| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ioombl1.b | ⊢ 𝐵  =  ( 𝐴 (,) +∞ ) | 
						
							| 2 |  | ioombl1.a | ⊢ ( 𝜑  →  𝐴  ∈  ℝ ) | 
						
							| 3 |  | ioombl1.e | ⊢ ( 𝜑  →  𝐸  ⊆  ℝ ) | 
						
							| 4 |  | ioombl1.v | ⊢ ( 𝜑  →  ( vol* ‘ 𝐸 )  ∈  ℝ ) | 
						
							| 5 |  | ioombl1.c | ⊢ ( 𝜑  →  𝐶  ∈  ℝ+ ) | 
						
							| 6 |  | ioombl1.s | ⊢ 𝑆  =  seq 1 (  +  ,  ( ( abs  ∘   −  )  ∘  𝐹 ) ) | 
						
							| 7 |  | ioombl1.t | ⊢ 𝑇  =  seq 1 (  +  ,  ( ( abs  ∘   −  )  ∘  𝐺 ) ) | 
						
							| 8 |  | ioombl1.u | ⊢ 𝑈  =  seq 1 (  +  ,  ( ( abs  ∘   −  )  ∘  𝐻 ) ) | 
						
							| 9 |  | ioombl1.f1 | ⊢ ( 𝜑  →  𝐹 : ℕ ⟶ (  ≤   ∩  ( ℝ  ×  ℝ ) ) ) | 
						
							| 10 |  | ioombl1.f2 | ⊢ ( 𝜑  →  𝐸  ⊆  ∪  ran  ( (,)  ∘  𝐹 ) ) | 
						
							| 11 |  | ioombl1.f3 | ⊢ ( 𝜑  →  sup ( ran  𝑆 ,  ℝ* ,   <  )  ≤  ( ( vol* ‘ 𝐸 )  +  𝐶 ) ) | 
						
							| 12 |  | ioombl1.p | ⊢ 𝑃  =  ( 1st  ‘ ( 𝐹 ‘ 𝑛 ) ) | 
						
							| 13 |  | ioombl1.q | ⊢ 𝑄  =  ( 2nd  ‘ ( 𝐹 ‘ 𝑛 ) ) | 
						
							| 14 |  | ioombl1.g | ⊢ 𝐺  =  ( 𝑛  ∈  ℕ  ↦  〈 if ( if ( 𝑃  ≤  𝐴 ,  𝐴 ,  𝑃 )  ≤  𝑄 ,  if ( 𝑃  ≤  𝐴 ,  𝐴 ,  𝑃 ) ,  𝑄 ) ,  𝑄 〉 ) | 
						
							| 15 |  | ioombl1.h | ⊢ 𝐻  =  ( 𝑛  ∈  ℕ  ↦  〈 𝑃 ,  if ( if ( 𝑃  ≤  𝐴 ,  𝐴 ,  𝑃 )  ≤  𝑄 ,  if ( 𝑃  ≤  𝐴 ,  𝐴 ,  𝑃 ) ,  𝑄 ) 〉 ) | 
						
							| 16 |  | eqid | ⊢ ( ( abs  ∘   −  )  ∘  𝐹 )  =  ( ( abs  ∘   −  )  ∘  𝐹 ) | 
						
							| 17 | 16 6 | ovolsf | ⊢ ( 𝐹 : ℕ ⟶ (  ≤   ∩  ( ℝ  ×  ℝ ) )  →  𝑆 : ℕ ⟶ ( 0 [,) +∞ ) ) | 
						
