| Step | Hyp | Ref | Expression | 
						
							| 1 |  | df-oms | ⊢ toOMeas  =  ( 𝑟  ∈  V  ↦  ( 𝑎  ∈  𝒫  ∪  dom  𝑟  ↦  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑟  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑟 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  ) ) ) | 
						
							| 2 |  | dmeq | ⊢ ( 𝑟  =  𝑅  →  dom  𝑟  =  dom  𝑅 ) | 
						
							| 3 | 2 | unieqd | ⊢ ( 𝑟  =  𝑅  →  ∪  dom  𝑟  =  ∪  dom  𝑅 ) | 
						
							| 4 | 3 | pweqd | ⊢ ( 𝑟  =  𝑅  →  𝒫  ∪  dom  𝑟  =  𝒫  ∪  dom  𝑅 ) | 
						
							| 5 | 2 | pweqd | ⊢ ( 𝑟  =  𝑅  →  𝒫  dom  𝑟  =  𝒫  dom  𝑅 ) | 
						
							| 6 |  | rabeq | ⊢ ( 𝒫  dom  𝑟  =  𝒫  dom  𝑅  →  { 𝑧  ∈  𝒫  dom  𝑟  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  =  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) } ) | 
						
							| 7 | 5 6 | syl | ⊢ ( 𝑟  =  𝑅  →  { 𝑧  ∈  𝒫  dom  𝑟  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  =  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) } ) | 
						
							| 8 |  | simpl | ⊢ ( ( 𝑟  =  𝑅  ∧  𝑦  ∈  𝑥 )  →  𝑟  =  𝑅 ) | 
						
							| 9 | 8 | fveq1d | ⊢ ( ( 𝑟  =  𝑅  ∧  𝑦  ∈  𝑥 )  →  ( 𝑟 ‘ 𝑦 )  =  ( 𝑅 ‘ 𝑦 ) ) | 
						
							| 10 | 9 | esumeq2dv | ⊢ ( 𝑟  =  𝑅  →  Σ* 𝑦  ∈  𝑥 ( 𝑟 ‘ 𝑦 )  =  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) | 
						
							| 11 | 7 10 | mpteq12dv | ⊢ ( 𝑟  =  𝑅  →  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑟  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑟 ‘ 𝑦 ) )  =  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) ) | 
						
							| 12 | 11 | rneqd | ⊢ ( 𝑟  =  𝑅  →  ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑟  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑟 ‘ 𝑦 ) )  =  ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) ) | 
						
							| 13 | 12 | infeq1d | ⊢ ( 𝑟  =  𝑅  →  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑟  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑟 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  )  =  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  ) ) | 
						
							| 14 | 4 13 | mpteq12dv | ⊢ ( 𝑟  =  𝑅  →  ( 𝑎  ∈  𝒫  ∪  dom  𝑟  ↦  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑟  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑟 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  ) )  =  ( 𝑎  ∈  𝒫  ∪  dom  𝑅  ↦  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  ) ) ) | 
						
							| 15 |  | id | ⊢ ( 𝑅  ∈  V  →  𝑅  ∈  V ) | 
						
							| 16 |  | dmexg | ⊢ ( 𝑅  ∈  V  →  dom  𝑅  ∈  V ) | 
						
							| 17 |  | uniexg | ⊢ ( dom  𝑅  ∈  V  →  ∪  dom  𝑅  ∈  V ) | 
						
							| 18 |  | pwexg | ⊢ ( ∪  dom  𝑅  ∈  V  →  𝒫  ∪  dom  𝑅  ∈  V ) | 
						
							| 19 |  | mptexg | ⊢ ( 𝒫  ∪  dom  𝑅  ∈  V  →  ( 𝑎  ∈  𝒫  ∪  dom  𝑅  ↦  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  ) )  ∈  V ) | 
						
							| 20 | 16 17 18 19 | 4syl | ⊢ ( 𝑅  ∈  V  →  ( 𝑎  ∈  𝒫  ∪  dom  𝑅  ↦  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  ) )  ∈  V ) | 
						
							| 21 | 1 14 15 20 | fvmptd3 | ⊢ ( 𝑅  ∈  V  →  ( toOMeas ‘ 𝑅 )  =  ( 𝑎  ∈  𝒫  ∪  dom  𝑅  ↦  inf ( ran  ( 𝑥  ∈  { 𝑧  ∈  𝒫  dom  𝑅  ∣  ( 𝑎  ⊆  ∪  𝑧  ∧  𝑧  ≼  ω ) }  ↦  Σ* 𝑦  ∈  𝑥 ( 𝑅 ‘ 𝑦 ) ) ,  ( 0 [,] +∞ ) ,   <  ) ) ) |