Metamath Proof Explorer


Theorem sigainb

Description: Building a sigma-algebra from intersections with a given set. (Contributed by Thierry Arnoux, 26-Dec-2016)

Ref Expression
Assertion sigainb ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → ( 𝑆 ∩ 𝒫 𝐴 ) ∈ ( sigAlgebra ‘ 𝐴 ) )

Proof

Step Hyp Ref Expression
1 inex1g ⊢ ( 𝑆 ∈ ∪ ran sigAlgebra → ( 𝑆 ∩ 𝒫 𝐴 ) ∈ V )
2 1 adantr ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → ( 𝑆 ∩ 𝒫 𝐴 ) ∈ V )
3 inss2 ⊢ ( 𝑆 ∩ 𝒫 𝐴 ) ⊆ 𝒫 𝐴
4 3 a1i ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → ( 𝑆 ∩ 𝒫 𝐴 ) ⊆ 𝒫 𝐴 )
5 simpr ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → 𝐴 ∈ 𝑆 )
6 pwidg ⊢ ( 𝐴 ∈ 𝑆 → 𝐴 ∈ 𝒫 𝐴 )
7 5 6 syl ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → 𝐴 ∈ 𝒫 𝐴 )
8 5 7 elind ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → 𝐴 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) )
9 simpll ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) → 𝑆 ∈ ∪ ran sigAlgebra )
10 simplr ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) → 𝐴 ∈ 𝑆 )
11 inss1 ⊢ ( 𝑆 ∩ 𝒫 𝐴 ) ⊆ 𝑆
12 simpr ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) → 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) )
13 11 12 sselid ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) → 𝑥 ∈ 𝑆 )
14 difelsiga ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ∧ 𝑥 ∈ 𝑆 ) → ( 𝐴 ∖ 𝑥 ) ∈ 𝑆 )
15 9 10 13 14 syl3anc ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) → ( 𝐴 ∖ 𝑥 ) ∈ 𝑆 )
16 difss ⊢ ( 𝐴 ∖ 𝑥 ) ⊆ 𝐴
17 elpwg ⊢ ( ( 𝐴 ∖ 𝑥 ) ∈ 𝑆 → ( ( 𝐴 ∖ 𝑥 ) ∈ 𝒫 𝐴 ↔ ( 𝐴 ∖ 𝑥 ) ⊆ 𝐴 ) )
18 16 17 mpbiri ⊢ ( ( 𝐴 ∖ 𝑥 ) ∈ 𝑆 → ( 𝐴 ∖ 𝑥 ) ∈ 𝒫 𝐴 )
19 15 18 syl ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) → ( 𝐴 ∖ 𝑥 ) ∈ 𝒫 𝐴 )
20 15 19 elind ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) → ( 𝐴 ∖ 𝑥 ) ∈ ( 𝑆 ∩ 𝒫 𝐴 ) )
21 20 ralrimiva ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → ∀ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝐴 ∖ 𝑥 ) ∈ ( 𝑆 ∩ 𝒫 𝐴 ) )
22 simplll ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → 𝑆 ∈ ∪ ran sigAlgebra )
23 simplr ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) )
24 elpwi ⊢ ( 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) → 𝑥 ⊆ ( 𝑆 ∩ 𝒫 𝐴 ) )
25 sstr ⊢ ( ( 𝑥 ⊆ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ( 𝑆 ∩ 𝒫 𝐴 ) ⊆ 𝑆 ) → 𝑥 ⊆ 𝑆 )
26 11 25 mpan2 ⊢ ( 𝑥 ⊆ ( 𝑆 ∩ 𝒫 𝐴 ) → 𝑥 ⊆ 𝑆 )
27 23 24 26 3syl ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → 𝑥 ⊆ 𝑆 )
28 elpwg ⊢ ( 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) → ( 𝑥 ∈ 𝒫 𝑆 ↔ 𝑥 ⊆ 𝑆 ) )
29 28 biimpar ⊢ ( ( 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ∧ 𝑥 ⊆ 𝑆 ) → 𝑥 ∈ 𝒫 𝑆 )
