢ ( ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  ∧  𝑥  ∈  𝐸 )  →  ( 𝑥  +o  𝐸 )  =  𝐸 ) | 
						
							| 30 | 29 26 | eqsstrdi | ⊢ ( ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  ∧  𝑥  ∈  𝐸 )  →  ( 𝑥  +o  𝐸 )  ⊆  𝐸 ) | 
						
							| 31 | 30 | iunssd | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ∪  𝑥  ∈  𝐸 ( 𝑥  +o  𝐸 )  ⊆  𝐸 ) | 
						
							| 32 | 21 31 | eqssd | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  𝐸  =  ∪  𝑥  ∈  𝐸 ( 𝑥  +o  𝐸 ) ) | 
						
							| 33 | 6 6 32 | 3jca | ⊢ ( ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) )  →  ( 𝐸  ∈  On  ∧  𝐸  ∈  On  ∧  𝐸  =  ∪  𝑥  ∈  𝐸 ( 𝑥  +o  𝐸 ) ) ) | 
						
							| 34 |  | ofoafg | ⊢ ( ( ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑊  ∧  𝐶  =  ( 𝐴  ∩  𝐵 ) )  ∧  ( 𝐸  ∈  On  ∧  𝐸  ∈  On  ∧  𝐸  =  ∪  𝑥  ∈  𝐸 ( 𝑥  +o  𝐸 ) ) )  →  (  ∘f   +o   ↾  ( ( 𝐸  ↑m  𝐴 )  ×  ( 𝐸  ↑m  𝐵 ) ) ) : ( ( 𝐸  ↑m  𝐴 )  ×  ( 𝐸  ↑m  𝐵 ) ) ⟶ ( 𝐸  ↑m  𝐶 ) ) | 
						
							| 35 | 33 34 | sylan2 | ⊢ ( ( ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑊  ∧  𝐶  =  ( 𝐴  ∩  𝐵 ) )  ∧  ( 𝐷  ∈  On  ∧  𝐸  =  ( ω  ↑o  𝐷 ) ) )  →  (  ∘f   +o   ↾  ( ( 𝐸  ↑m  𝐴 )  ×  ( 𝐸  ↑m  𝐵 ) ) ) : ( ( 𝐸  ↑m  𝐴 )  ×  ( 𝐸  ↑m  𝐵 ) ) ⟶ ( 𝐸  ↑m  𝐶 ) ) |