Theorem smfpreimalt 47253

Description: Given a function measurable w.r.t. to a sigma-algebra, the preimage of an open interval unbounded below is in the subspace sigma-algebra induced by its domain. (Contributed by Glauco Siliprandi, 26-Jun-2021.)

Hypotheses

Ref	Expression
smfpreimalt.s	⊢ (𝜑 → 𝑆 ∈ SAlg)
smfpreimalt.f	⊢ (𝜑 → 𝐹 ∈ (SMblFn‘𝑆))
smfpreimalt.d	⊢ 𝐷 = dom 𝐹
smfpreimalt.a	⊢ (𝜑 → 𝐴 ∈ ℝ)

Assertion

Ref	Expression
smfpreimalt	⊢ (𝜑 → {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝐴} ∈ (𝑆 ↾t 𝐷))

Distinct variable groups:   𝑥,𝐴   𝑥,𝐷   𝑥,𝐹

Allowed substitution hints:   𝜑(𝑥)   𝑆(𝑥)

Proof of Theorem smfpreimalt

Dummy variable 𝑎 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		smfpreimalt.a	. 2 ⊢ (𝜑 → 𝐴 ∈ ℝ)
2		smfpreimalt.f	. . . 4 ⊢ (𝜑 → 𝐹 ∈ (SMblFn‘𝑆))
3		smfpreimalt.s	. . . . 5 ⊢ (𝜑 → 𝑆 ∈ SAlg)
4		smfpreimalt.d	. . . . 5 ⊢ 𝐷 = dom 𝐹
5	3, 4	issmf 47250	. . . 4 ⊢ (𝜑 → (𝐹 ∈ (SMblFn‘𝑆) ↔ (𝐷 ⊆ ∪ 𝑆 ∧ 𝐹:𝐷⟶ℝ ∧ ∀𝑎 ∈ ℝ {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝑎} ∈ (𝑆 ↾t 𝐷))))
6	2, 5	mpbid 234	. . 3 ⊢ (𝜑 → (𝐷 ⊆ ∪ 𝑆 ∧ 𝐹:𝐷⟶ℝ ∧ ∀𝑎 ∈ ℝ {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝑎} ∈ (𝑆 ↾t 𝐷)))
7	6	simp3d 1153	. 2 ⊢ (𝜑 → ∀𝑎 ∈ ℝ {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝑎} ∈ (𝑆 ↾t 𝐷))
8		breq2 5098	. . . . 5 ⊢ (𝑎 = 𝐴 → ((𝐹‘𝑥) < 𝑎 ↔ (𝐹‘𝑥) < 𝐴))
9	8	rabbidv 3415	. . . 4 ⊢ (𝑎 = 𝐴 → {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝑎} = {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝐴})
10	9	eleq1d 2841	. . 3 ⊢ (𝑎 = 𝐴 → ({𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝑎} ∈ (𝑆 ↾t 𝐷) ↔ {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝐴} ∈ (𝑆 ↾t 𝐷)))
11	10	rspcva 3574	. 2 ⊢ ((𝐴 ∈ ℝ ∧ ∀𝑎 ∈ ℝ {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝑎} ∈ (𝑆 ↾t 𝐷)) → {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝐴} ∈ (𝑆 ↾t 𝐷))
12	1, 7, 11	syl2anc 592	1 ⊢ (𝜑 → {𝑥 ∈ 𝐷 ∣ (𝐹‘𝑥) < 𝐴} ∈ (𝑆 ↾t 𝐷))

Syntax hints:   → wi 4   ∧ w3a 1095   = wceq 1554   ∈ wcel 2136  ∀wral 3070  {crab 3408   ⊆ wss 3899  ∪ cuni 4859   class class class wbr 5094  dom cdm 5640  ⟶wf 6506  ‘cfv 6510  (class class class)co 7385  ℝcr 11062   < clt 11206   ↾_t crest 17425  SAlgcsalg 46830  SMblFncsmblfn 47217

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1809  ax-4 1823  ax-5 1924  ax-6 1981  ax-7 2022  ax-8 2138  ax-9 2146  ax-10 2169  ax-11 2185  ax-12 2206  ax-ext 2728  ax-sep 5240  ax-nul 5250  ax-pow 5316  ax-pr 5384  ax-un 7707  ax-cnex 11119  ax-resscn 11120  ax-pre-lttri 11137  ax-pre-lttrn 11138

This theorem depends on definitions:  df-bi 209  df-an 399  df-or 857  df-3or 1096  df-3an 1097  df-tru 1557  df-fal 1567  df-ex 1794  df-nf 1798  df-sb 2085  df-mo 2560  df-eu 2590  df-clab 2735  df-cleq 2748  df-clel 2831  df-nfc 2905  df-ne 2952  df-nel 3056  df-ral 3071  df-rex 3081  df-rab 3409  df-v 3450  df-sbc 3740  df-csb 3848  df-dif 3902  df-un 3904  df-in 3906  df-ss 3916  df-nul 4281  df-if 4475  df-pw 4551  df-sn 4577  df-pr 4579  df-op 4583  df-uni 4860  df-iun 4945  df-br 5095  df-opab 5157  df-mpt 5176  df-id 5535  df-po 5548  df-so 5549  df-xp 5646  df-rel 5647  df-cnv 5648  df-co 5649  df-dm 5650  df-rn 5651  df-res 5652  df-ima 5653  df-iota 6466  df-fun 6512  df-fn 6513  df-f 6514  df-f1 6515  df-fo 6516  df-f1o 6517  df-fv 6518  df-ov 7388  df-oprab 7389  df-mpo 7390  df-1st 7959  df-2nd 7960  df-er 8666  df-pm 8799  df-en 8917  df-dom 8918  df-sdom 8919  df-pnf 11208  df-mnf 11209  df-xr 11210  df-ltxr 11211  df-le 11212  df-ioo 13343  df-ico 13345  df-smblfn 47218

This theorem is referenced by:  sssmf  47260  smfsssmf  47265  issmfle  47267  smflimlem6  47298  smfco  47324