30 23 27 29 syl2anc ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → 𝑥 ∈ 𝒫 𝑆 )
31 simpr ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → 𝑥 ≼ ω )
32 sigaclcu ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝑥 ∈ 𝒫 𝑆 ∧ 𝑥 ≼ ω ) → ∪ 𝑥 ∈ 𝑆 )
33 22 30 31 32 syl3anc ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → ∪ 𝑥 ∈ 𝑆 )
34 sstr ⊢ ( ( 𝑥 ⊆ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ( 𝑆 ∩ 𝒫 𝐴 ) ⊆ 𝒫 𝐴 ) → 𝑥 ⊆ 𝒫 𝐴 )
35 3 34 mpan2 ⊢ ( 𝑥 ⊆ ( 𝑆 ∩ 𝒫 𝐴 ) → 𝑥 ⊆ 𝒫 𝐴 )
36 23 24 35 3syl ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → 𝑥 ⊆ 𝒫 𝐴 )
37 sspwuni ⊢ ( 𝑥 ⊆ 𝒫 𝐴 ↔ ∪ 𝑥 ⊆ 𝐴 )
38 vuniex ⊢ ∪ 𝑥 ∈ V
39 38 elpw ⊢ ( ∪ 𝑥 ∈ 𝒫 𝐴 ↔ ∪ 𝑥 ⊆ 𝐴 )
40 37 39 bitr4i ⊢ ( 𝑥 ⊆ 𝒫 𝐴 ↔ ∪ 𝑥 ∈ 𝒫 𝐴 )
41 36 40 sylib ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → ∪ 𝑥 ∈ 𝒫 𝐴 )
42 33 41 elind ⊢ ( ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) ∧ 𝑥 ≼ ω ) → ∪ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) )
43 42 ex ⊢ ( ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) ∧ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ) → ( 𝑥 ≼ ω → ∪ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) )
44 43 ralrimiva ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → ∀ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝑥 ≼ ω → ∪ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) )
45 8 21 44 3jca ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → ( 𝐴 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ∀ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝐴 ∖ 𝑥 ) ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ∀ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝑥 ≼ ω → ∪ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) ) )
46 issiga ⊢ ( ( 𝑆 ∩ 𝒫 𝐴 ) ∈ V → ( ( 𝑆 ∩ 𝒫 𝐴 ) ∈ ( sigAlgebra ‘ 𝐴 ) ↔ ( ( 𝑆 ∩ 𝒫 𝐴 ) ⊆ 𝒫 𝐴 ∧ ( 𝐴 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ∀ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝐴 ∖ 𝑥 ) ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ∀ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝑥 ≼ ω → ∪ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) ) ) ) )
47 46 biimpar ⊢ ( ( ( 𝑆 ∩ 𝒫 𝐴 ) ∈ V ∧ ( ( 𝑆 ∩ 𝒫 𝐴 ) ⊆ 𝒫 𝐴 ∧ ( 𝐴 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ∀ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝐴 ∖ 𝑥 ) ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ∧ ∀ 𝑥 ∈ 𝒫 ( 𝑆 ∩ 𝒫 𝐴 ) ( 𝑥 ≼ ω → ∪ 𝑥 ∈ ( 𝑆 ∩ 𝒫 𝐴 ) ) ) ) ) → ( 𝑆 ∩ 𝒫 𝐴 ) ∈ ( sigAlgebra ‘ 𝐴 ) )
48 2 4 45 47 syl12anc ⊢ ( ( 𝑆 ∈ ∪ ran sigAlgebra ∧ 𝐴 ∈ 𝑆 ) → ( 𝑆 ∩ 𝒫 𝐴 ) ∈ ( sigAlgebra ‘ 𝐴 ) )