| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ovolval4lem2.a | ⊢ ( 𝜑  →  𝐴  ⊆  ℝ ) | 
						
							| 2 |  | ovolval4lem2.m | ⊢ 𝑀  =  { 𝑦  ∈  ℝ*  ∣  ∃ 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) } | 
						
							| 3 |  | ovolval4lem2.g | ⊢ 𝐺  =  ( 𝑛  ∈  ℕ  ↦  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉 ) | 
						
							| 4 |  | iftrue | ⊢ ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  →  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) )  =  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ) | 
						
							| 5 | 4 | opeq2d | ⊢ ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  =  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉 ) | 
						
							| 6 | 5 | adantl | ⊢ ( ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  ∧  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  =  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉 ) | 
						
							| 7 |  | df-br | ⊢ ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  ↔  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉  ∈   ≤  ) | 
						
							| 8 | 7 | biimpi | ⊢ ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉  ∈   ≤  ) | 
						
							| 9 | 8 | adantl | ⊢ ( ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  ∧  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉  ∈   ≤  ) | 
						
							| 10 | 6 9 | eqeltrd | ⊢ ( ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  ∧  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  ∈   ≤  ) | 
						
							| 11 |  | iffalse | ⊢ ( ¬  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  →  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) )  =  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) | 
						
							| 12 | 11 | opeq2d | ⊢ ( ¬  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  =  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉 ) | 
						
							| 13 | 12 | adantl | ⊢ ( ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  ∧  ¬  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  =  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉 ) | 
						
							| 14 |  | elmapi | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  𝑓 : ℕ ⟶ ( ℝ  ×  ℝ ) ) | 
						
							| 15 | 14 | ffvelcdmda | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  ( 𝑓 ‘ 𝑛 )  ∈  ( ℝ  ×  ℝ ) ) | 
						
							| 16 |  | xp1st | ⊢ ( ( 𝑓 ‘ 𝑛 )  ∈  ( ℝ  ×  ℝ )  →  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ∈  ℝ ) | 
						
							| 17 | 15 16 | syl | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ∈  ℝ ) | 
						
							| 18 | 17 | leidd | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) | 
						
							| 19 |  | df-br | ⊢ ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ↔  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉  ∈   ≤  ) | 
						
							| 20 | 18 19 | sylib | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉  ∈   ≤  ) | 
						
							| 21 | 20 | adantr | ⊢ ( ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  ∧  ¬  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) 〉  ∈   ≤  ) | 
						
							| 22 | 13 21 | eqeltrd | ⊢ ( ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  ∧  ¬  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  ∈   ≤  ) | 
						
							| 23 | 10 22 | pm2.61dan | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  ∈   ≤  ) | 
						
							| 24 |  | xp2nd | ⊢ ( ( 𝑓 ‘ 𝑛 )  ∈  ( ℝ  ×  ℝ )  →  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  ∈  ℝ ) | 
						
							| 25 | 15 24 | syl | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) )  ∈  ℝ ) | 
						
							| 26 | 25 17 | ifcld | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) )  ∈  ℝ ) | 
						
							| 27 |  | opelxpi | ⊢ ( ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ∈  ℝ  ∧  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) )  ∈  ℝ )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  ∈  ( ℝ  ×  ℝ ) ) | 
						
							| 28 | 17 26 27 | syl2anc | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  ∈  ( ℝ  ×  ℝ ) ) | 
						
							| 29 | 23 28 | elind | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑛  ∈  ℕ )  →  〈 ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  if ( ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ,  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) 〉  ∈  (  ≤   ∩  ( ℝ  ×  ℝ ) ) ) | 
						
							| 30 | 29 3 | fmptd | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  𝐺 : ℕ ⟶ (  ≤   ∩  ( ℝ  ×  ℝ ) ) ) | 
						
							| 31 |  | reex | ⊢ ℝ  ∈  V | 
						
							| 32 | 31 31 | xpex | ⊢ ( ℝ  ×  ℝ )  ∈  V | 
						
							| 33 | 32 | inex2 | ⊢ (  ≤   ∩  ( ℝ  ×  ℝ ) )  ∈  V | 
						
							| 34 | 33 | a1i | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  (  ≤   ∩  ( ℝ  ×  ℝ ) )  ∈  V ) | 
						
							| 35 |  | nnex | ⊢ ℕ  ∈  V | 
						
							| 36 | 35 | a1i | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ℕ  ∈  V ) | 
						
							| 37 | 34 36 | elmapd | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( 𝐺  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  ↔  𝐺 : ℕ ⟶ (  ≤   ∩  ( ℝ  ×  ℝ ) ) ) ) | 
						
							| 38 | 30 37 | mpbird | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  𝐺  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ) | 
						
							| 39 | 38 | adantr | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) )  →  𝐺  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ) | 
						
							| 40 |  | simpr | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 ) )  →  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 ) ) | 
						
