Metamath Proof Explorer


Theorem ovolsplit

Description: The Lebesgue outer measure function is finitely sub-additive: application to a set split in two parts, using addition for extended reals. (Contributed by Glauco Siliprandi, 3-Mar-2021)

Ref Expression
Hypothesis ovolsplit.1 ( 𝜑𝐴 ⊆ ℝ )
Assertion ovolsplit ( 𝜑 → ( vol* ‘ 𝐴 ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )

Proof

Step Hyp Ref Expression
1 ovolsplit.1 ( 𝜑𝐴 ⊆ ℝ )
2 inundif ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) = 𝐴
3 2 eqcomi 𝐴 = ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) )
4 3 a1i ( 𝜑𝐴 = ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) )
5 4 fveq2d ( 𝜑 → ( vol* ‘ 𝐴 ) = ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) )
6 1 ssinss1d ( 𝜑 → ( 𝐴𝐵 ) ⊆ ℝ )
7 1 ssdifssd ( 𝜑 → ( 𝐴𝐵 ) ⊆ ℝ )
8 6 7 unssd ( 𝜑 → ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ⊆ ℝ )
9 ovolcl ( ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ⊆ ℝ → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ∈ ℝ* )
10 8 9 syl ( 𝜑 → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ∈ ℝ* )
11 pnfge ( ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ∈ ℝ* → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ +∞ )
12 10 11 syl ( 𝜑 → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ +∞ )
13 12 adantr ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ +∞ )
14 oveq1 ( ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) = ( +∞ +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
15 14 adantl ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) = ( +∞ +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
16 ovolcl ( ( 𝐴𝐵 ) ⊆ ℝ → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ* )
17 7 16 syl ( 𝜑 → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ* )
18 17 adantr ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ* )
19 reex ℝ ∈ V
20 19 a1i ( 𝜑 → ℝ ∈ V )
21 20 1 ssexd ( 𝜑𝐴 ∈ V )
22 difexg ( 𝐴 ∈ V → ( 𝐴𝐵 ) ∈ V )
23 21 22 syl ( 𝜑 → ( 𝐴𝐵 ) ∈ V )
24 elpwg ( ( 𝐴𝐵 ) ∈ V → ( ( 𝐴𝐵 ) ∈ 𝒫 ℝ ↔ ( 𝐴𝐵 ) ⊆ ℝ ) )
25 23 24 syl ( 𝜑 → ( ( 𝐴𝐵 ) ∈ 𝒫 ℝ ↔ ( 𝐴𝐵 ) ⊆ ℝ ) )
26 7 25 mpbird ( 𝜑 → ( 𝐴𝐵 ) ∈ 𝒫 ℝ )
27 ovolf vol* : 𝒫 ℝ ⟶ ( 0 [,] +∞ )
28 27 ffvelrni ( ( 𝐴𝐵 ) ∈ 𝒫 ℝ → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) )
29 26 28 syl ( 𝜑 → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) )
30 29 xrge0nemnfd ( 𝜑 → ( vol* ‘ ( 𝐴𝐵 ) ) ≠ -∞ )
31 30 adantr ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ≠ -∞ )
32 xaddpnf2 ( ( ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ* ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ≠ -∞ ) → ( +∞ +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) = +∞ )
33 18 31 32 syl2anc ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( +∞ +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) = +∞ )
34 15 33 eqtr2d ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → +∞ = ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
35 13 34 breqtrd ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
36 simpl ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → 𝜑 )
37 20 6 sselpwd ( 𝜑 → ( 𝐴𝐵 ) ∈ 𝒫 ℝ )
38 27 ffvelrni ( ( 𝐴𝐵 ) ∈ 𝒫 ℝ → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) )
39 37 38 syl ( 𝜑 → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) )
40 39 adantr ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) )
41 neqne ( ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ → ( vol* ‘ ( 𝐴𝐵 ) ) ≠ +∞ )
42 41 adantl ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ≠ +∞ )
43 ge0xrre ( ( ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ≠ +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
44 40 42 43 syl2anc ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
45 12 adantr ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ +∞ )
46 oveq2 ( ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) = ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 +∞ ) )
47 46 adantl ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) = ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 +∞ ) )
48 ovolcl ( ( 𝐴𝐵 ) ⊆ ℝ → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ* )
49 6 48 syl ( 𝜑 → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ* )
50 39 xrge0nemnfd ( 𝜑 → ( vol* ‘ ( 𝐴𝐵 ) ) ≠ -∞ )
51 xaddpnf1 ( ( ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ* ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ≠ -∞ ) → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 +∞ ) = +∞ )
52 49 50 51 syl2anc ( 𝜑 → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 +∞ ) = +∞ )
53 52 adantr ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 +∞ ) = +∞ )
54 47 53 eqtr2d ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → +∞ = ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
55 45 54 breqtrd ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
56 55 adantlr ( ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) ∧ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
57 simpll ( ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → 𝜑 )
58 simplr ( ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
59 29 adantr ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) )
60 neqne ( ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ → ( vol* ‘ ( 𝐴𝐵 ) ) ≠ +∞ )
61 60 adantl ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ≠ +∞ )
62 ge0xrre ( ( ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ( 0 [,] +∞ ) ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ≠ +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
63 59 61 62 syl2anc ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
64 63 adantlr ( ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
65 6 3ad2ant1 ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( 𝐴𝐵 ) ⊆ ℝ )
66 simp2 ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
67 7 3ad2ant1 ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( 𝐴𝐵 ) ⊆ ℝ )
68 simp3 ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ )
69 ovolun ( ( ( ( 𝐴𝐵 ) ⊆ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) ∧ ( ( 𝐴𝐵 ) ⊆ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) + ( vol* ‘ ( 𝐴𝐵 ) ) ) )
70 65 66 67 68 69 syl22anc ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) + ( vol* ‘ ( 𝐴𝐵 ) ) ) )
71 rexadd ( ( ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) = ( ( vol* ‘ ( 𝐴𝐵 ) ) + ( vol* ‘ ( 𝐴𝐵 ) ) ) )
72 71 eqcomd ( ( ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( ( vol* ‘ ( 𝐴𝐵 ) ) + ( vol* ‘ ( 𝐴𝐵 ) ) ) = ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
73 72 3adant1 ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( ( vol* ‘ ( 𝐴𝐵 ) ) + ( vol* ‘ ( 𝐴𝐵 ) ) ) = ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
74 70 73 breqtrd ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
75 57 58 64 74 syl3anc ( ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
76 56 75 pm2.61dan ( ( 𝜑 ∧ ( vol* ‘ ( 𝐴𝐵 ) ) ∈ ℝ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
77 36 44 76 syl2anc ( ( 𝜑 ∧ ¬ ( vol* ‘ ( 𝐴𝐵 ) ) = +∞ ) → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
78 35 77 pm2.61dan ( 𝜑 → ( vol* ‘ ( ( 𝐴𝐵 ) ∪ ( 𝐴𝐵 ) ) ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )
79 5 78 eqbrtrd ( 𝜑 → ( vol* ‘ 𝐴 ) ≤ ( ( vol* ‘ ( 𝐴𝐵 ) ) +𝑒 ( vol* ‘ ( 𝐴𝐵 ) ) ) )