Metamath Proof Explorer


Theorem smfsupmpt

Description: The supremum of a countable set of sigma-measurable functions is sigma-measurable. Proposition 121F (b) of Fremlin1 p. 38 . (Contributed by Glauco Siliprandi, 23-Oct-2021)

Ref Expression
Hypotheses smfsupmpt.n 𝑛 𝜑
smfsupmpt.x 𝑥 𝜑
smfsupmpt.y 𝑦 𝜑
smfsupmpt.m ( 𝜑𝑀 ∈ ℤ )
smfsupmpt.z 𝑍 = ( ℤ𝑀 )
smfsupmpt.s ( 𝜑𝑆 ∈ SAlg )
smfsupmpt.b ( ( 𝜑𝑛𝑍𝑥𝐴 ) → 𝐵𝑉 )
smfsupmpt.f ( ( 𝜑𝑛𝑍 ) → ( 𝑥𝐴𝐵 ) ∈ ( SMblFn ‘ 𝑆 ) )
smfsupmpt.d 𝐷 = { 𝑥 𝑛𝑍 𝐴 ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 }
smfsupmpt.g 𝐺 = ( 𝑥𝐷 ↦ sup ( ran ( 𝑛𝑍𝐵 ) , ℝ , < ) )
Assertion smfsupmpt ( 𝜑𝐺 ∈ ( SMblFn ‘ 𝑆 ) )