							| 18 | 9 17 | syl | ⊢ ( 𝜑  →  𝑆 : ℕ ⟶ ( 0 [,) +∞ ) ) | 
						
							| 19 | 18 | frnd | ⊢ ( 𝜑  →  ran  𝑆  ⊆  ( 0 [,) +∞ ) ) | 
						
							| 20 |  | icossxr | ⊢ ( 0 [,) +∞ )  ⊆  ℝ* | 
						
							| 21 | 19 20 | sstrdi | ⊢ ( 𝜑  →  ran  𝑆  ⊆  ℝ* ) | 
						
							| 22 |  | supxrcl | ⊢ ( ran  𝑆  ⊆  ℝ*  →  sup ( ran  𝑆 ,  ℝ* ,   <  )  ∈  ℝ* ) | 
						
							| 23 | 21 22 | syl | ⊢ ( 𝜑  →  sup ( ran  𝑆 ,  ℝ* ,   <  )  ∈  ℝ* ) | 
						
							| 24 | 5 | rpred | ⊢ ( 𝜑  →  𝐶  ∈  ℝ ) | 
						
							| 25 | 4 24 | readdcld | ⊢ ( 𝜑  →  ( ( vol* ‘ 𝐸 )  +  𝐶 )  ∈  ℝ ) | 
						
							| 26 |  | mnfxr | ⊢ -∞  ∈  ℝ* | 
						
							| 27 | 26 | a1i | ⊢ ( 𝜑  →  -∞  ∈  ℝ* ) | 
						
							| 28 | 18 | ffnd | ⊢ ( 𝜑  →  𝑆  Fn  ℕ ) | 
						
							| 29 |  | 1nn | ⊢ 1  ∈  ℕ | 
						
							| 30 |  | fnfvelrn | ⊢ ( ( 𝑆  Fn  ℕ  ∧  1  ∈  ℕ )  →  ( 𝑆 ‘ 1 )  ∈  ran  𝑆 ) | 
						
							| 31 | 28 29 30 | sylancl | ⊢ ( 𝜑  →  ( 𝑆 ‘ 1 )  ∈  ran  𝑆 ) | 
						
							| 32 | 21 31 | sseldd | ⊢ ( 𝜑  →  ( 𝑆 ‘ 1 )  ∈  ℝ* ) | 
						
							| 33 |  | rge0ssre | ⊢ ( 0 [,) +∞ )  ⊆  ℝ | 
						
							| 34 |  | ffvelcdm | ⊢ ( ( 𝑆 : ℕ ⟶ ( 0 [,) +∞ )  ∧  1  ∈  ℕ )  →  ( 𝑆 ‘ 1 )  ∈  ( 0 [,) +∞ ) ) | 
						
							| 35 | 18 29 34 | sylancl | ⊢ ( 𝜑  →  ( 𝑆 ‘ 1 )  ∈  ( 0 [,) +∞ ) ) | 
						
							| 36 | 33 35 | sselid | ⊢ ( 𝜑  →  ( 𝑆 ‘ 1 )  ∈  ℝ ) | 
						
							| 37 | 36 | mnfltd | ⊢ ( 𝜑  →  -∞  <  ( 𝑆 ‘ 1 ) ) | 
						
							| 38 |  | supxrub | ⊢ ( ( ran  𝑆  ⊆  ℝ*  ∧  ( 𝑆 ‘ 1 )  ∈  ran  𝑆 )  →  ( 𝑆 ‘ 1 )  ≤  sup ( ran  𝑆 ,  ℝ* ,   <  ) ) | 
						
							| 39 | 21 31 38 | syl2anc | ⊢ ( 𝜑  →  ( 𝑆 ‘ 1 )  ≤  sup ( ran  𝑆 ,  ℝ* ,   <  ) ) | 
						
							| 40 | 27 32 23 37 39 | xrltletrd | ⊢ ( 𝜑  →  -∞  <  sup ( ran  𝑆 ,  ℝ* ,   <  ) ) | 
						
							| 41 |  | xrre | ⊢ ( ( ( sup ( ran  𝑆 ,  ℝ* ,   <  )  ∈  ℝ*  ∧  ( ( vol* ‘ 𝐸 )  +  𝐶 )  ∈  ℝ )  ∧  ( -∞  <  sup ( ran  𝑆 ,  ℝ* ,   <  )  ∧  sup ( ran  𝑆 ,  ℝ* ,   <  )  ≤  ( ( vol* ‘ 𝐸 )  +  𝐶 ) ) )  →  sup ( ran  𝑆 ,  ℝ* ,   <  )  ∈  ℝ ) | 
						
							| 42 | 23 25 40 11 41 | syl22anc | ⊢ ( 𝜑  →  sup ( ran  𝑆 ,  ℝ* ,   <  )  ∈  ℝ ) |