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Theorem disjxun0 32072
Description: Simplify a disjoint union. (Contributed by Thierry Arnoux, 27-Nov-2023.)
Hypothesis
Ref Expression
disjxun0.1 ((𝜑𝑥𝐵) → 𝐶 = ∅)
Assertion
Ref Expression
disjxun0 (𝜑 → (Disj 𝑥 ∈ (𝐴𝐵)𝐶Disj 𝑥𝐴 𝐶))
Distinct variable group:   𝜑,𝑥
Allowed substitution hints:   𝐴(𝑥)   𝐵(𝑥)   𝐶(𝑥)

Proof of Theorem disjxun0
Dummy variable 𝑦 is distinct from all other variables.
StepHypRef Expression
1 disjxun0.1 . . . . 5 ((𝜑𝑥𝐵) → 𝐶 = ∅)
2 nel02 4331 . . . . 5 (𝐶 = ∅ → ¬ 𝑦𝐶)
31, 2syl 17 . . . 4 ((𝜑𝑥𝐵) → ¬ 𝑦𝐶)
43rmounid 32002 . . 3 (𝜑 → (∃*𝑥 ∈ (𝐴𝐵)𝑦𝐶 ↔ ∃*𝑥𝐴 𝑦𝐶))
54albidv 1921 . 2 (𝜑 → (∀𝑦∃*𝑥 ∈ (𝐴𝐵)𝑦𝐶 ↔ ∀𝑦∃*𝑥𝐴 𝑦𝐶))
6 df-disj 5113 . 2 (Disj 𝑥 ∈ (𝐴𝐵)𝐶 ↔ ∀𝑦∃*𝑥 ∈ (𝐴𝐵)𝑦𝐶)
7 df-disj 5113 . 2 (Disj 𝑥𝐴 𝐶 ↔ ∀𝑦∃*𝑥𝐴 𝑦𝐶)
85, 6, 73bitr4g 313 1 (𝜑 → (Disj 𝑥 ∈ (𝐴𝐵)𝐶Disj 𝑥𝐴 𝐶))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 205  wa 394  wal 1537   = wceq 1539  wcel 2104  ∃*wrmo 3373  cun 3945  c0 4321  Disj wdisj 5112
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1911  ax-6 1969  ax-7 2009  ax-8 2106  ax-9 2114  ax-ext 2701
This theorem depends on definitions:  df-bi 206  df-an 395  df-or 844  df-tru 1542  df-fal 1552  df-ex 1780  df-sb 2066  df-mo 2532  df-clab 2708  df-cleq 2722  df-clel 2808  df-rmo 3374  df-v 3474  df-dif 3950  df-un 3952  df-nul 4322  df-disj 5113
This theorem is referenced by:  tocyccntz  32573
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