							| 41 |  | rexpssxrxp | ⊢ ( ℝ  ×  ℝ )  ⊆  ( ℝ*  ×  ℝ* ) | 
						
							| 42 | 41 | a1i | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( ℝ  ×  ℝ )  ⊆  ( ℝ*  ×  ℝ* ) ) | 
						
							| 43 | 14 42 | fssd | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  𝑓 : ℕ ⟶ ( ℝ*  ×  ℝ* ) ) | 
						
							| 44 |  | 2fveq3 | ⊢ ( 𝑘  =  𝑛  →  ( 1st  ‘ ( 𝑓 ‘ 𝑘 ) )  =  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) ) ) | 
						
							| 45 |  | 2fveq3 | ⊢ ( 𝑘  =  𝑛  →  ( 2nd  ‘ ( 𝑓 ‘ 𝑘 ) )  =  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ) | 
						
							| 46 | 44 45 | breq12d | ⊢ ( 𝑘  =  𝑛  →  ( ( 1st  ‘ ( 𝑓 ‘ 𝑘 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑘 ) )  ↔  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) ) ) | 
						
							| 47 | 46 | cbvrabv | ⊢ { 𝑘  ∈  ℕ  ∣  ( 1st  ‘ ( 𝑓 ‘ 𝑘 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑘 ) ) }  =  { 𝑛  ∈  ℕ  ∣  ( 1st  ‘ ( 𝑓 ‘ 𝑛 ) )  ≤  ( 2nd  ‘ ( 𝑓 ‘ 𝑛 ) ) } | 
						
							| 48 | 43 3 47 | ovolval4lem1 | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( ∪  ran  ( (,)  ∘  𝑓 )  =  ∪  ran  ( (,)  ∘  𝐺 )  ∧  ( vol  ∘  ( (,)  ∘  𝑓 ) )  =  ( vol  ∘  ( (,)  ∘  𝐺 ) ) ) ) | 
						
							| 49 | 48 | simpld | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ∪  ran  ( (,)  ∘  𝑓 )  =  ∪  ran  ( (,)  ∘  𝐺 ) ) | 
						
							| 50 | 49 | adantr | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 ) )  →  ∪  ran  ( (,)  ∘  𝑓 )  =  ∪  ran  ( (,)  ∘  𝐺 ) ) | 
						
							| 51 | 40 50 | sseqtrd | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 ) )  →  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝐺 ) ) | 
						
							| 52 | 51 | adantrr | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) )  →  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝐺 ) ) | 
						
							| 53 |  | simpr | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) )  →  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) | 
						
							| 54 | 48 | simprd | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( vol  ∘  ( (,)  ∘  𝑓 ) )  =  ( vol  ∘  ( (,)  ∘  𝐺 ) ) ) | 
						
							| 55 |  | coass | ⊢ ( ( vol  ∘  (,) )  ∘  𝑓 )  =  ( vol  ∘  ( (,)  ∘  𝑓 ) ) | 
						
							| 56 | 55 | a1i | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( ( vol  ∘  (,) )  ∘  𝑓 )  =  ( vol  ∘  ( (,)  ∘  𝑓 ) ) ) | 
						
							| 57 |  | coass | ⊢ ( ( vol  ∘  (,) )  ∘  𝐺 )  =  ( vol  ∘  ( (,)  ∘  𝐺 ) ) | 
						
							| 58 | 57 | a1i | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( ( vol  ∘  (,) )  ∘  𝐺 )  =  ( vol  ∘  ( (,)  ∘  𝐺 ) ) ) | 
						
							| 59 | 54 56 58 | 3eqtr4d | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( ( vol  ∘  (,) )  ∘  𝑓 )  =  ( ( vol  ∘  (,) )  ∘  𝐺 ) ) | 
						
							| 60 | 59 | fveq2d | ⊢ ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  →  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) )  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) | 
						
							| 61 | 60 | adantr | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) )  →  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) )  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) | 
						
							| 62 | 53 61 | eqtrd | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) )  →  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) | 
						
							| 63 | 62 | adantrl | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) )  →  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) | 
						
							| 64 | 52 63 | jca | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) )  →  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝐺 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) ) | 
						
							| 65 |  | coeq2 | ⊢ ( 𝑔  =  𝐺  →  ( (,)  ∘  𝑔 )  =  ( (,)  ∘  𝐺 ) ) | 
						
							| 66 | 65 | rneqd | ⊢ ( 𝑔  =  𝐺  →  ran  ( (,)  ∘  𝑔 )  =  ran  ( (,)  ∘  𝐺 ) ) | 
						
							| 67 | 66 | unieqd | ⊢ ( 𝑔  =  𝐺  →  ∪  ran  ( (,)  ∘  𝑔 )  =  ∪  ran  ( (,)  ∘  𝐺 ) ) | 
						
							| 68 | 67 | sseq2d | ⊢ ( 𝑔  =  𝐺  →  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ↔  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝐺 ) ) ) | 
						