Proof

Step Hyp Ref Expression
1 smfsupmpt.n 𝑛 𝜑
2 smfsupmpt.x 𝑥 𝜑
3 smfsupmpt.y 𝑦 𝜑
4 smfsupmpt.m ( 𝜑𝑀 ∈ ℤ )
5 smfsupmpt.z 𝑍 = ( ℤ𝑀 )
6 smfsupmpt.s ( 𝜑𝑆 ∈ SAlg )
7 smfsupmpt.b ( ( 𝜑𝑛𝑍𝑥𝐴 ) → 𝐵𝑉 )
8 smfsupmpt.f ( ( 𝜑𝑛𝑍 ) → ( 𝑥𝐴𝐵 ) ∈ ( SMblFn ‘ 𝑆 ) )
9 smfsupmpt.d 𝐷 = { 𝑥 𝑛𝑍 𝐴 ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 }
10 smfsupmpt.g 𝐺 = ( 𝑥𝐷 ↦ sup ( ran ( 𝑛𝑍𝐵 ) , ℝ , < ) )
11 eqidd ( 𝜑 → ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) = ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) )
12 11 8 fvmpt2d ( ( 𝜑𝑛𝑍 ) → ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) = ( 𝑥𝐴𝐵 ) )
13 12 dmeqd ( ( 𝜑𝑛𝑍 ) → dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) = dom ( 𝑥𝐴𝐵 ) )
14 nfcv 𝑥 𝑍
15 14 nfcri 𝑥 𝑛𝑍
16 2 15 nfan 𝑥 ( 𝜑𝑛𝑍 )
17 eqid ( 𝑥𝐴𝐵 ) = ( 𝑥𝐴𝐵 )
18 7 3expa ( ( ( 𝜑𝑛𝑍 ) ∧ 𝑥𝐴 ) → 𝐵𝑉 )
19 16 17 18 dmmptdf ( ( 𝜑𝑛𝑍 ) → dom ( 𝑥𝐴𝐵 ) = 𝐴 )
20 13 19 eqtr2d ( ( 𝜑𝑛𝑍 ) → 𝐴 = dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) )
21 1 20 iineq2d ( 𝜑 𝑛𝑍 𝐴 = 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) )
22 nfcv 𝑥 𝑛𝑍 𝐴
23 nfmpt1 𝑥 ( 𝑥𝐴𝐵 )
24 14 23 nfmpt 𝑥 ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) )
25 nfcv 𝑥 𝑛
26 24 25 nffv 𝑥 ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 )
27 26 nfdm 𝑥 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 )
28 14 27 nfiin 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 )
29 22 28 rabeqf ( 𝑛𝑍 𝐴 = 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) → { 𝑥 𝑛𝑍 𝐴 ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 } = { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 } )
30 21 29 syl ( 𝜑 → { 𝑥 𝑛𝑍 𝐴 ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 } = { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 } )
31 nfv 𝑦 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 )
32 3 31 nfan 𝑦 ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) )
33 nfii1 𝑛 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 )
34 33 nfcri 𝑛 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 )
35 1 34 nfan 𝑛 ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) )
36 simpll ( ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) ∧ 𝑛𝑍 ) → 𝜑 )
37 simpr ( ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) ∧ 𝑛𝑍 ) → 𝑛𝑍 )
38 eliinid ( ( 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∧ 𝑛𝑍 ) → 𝑥 ∈ dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) )
39 38 adantll ( ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) ∧ 𝑛𝑍 ) → 𝑥 ∈ dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) )
40 13 19 eqtrd ( ( 𝜑𝑛𝑍 ) → dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) = 𝐴 )
41 40 adantlr ( ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) ∧ 𝑛𝑍 ) → dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) = 𝐴 )
42 39 41 eleqtrd ( ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) ∧ 𝑛𝑍 ) → 𝑥𝐴 )
43 12 fveq1d ( ( 𝜑𝑛𝑍 ) → ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) = ( ( 𝑥𝐴𝐵 ) ‘ 𝑥 ) )
44 43 3adant3 ( ( 𝜑𝑛𝑍𝑥𝐴 ) → ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) = ( ( 𝑥𝐴𝐵 ) ‘ 𝑥 ) )
45 simp3 ( ( 𝜑𝑛𝑍𝑥𝐴 ) → 𝑥𝐴 )
46 fvmpt4 ( ( 𝑥𝐴𝐵𝑉 ) → ( ( 𝑥𝐴𝐵 ) ‘ 𝑥 ) = 𝐵 )
47 45 7 46 syl2anc ( ( 𝜑𝑛𝑍𝑥𝐴 ) → ( ( 𝑥𝐴𝐵 ) ‘ 𝑥 ) = 𝐵 )
48 44 47 eqtr2d ( ( 𝜑𝑛𝑍𝑥𝐴 ) → 𝐵 = ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) )
49 48 breq1d ( ( 𝜑𝑛𝑍𝑥𝐴 ) → ( 𝐵𝑦 ↔ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 ) )
50 36 37 42 49 syl3anc ( ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) ∧ 𝑛𝑍 ) → ( 𝐵𝑦 ↔ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 ) )
51 35 50 ralbida ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) → ( ∀ 𝑛𝑍 𝐵𝑦 ↔ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 ) )
52 32 51 rexbid ( ( 𝜑𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ) → ( ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 ↔ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 ) )
53 2 52 rabbida ( 𝜑 → { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 } = { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } )
54 30 53 eqtrd ( 𝜑 → { 𝑥 𝑛𝑍 𝐴 ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 } = { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } )
55 9 54 syl5eq ( 𝜑𝐷 = { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } )
56 nfcv 𝑛
57 nfra1 𝑛𝑛𝑍 𝐵𝑦
58 56 57 nfrex 𝑛𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦
59 nfii1 𝑛 𝑛𝑍 𝐴
60 58 59 nfrabw 𝑛 { 𝑥 𝑛𝑍 𝐴 ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 }
61 9 60 nfcxfr 𝑛 𝐷
62 61 nfcri 𝑛 𝑥𝐷
63 1 62 nfan 𝑛 ( 𝜑𝑥𝐷 )
64 simpll ( ( ( 𝜑𝑥𝐷 ) ∧ 𝑛𝑍 ) → 𝜑 )
65 simpr ( ( ( 𝜑𝑥𝐷 ) ∧ 𝑛𝑍 ) → 𝑛𝑍 )
66 rabidim1 ( 𝑥 ∈ { 𝑥 𝑛𝑍 𝐴 ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 𝐵𝑦 } → 𝑥 𝑛𝑍 𝐴 )
67 66 9 eleq2s ( 𝑥𝐷𝑥 𝑛𝑍 𝐴 )
68 eliinid ( ( 𝑥 𝑛𝑍 𝐴𝑛𝑍 ) → 𝑥𝐴 )
69 67 68 sylan ( ( 𝑥𝐷𝑛𝑍 ) → 𝑥𝐴 )
70 69 adantll ( ( ( 𝜑𝑥𝐷 ) ∧ 𝑛𝑍 ) → 𝑥𝐴 )
71 64 65 70 48 syl3anc ( ( ( 𝜑𝑥𝐷 ) ∧ 𝑛𝑍 ) → 𝐵 = ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) )
72 63 71 mpteq2da ( ( 𝜑𝑥𝐷 ) → ( 𝑛𝑍𝐵 ) = ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) )
73 72 rneqd ( ( 𝜑𝑥𝐷 ) → ran ( 𝑛𝑍𝐵 ) = ran ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) )
74 73 supeq1d ( ( 𝜑𝑥𝐷 ) → sup ( ran ( 𝑛𝑍𝐵 ) , ℝ , < ) = sup ( ran ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) , ℝ , < ) )
75 2 55 74 mpteq12da ( 𝜑 → ( 𝑥𝐷 ↦ sup ( ran ( 𝑛𝑍𝐵 ) , ℝ , < ) ) = ( 𝑥 ∈ { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } ↦ sup ( ran ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) , ℝ , < ) ) )
76 10 75 syl5eq ( 𝜑𝐺 = ( 𝑥 ∈ { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } ↦ sup ( ran ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) , ℝ , < ) ) )
77 nfmpt1 𝑛 ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) )
78 1 8 fmptd2f ( 𝜑 → ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) : 𝑍 ⟶ ( SMblFn ‘ 𝑆 ) )
79 eqid { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } = { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 }
80 eqid ( 𝑥 ∈ { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } ↦ sup ( ran ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) , ℝ , < ) ) = ( 𝑥 ∈ { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } ↦ sup ( ran ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) , ℝ , < ) )
81 77 24 4 5 6 78 79 80 smfsup ( 𝜑 → ( 𝑥 ∈ { 𝑥 𝑛𝑍 dom ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ∣ ∃ 𝑦 ∈ ℝ ∀ 𝑛𝑍 ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ≤ 𝑦 } ↦ sup ( ran ( 𝑛𝑍 ↦ ( ( ( 𝑛𝑍 ↦ ( 𝑥𝐴𝐵 ) ) ‘ 𝑛 ) ‘ 𝑥 ) ) , ℝ , < ) ) ∈ ( SMblFn ‘ 𝑆 ) )
82 76 81 eqeltrd ( 𝜑𝐺 ∈ ( SMblFn ‘ 𝑆 ) )