| Step | Hyp | Ref | Expression | 
						
							| 1 |  | efgval.w | ⊢ 𝑊  =  (  I  ‘ Word  ( 𝐼  ×  2o ) ) | 
						
							| 2 |  | efgval.r | ⊢  ∼   =  (  ~FG  ‘ 𝐼 ) | 
						
							| 3 |  | efgval2.m | ⊢ 𝑀  =  ( 𝑦  ∈  𝐼 ,  𝑧  ∈  2o  ↦  〈 𝑦 ,  ( 1o  ∖  𝑧 ) 〉 ) | 
						
							| 4 |  | efgval2.t | ⊢ 𝑇  =  ( 𝑣  ∈  𝑊  ↦  ( 𝑛  ∈  ( 0 ... ( ♯ ‘ 𝑣 ) ) ,  𝑤  ∈  ( 𝐼  ×  2o )  ↦  ( 𝑣  splice  〈 𝑛 ,  𝑛 ,  〈“ 𝑤 ( 𝑀 ‘ 𝑤 ) ”〉 〉 ) ) ) | 
						
							| 5 |  | efgred.d | ⊢ 𝐷  =  ( 𝑊  ∖  ∪  𝑥  ∈  𝑊 ran  ( 𝑇 ‘ 𝑥 ) ) | 
						
							| 6 |  | efgred.s | ⊢ 𝑆  =  ( 𝑚  ∈  { 𝑡  ∈  ( Word  𝑊  ∖  { ∅ } )  ∣  ( ( 𝑡 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑘  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) ) ) }  ↦  ( 𝑚 ‘ ( ( ♯ ‘ 𝑚 )  −  1 ) ) ) | 
						
							| 7 |  | fveq1 | ⊢ ( 𝑓  =  𝐹  →  ( 𝑓 ‘ 0 )  =  ( 𝐹 ‘ 0 ) ) | 
						
							| 8 | 7 | eleq1d | ⊢ ( 𝑓  =  𝐹  →  ( ( 𝑓 ‘ 0 )  ∈  𝐷  ↔  ( 𝐹 ‘ 0 )  ∈  𝐷 ) ) | 
						
							| 9 |  | fveq2 | ⊢ ( 𝑓  =  𝐹  →  ( ♯ ‘ 𝑓 )  =  ( ♯ ‘ 𝐹 ) ) | 
						
							| 10 | 9 | oveq2d | ⊢ ( 𝑓  =  𝐹  →  ( 1 ..^ ( ♯ ‘ 𝑓 ) )  =  ( 1 ..^ ( ♯ ‘ 𝐹 ) ) ) | 
						
							| 11 |  | fveq1 | ⊢ ( 𝑓  =  𝐹  →  ( 𝑓 ‘ 𝑖 )  =  ( 𝐹 ‘ 𝑖 ) ) | 
						
							| 12 |  | fveq1 | ⊢ ( 𝑓  =  𝐹  →  ( 𝑓 ‘ ( 𝑖  −  1 ) )  =  ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) | 
						
							| 13 | 12 | fveq2d | ⊢ ( 𝑓  =  𝐹  →  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) )  =  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) | 
						
							| 14 | 13 | rneqd | ⊢ ( 𝑓  =  𝐹  →  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) )  =  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) | 
						
							| 15 | 11 14 | eleq12d | ⊢ ( 𝑓  =  𝐹  →  ( ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) )  ↔  ( 𝐹 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) ) | 
						
							| 16 | 10 15 | raleqbidv | ⊢ ( 𝑓  =  𝐹  →  ( ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) )  ↔  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝐹 ) ) ( 𝐹 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) ) | 
						
							| 17 | 8 16 | anbi12d | ⊢ ( 𝑓  =  𝐹  →  ( ( ( 𝑓 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) )  ↔  ( ( 𝐹 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝐹 ) ) ( 𝐹 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) ) ) | 
						
							| 18 | 1 2 3 4 5 6 | efgsf | ⊢ 𝑆 : { 𝑡  ∈  ( Word  𝑊  ∖  { ∅ } )  ∣  ( ( 𝑡 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑘  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) ) ) } ⟶ 𝑊 | 
						
							| 19 | 18 | fdmi | ⊢ dom  𝑆  =  { 𝑡  ∈  ( Word  𝑊  ∖  { ∅ } )  ∣  ( ( 𝑡 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑘  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) ) ) } | 
						
							| 20 |  | fveq1 | ⊢ ( 𝑡  =  𝑓  →  ( 𝑡 ‘ 0 )  =  ( 𝑓 ‘ 0 ) ) | 
						
							| 21 | 20 | eleq1d | ⊢ ( 𝑡  =  𝑓  →  ( ( 𝑡 ‘ 0 )  ∈  𝐷  ↔  ( 𝑓 ‘ 0 )  ∈  𝐷 ) ) | 
						
							| 22 |  | fveq2 | ⊢ ( 𝑘  =  𝑖  →  ( 𝑡 ‘ 𝑘 )  =  ( 𝑡 ‘ 𝑖 ) ) | 
						
							| 23 |  | fvoveq1 | ⊢ ( 𝑘  =  𝑖  →  ( 𝑡 ‘ ( 𝑘  −  1 ) )  =  ( 𝑡 ‘ ( 𝑖  −  1 ) ) ) | 
						
