| Step | Hyp | Ref | Expression | 
						
							| 1 |  | wlkiswwlks2lem.f | ⊢ 𝐹  =  ( 𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) )  ↦  ( ◡ 𝐸 ‘ { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) } ) ) | 
						
							| 2 |  | wlkiswwlks2lem.e | ⊢ 𝐸  =  ( iEdg ‘ 𝐺 ) | 
						
							| 3 | 2 | uspgrf1oedg | ⊢ ( 𝐺  ∈  USPGraph  →  𝐸 : dom  𝐸 –1-1-onto→ ( Edg ‘ 𝐺 ) ) | 
						
							| 4 | 2 | rneqi | ⊢ ran  𝐸  =  ran  ( iEdg ‘ 𝐺 ) | 
						
							| 5 |  | edgval | ⊢ ( Edg ‘ 𝐺 )  =  ran  ( iEdg ‘ 𝐺 ) | 
						
							| 6 | 4 5 | eqtr4i | ⊢ ran  𝐸  =  ( Edg ‘ 𝐺 ) | 
						
							| 7 | 6 | a1i | ⊢ ( 𝐺  ∈  USPGraph  →  ran  𝐸  =  ( Edg ‘ 𝐺 ) ) | 
						
							| 8 | 7 | f1oeq3d | ⊢ ( 𝐺  ∈  USPGraph  →  ( 𝐸 : dom  𝐸 –1-1-onto→ ran  𝐸  ↔  𝐸 : dom  𝐸 –1-1-onto→ ( Edg ‘ 𝐺 ) ) ) | 
						
							| 9 | 3 8 | mpbird | ⊢ ( 𝐺  ∈  USPGraph  →  𝐸 : dom  𝐸 –1-1-onto→ ran  𝐸 ) | 
						
							| 10 | 9 | 3ad2ant1 | ⊢ ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  →  𝐸 : dom  𝐸 –1-1-onto→ ran  𝐸 ) | 
						
							| 11 | 10 | ad2antrr | ⊢ ( ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸 )  ∧  𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) )  →  𝐸 : dom  𝐸 –1-1-onto→ ran  𝐸 ) | 
						
							| 12 |  | simpr | ⊢ ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) )  →  𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) ) | 
						
							| 13 |  | fveq2 | ⊢ ( 𝑖  =  𝑥  →  ( 𝑃 ‘ 𝑖 )  =  ( 𝑃 ‘ 𝑥 ) ) | 
						
							| 14 |  | fvoveq1 | ⊢ ( 𝑖  =  𝑥  →  ( 𝑃 ‘ ( 𝑖  +  1 ) )  =  ( 𝑃 ‘ ( 𝑥  +  1 ) ) ) | 
						
							| 15 | 13 14 | preq12d | ⊢ ( 𝑖  =  𝑥  →  { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  =  { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) } ) | 
						
							| 16 | 15 | eleq1d | ⊢ ( 𝑖  =  𝑥  →  ( { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸  ↔  { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) }  ∈  ran  𝐸 ) ) | 
						
							| 17 | 16 | adantl | ⊢ ( ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) )  ∧  𝑖  =  𝑥 )  →  ( { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸  ↔  { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) }  ∈  ran  𝐸 ) ) | 
						
							| 18 | 12 17 | rspcdv | ⊢ ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) )  →  ( ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸  →  { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) }  ∈  ran  𝐸 ) ) | 
						
							| 19 | 18 | impancom | ⊢ ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸 )  →  ( 𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) )  →  { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) }  ∈  ran  𝐸 ) ) | 
						
							| 20 | 19 | imp | ⊢ ( ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸 )  ∧  𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) )  →  { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) }  ∈  ran  𝐸 ) | 
						
							| 21 |  | f1ocnvdm | ⊢ ( ( 𝐸 : dom  𝐸 –1-1-onto→ ran  𝐸  ∧  { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) }  ∈  ran  𝐸 )  →  ( ◡ 𝐸 ‘ { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) } )  ∈  dom  𝐸 ) | 
						
							| 22 | 11 20 21 | syl2anc | ⊢ ( ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸 )  ∧  𝑥  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) )  →  ( ◡ 𝐸 ‘ { ( 𝑃 ‘ 𝑥 ) ,  ( 𝑃 ‘ ( 𝑥  +  1 ) ) } )  ∈  dom  𝐸 ) | 
						
							| 23 | 22 1 | fmptd | ⊢ ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸 )  →  𝐹 : ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) ⟶ dom  𝐸 ) | 
						
							| 24 |  | iswrdi | ⊢ ( 𝐹 : ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) ⟶ dom  𝐸  →  𝐹  ∈  Word  dom  𝐸 ) | 
						
							| 25 | 23 24 | syl | ⊢ ( ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  ∧  ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸 )  →  𝐹  ∈  Word  dom  𝐸 ) | 
						
							| 26 | 25 | ex | ⊢ ( ( 𝐺  ∈  USPGraph  ∧  𝑃  ∈  Word  𝑉  ∧  1  ≤  ( ♯ ‘ 𝑃 ) )  →  ( ∀ 𝑖  ∈  ( 0 ..^ ( ( ♯ ‘ 𝑃 )  −  1 ) ) { ( 𝑃 ‘ 𝑖 ) ,  ( 𝑃 ‘ ( 𝑖  +  1 ) ) }  ∈  ran  𝐸  →  𝐹  ∈  Word  dom  𝐸 ) ) |