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Theorem exdistrf 2364
 Description: Distribution of existential quantifiers, with a bound-variable hypothesis saying that 𝑦 is not free in 𝜑, but 𝑥 can be free in 𝜑 (and there is no distinct variable condition on 𝑥 and 𝑦). (Contributed by Mario Carneiro, 20-Mar-2013.) (Proof shortened by Wolf Lammen, 14-May-2018.)
Hypothesis
Ref Expression
exdistrf.1 (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑦𝜑)
Assertion
Ref Expression
exdistrf (∃𝑥𝑦(𝜑𝜓) → ∃𝑥(𝜑 ∧ ∃𝑦𝜓))

Proof of Theorem exdistrf
StepHypRef Expression
1 nfe1 2067 . 2 𝑥𝑥(𝜑 ∧ ∃𝑦𝜓)
2 19.8a 2090 . . . . . 6 (𝜓 → ∃𝑦𝜓)
32anim2i 592 . . . . 5 ((𝜑𝜓) → (𝜑 ∧ ∃𝑦𝜓))
43eximi 1802 . . . 4 (∃𝑦(𝜑𝜓) → ∃𝑦(𝜑 ∧ ∃𝑦𝜓))
5 biidd 252 . . . . 5 (∀𝑥 𝑥 = 𝑦 → ((𝜑 ∧ ∃𝑦𝜓) ↔ (𝜑 ∧ ∃𝑦𝜓)))
65drex1 2358 . . . 4 (∀𝑥 𝑥 = 𝑦 → (∃𝑥(𝜑 ∧ ∃𝑦𝜓) ↔ ∃𝑦(𝜑 ∧ ∃𝑦𝜓)))
74, 6syl5ibr 236 . . 3 (∀𝑥 𝑥 = 𝑦 → (∃𝑦(𝜑𝜓) → ∃𝑥(𝜑 ∧ ∃𝑦𝜓)))
8 19.40 1837 . . . 4 (∃𝑦(𝜑𝜓) → (∃𝑦𝜑 ∧ ∃𝑦𝜓))
9 exdistrf.1 . . . . . 6 (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑦𝜑)
10919.9d 2108 . . . . 5 (¬ ∀𝑥 𝑥 = 𝑦 → (∃𝑦𝜑𝜑))
1110anim1d 587 . . . 4 (¬ ∀𝑥 𝑥 = 𝑦 → ((∃𝑦𝜑 ∧ ∃𝑦𝜓) → (𝜑 ∧ ∃𝑦𝜓)))
12 19.8a 2090 . . . 4 ((𝜑 ∧ ∃𝑦𝜓) → ∃𝑥(𝜑 ∧ ∃𝑦𝜓))
138, 11, 12syl56 36 . . 3 (¬ ∀𝑥 𝑥 = 𝑦 → (∃𝑦(𝜑𝜓) → ∃𝑥(𝜑 ∧ ∃𝑦𝜓)))
147, 13pm2.61i 176 . 2 (∃𝑦(𝜑𝜓) → ∃𝑥(𝜑 ∧ ∃𝑦𝜓))
151, 14exlimi 2124 1 (∃𝑥𝑦(𝜑𝜓) → ∃𝑥(𝜑 ∧ ∃𝑦𝜓))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 383  ∀wal 1521  ∃wex 1744  Ⅎwnf 1748 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-10 2059  ax-12 2087  ax-13 2282 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-ex 1745  df-nf 1750 This theorem is referenced by:  oprabid  6717
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