							| 69 |  | coeq2 | ⊢ ( 𝑔  =  𝐺  →  ( ( vol  ∘  (,) )  ∘  𝑔 )  =  ( ( vol  ∘  (,) )  ∘  𝐺 ) ) | 
						
							| 70 | 69 | fveq2d | ⊢ ( 𝑔  =  𝐺  →  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) )  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) | 
						
							| 71 | 70 | eqeq2d | ⊢ ( 𝑔  =  𝐺  →  ( 𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) )  ↔  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) ) | 
						
							| 72 | 68 71 | anbi12d | ⊢ ( 𝑔  =  𝐺  →  ( ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) )  ↔  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝐺 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) ) ) | 
						
							| 73 | 72 | rspcev | ⊢ ( ( 𝐺  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝐺 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝐺 ) ) ) )  →  ∃ 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) ) | 
						
							| 74 | 39 64 73 | syl2anc | ⊢ ( ( 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) )  →  ∃ 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) ) | 
						
							| 75 | 74 | rexlimiva | ⊢ ( ∃ 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) )  →  ∃ 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) ) | 
						
							| 76 |  | inss2 | ⊢ (  ≤   ∩  ( ℝ  ×  ℝ ) )  ⊆  ( ℝ  ×  ℝ ) | 
						
							| 77 |  | mapss | ⊢ ( ( ( ℝ  ×  ℝ )  ∈  V  ∧  (  ≤   ∩  ( ℝ  ×  ℝ ) )  ⊆  ( ℝ  ×  ℝ ) )  →  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  ⊆  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ) | 
						
							| 78 | 32 76 77 | mp2an | ⊢ ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  ⊆  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) | 
						
							| 79 | 78 | sseli | ⊢ ( 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  →  𝑔  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ) | 
						
							| 80 | 79 | adantr | ⊢ ( ( 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) )  →  𝑔  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ) | 
						
							| 81 |  | simpr | ⊢ ( ( 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) )  →  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) ) | 
						
							| 82 |  | coeq2 | ⊢ ( 𝑓  =  𝑔  →  ( (,)  ∘  𝑓 )  =  ( (,)  ∘  𝑔 ) ) | 
						
							| 83 | 82 | rneqd | ⊢ ( 𝑓  =  𝑔  →  ran  ( (,)  ∘  𝑓 )  =  ran  ( (,)  ∘  𝑔 ) ) | 
						
							| 84 | 83 | unieqd | ⊢ ( 𝑓  =  𝑔  →  ∪  ran  ( (,)  ∘  𝑓 )  =  ∪  ran  ( (,)  ∘  𝑔 ) ) | 
						
							| 85 | 84 | sseq2d | ⊢ ( 𝑓  =  𝑔  →  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ↔  𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 ) ) ) | 
						
							| 86 |  | coeq2 | ⊢ ( 𝑓  =  𝑔  →  ( ( vol  ∘  (,) )  ∘  𝑓 )  =  ( ( vol  ∘  (,) )  ∘  𝑔 ) ) | 
						
							| 87 | 86 | fveq2d | ⊢ ( 𝑓  =  𝑔  →  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) )  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) | 
						
							| 88 | 87 | eqeq2d | ⊢ ( 𝑓  =  𝑔  →  ( 𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) )  ↔  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) ) | 
						
							| 89 | 85 88 | anbi12d | ⊢ ( 𝑓  =  𝑔  →  ( ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) )  ↔  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) ) ) | 
						
							| 90 | 89 | rspcev | ⊢ ( ( 𝑔  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) )  →  ∃ 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) ) | 
						
							| 91 | 80 81 90 | syl2anc | ⊢ ( ( 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ )  ∧  ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) )  →  ∃ 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) ) | 
						
							| 92 | 91 | rexlimiva | ⊢ ( ∃ 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) )  →  ∃ 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) ) | 
						
							| 93 | 75 92 | impbii | ⊢ ( ∃ 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) )  ↔  ∃ 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) ) | 
						
							| 94 | 93 | rabbii | ⊢ { 𝑦  ∈  ℝ*  ∣  ∃ 𝑓  ∈  ( ( ℝ  ×  ℝ )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑓 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑓 ) ) ) }  =  { 𝑦  ∈  ℝ*  ∣  ∃ 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) } | 
						
							| 95 | 2 94 | eqtri | ⊢ 𝑀  =  { 𝑦  ∈  ℝ*  ∣  ∃ 𝑔  ∈  ( (  ≤   ∩  ( ℝ  ×  ℝ ) )  ↑m  ℕ ) ( 𝐴  ⊆  ∪  ran  ( (,)  ∘  𝑔 )  ∧  𝑦  =  ( Σ^ ‘ ( ( vol  ∘  (,) )  ∘  𝑔 ) ) ) } | 
						
							| 96 | 1 95 | ovolval3 | ⊢ ( 𝜑  →  ( vol* ‘ 𝐴 )  =  inf ( 𝑀 ,  ℝ* ,   <  ) ) |