							| 24 | 23 | fveq2d | ⊢ ( 𝑘  =  𝑖  →  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) )  =  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) ) ) | 
						
							| 25 | 24 | rneqd | ⊢ ( 𝑘  =  𝑖  →  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) )  =  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) ) ) | 
						
							| 26 | 22 25 | eleq12d | ⊢ ( 𝑘  =  𝑖  →  ( ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) )  ↔  ( 𝑡 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) ) ) ) | 
						
							| 27 | 26 | cbvralvw | ⊢ ( ∀ 𝑘  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) )  ↔  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) ) ) | 
						
							| 28 |  | fveq2 | ⊢ ( 𝑡  =  𝑓  →  ( ♯ ‘ 𝑡 )  =  ( ♯ ‘ 𝑓 ) ) | 
						
							| 29 | 28 | oveq2d | ⊢ ( 𝑡  =  𝑓  →  ( 1 ..^ ( ♯ ‘ 𝑡 ) )  =  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ) | 
						
							| 30 |  | fveq1 | ⊢ ( 𝑡  =  𝑓  →  ( 𝑡 ‘ 𝑖 )  =  ( 𝑓 ‘ 𝑖 ) ) | 
						
							| 31 |  | fveq1 | ⊢ ( 𝑡  =  𝑓  →  ( 𝑡 ‘ ( 𝑖  −  1 ) )  =  ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) | 
						
							| 32 | 31 | fveq2d | ⊢ ( 𝑡  =  𝑓  →  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) )  =  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) | 
						
							| 33 | 32 | rneqd | ⊢ ( 𝑡  =  𝑓  →  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) )  =  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) | 
						
							| 34 | 30 33 | eleq12d | ⊢ ( 𝑡  =  𝑓  →  ( ( 𝑡 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) )  ↔  ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) ) | 
						
							| 35 | 29 34 | raleqbidv | ⊢ ( 𝑡  =  𝑓  →  ( ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑖  −  1 ) ) )  ↔  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) ) | 
						
							| 36 | 27 35 | bitrid | ⊢ ( 𝑡  =  𝑓  →  ( ∀ 𝑘  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) )  ↔  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) ) | 
						
							| 37 | 21 36 | anbi12d | ⊢ ( 𝑡  =  𝑓  →  ( ( ( 𝑡 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑘  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) ) )  ↔  ( ( 𝑓 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) ) ) | 
						
							| 38 | 37 | cbvrabv | ⊢ { 𝑡  ∈  ( Word  𝑊  ∖  { ∅ } )  ∣  ( ( 𝑡 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑘  ∈  ( 1 ..^ ( ♯ ‘ 𝑡 ) ) ( 𝑡 ‘ 𝑘 )  ∈  ran  ( 𝑇 ‘ ( 𝑡 ‘ ( 𝑘  −  1 ) ) ) ) }  =  { 𝑓  ∈  ( Word  𝑊  ∖  { ∅ } )  ∣  ( ( 𝑓 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) } | 
						
							| 39 | 19 38 | eqtri | ⊢ dom  𝑆  =  { 𝑓  ∈  ( Word  𝑊  ∖  { ∅ } )  ∣  ( ( 𝑓 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝑓 ) ) ( 𝑓 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝑓 ‘ ( 𝑖  −  1 ) ) ) ) } | 
						
							| 40 | 17 39 | elrab2 | ⊢ ( 𝐹  ∈  dom  𝑆  ↔  ( 𝐹  ∈  ( Word  𝑊  ∖  { ∅ } )  ∧  ( ( 𝐹 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝐹 ) ) ( 𝐹 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) ) ) | 
						
							| 41 |  | 3anass | ⊢ ( ( 𝐹  ∈  ( Word  𝑊  ∖  { ∅ } )  ∧  ( 𝐹 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝐹 ) ) ( 𝐹 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) )  ↔  ( 𝐹  ∈  ( Word  𝑊  ∖  { ∅ } )  ∧  ( ( 𝐹 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝐹 ) ) ( 𝐹 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) ) ) | 
						
							| 42 | 40 41 | bitr4i | ⊢ ( 𝐹  ∈  dom  𝑆  ↔  ( 𝐹  ∈  ( Word  𝑊  ∖  { ∅ } )  ∧  ( 𝐹 ‘ 0 )  ∈  𝐷  ∧  ∀ 𝑖  ∈  ( 1 ..^ ( ♯ ‘ 𝐹 ) ) ( 𝐹 ‘ 𝑖 )  ∈  ran  ( 𝑇 ‘ ( 𝐹 ‘ ( 𝑖  −  1 ) ) ) ) ) |