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Theorem elrestd 38322
Description: A sufficient condition for being an open set of a subspace topology. (Contributed by Glauco Siliprandi, 26-Jun-2021.)
Hypotheses
Ref Expression
elrestd.1 (𝜑𝐽𝑉)
elrestd.2 (𝜑𝐵𝑊)
elrestd.3 (𝜑𝑋𝐽)
elrestd.4 𝐴 = (𝑋𝐵)
Assertion
Ref Expression
elrestd (𝜑𝐴 ∈ (𝐽t 𝐵))

Proof of Theorem elrestd
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 elrestd.3 . . 3 (𝜑𝑋𝐽)
2 elrestd.4 . . . 4 𝐴 = (𝑋𝐵)
32a1i 11 . . 3 (𝜑𝐴 = (𝑋𝐵))
4 ineq1 3769 . . . . 5 (𝑥 = 𝑋 → (𝑥𝐵) = (𝑋𝐵))
54eqeq2d 2620 . . . 4 (𝑥 = 𝑋 → (𝐴 = (𝑥𝐵) ↔ 𝐴 = (𝑋𝐵)))
65rspcev 3282 . . 3 ((𝑋𝐽𝐴 = (𝑋𝐵)) → ∃𝑥𝐽 𝐴 = (𝑥𝐵))
71, 3, 6syl2anc 691 . 2 (𝜑 → ∃𝑥𝐽 𝐴 = (𝑥𝐵))
8 elrestd.1 . . 3 (𝜑𝐽𝑉)
9 elrestd.2 . . 3 (𝜑𝐵𝑊)
10 elrest 15911 . . 3 ((𝐽𝑉𝐵𝑊) → (𝐴 ∈ (𝐽t 𝐵) ↔ ∃𝑥𝐽 𝐴 = (𝑥𝐵)))
118, 9, 10syl2anc 691 . 2 (𝜑 → (𝐴 ∈ (𝐽t 𝐵) ↔ ∃𝑥𝐽 𝐴 = (𝑥𝐵)))
127, 11mpbird 246 1 (𝜑𝐴 ∈ (𝐽t 𝐵))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 195   = wceq 1475  wcel 1977  wrex 2897  cin 3539  (class class class)co 6549  t crest 15904
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-rep 4699  ax-sep 4709  ax-nul 4717  ax-pr 4833  ax-un 6847
This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ne 2782  df-ral 2901  df-rex 2902  df-reu 2903  df-rab 2905  df-v 3175  df-sbc 3403  df-csb 3500  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-if 4037  df-sn 4126  df-pr 4128  df-op 4132  df-uni 4373  df-iun 4457  df-br 4584  df-opab 4644  df-mpt 4645  df-id 4953  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-rn 5049  df-res 5050  df-ima 5051  df-iota 5768  df-fun 5806  df-fn 5807  df-f 5808  df-f1 5809  df-fo 5810  df-f1o 5811  df-fv 5812  df-ov 6552  df-oprab 6553  df-mpt2 6554  df-rest 15906
This theorem is referenced by:  restuni3  38333  subsaliuncl  39252  subsalsal  39253  sssmf  39625  mbfresmf  39626  smfconst  39636  smflimlem1  39657  smfres  39675  smfco  39687
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