Theorem salunicl 46502

Description: SAlg sigma-algebra is closed under countable union. (Contributed by Glauco Siliprandi, 17-Aug-2020.)

Hypotheses

Ref	Expression
salunicl.s	⊢ (𝜑 → 𝑆 ∈ SAlg)
salunicl.t	⊢ (𝜑 → 𝑇 ∈ 𝒫 𝑆)
salunicl.tct	⊢ (𝜑 → 𝑇 ≼ ω)

Assertion

Ref	Expression
salunicl	⊢ (𝜑 → ∪ 𝑇 ∈ 𝑆)

Proof of Theorem salunicl

Dummy variable 𝑦 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		salunicl.tct	. 2 ⊢ (𝜑 → 𝑇 ≼ ω)
2		breq1 5099	. . . 4 ⊢ (𝑦 = 𝑇 → (𝑦 ≼ ω ↔ 𝑇 ≼ ω))
3		unieq 4872	. . . . 5 ⊢ (𝑦 = 𝑇 → ∪ 𝑦 = ∪ 𝑇)
4	3	eleq1d 2819	. . . 4 ⊢ (𝑦 = 𝑇 → (∪ 𝑦 ∈ 𝑆 ↔ ∪ 𝑇 ∈ 𝑆))
5	2, 4	imbi12d 344	. . 3 ⊢ (𝑦 = 𝑇 → ((𝑦 ≼ ω → ∪ 𝑦 ∈ 𝑆) ↔ (𝑇 ≼ ω → ∪ 𝑇 ∈ 𝑆)))
6		salunicl.s	. . . . 5 ⊢ (𝜑 → 𝑆 ∈ SAlg)
7		issal 46500	. . . . . 6 ⊢ (𝑆 ∈ SAlg → (𝑆 ∈ SAlg ↔ (∅ ∈ 𝑆 ∧ ∀𝑦 ∈ 𝑆 (∪ 𝑆 ∖ 𝑦) ∈ 𝑆 ∧ ∀𝑦 ∈ 𝒫 𝑆(𝑦 ≼ ω → ∪ 𝑦 ∈ 𝑆))))
8	6, 7	syl 17	. . . . 5 ⊢ (𝜑 → (𝑆 ∈ SAlg ↔ (∅ ∈ 𝑆 ∧ ∀𝑦 ∈ 𝑆 (∪ 𝑆 ∖ 𝑦) ∈ 𝑆 ∧ ∀𝑦 ∈ 𝒫 𝑆(𝑦 ≼ ω → ∪ 𝑦 ∈ 𝑆))))
9	6, 8	mpbid 232	. . . 4 ⊢ (𝜑 → (∅ ∈ 𝑆 ∧ ∀𝑦 ∈ 𝑆 (∪ 𝑆 ∖ 𝑦) ∈ 𝑆 ∧ ∀𝑦 ∈ 𝒫 𝑆(𝑦 ≼ ω → ∪ 𝑦 ∈ 𝑆)))
10	9	simp3d 1144	. . 3 ⊢ (𝜑 → ∀𝑦 ∈ 𝒫 𝑆(𝑦 ≼ ω → ∪ 𝑦 ∈ 𝑆))
11		salunicl.t	. . 3 ⊢ (𝜑 → 𝑇 ∈ 𝒫 𝑆)
12	5, 10, 11	rspcdva 3575	. 2 ⊢ (𝜑 → (𝑇 ≼ ω → ∪ 𝑇 ∈ 𝑆))
13	1, 12	mpd 15	1 ⊢ (𝜑 → ∪ 𝑇 ∈ 𝑆)

Syntax hints:   → wi 4   ↔ wb 206   ∧ w3a 1086   = wceq 1541   ∈ wcel 2113  ∀wral 3049   ∖ cdif 3896  ∅c0 4283  𝒫 cpw 4552  ∪ cuni 4861   class class class wbr 5096  ωcom 7806   ≼ cdom 8879  SAlgcsalg 46494

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-8 2115  ax-9 2123  ax-ext 2706

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3an 1088  df-tru 1544  df-fal 1554  df-ex 1781  df-sb 2068  df-clab 2713  df-cleq 2726  df-clel 2809  df-ral 3050  df-rab 3398  df-v 3440  df-dif 3902  df-un 3904  df-ss 3916  df-nul 4284  df-if 4478  df-pw 4554  df-sn 4579  df-pr 4581  df-op 4585  df-uni 4862  df-br 5097  df-salg 46495

This theorem is referenced by:  saliunclf  46508  intsal  46516  smfpimbor1lem1  46984