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Theorem r19.45av 2515
Description: Restricted version of one direction of Theorem 19.45 of [Margaris] p. 90. (The other direction doesn't hold when 𝐴 is empty.) (Contributed by NM, 2-Apr-2004.)
Assertion
Ref Expression
r19.45av (∃𝑥𝐴 (𝜑𝜓) → (𝜑 ∨ ∃𝑥𝐴 𝜓))
Distinct variable group:   𝜑,𝑥
Allowed substitution hints:   𝜓(𝑥)   𝐴(𝑥)

Proof of Theorem r19.45av
StepHypRef Expression
1 r19.43 2513 . 2 (∃𝑥𝐴 (𝜑𝜓) ↔ (∃𝑥𝐴 𝜑 ∨ ∃𝑥𝐴 𝜓))
2 idd 21 . . . 4 (𝑥𝐴 → (𝜑𝜑))
32rexlimiv 2472 . . 3 (∃𝑥𝐴 𝜑𝜑)
43orim1i 710 . 2 ((∃𝑥𝐴 𝜑 ∨ ∃𝑥𝐴 𝜓) → (𝜑 ∨ ∃𝑥𝐴 𝜓))
51, 4sylbi 119 1 (∃𝑥𝐴 (𝜑𝜓) → (𝜑 ∨ ∃𝑥𝐴 𝜓))
Colors of variables: wff set class
Syntax hints:  wi 4  wo 662  wcel 1434  wrex 2350
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-io 663  ax-5 1377  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-4 1441  ax-17 1460  ax-ial 1468  ax-i5r 1469
This theorem depends on definitions:  df-bi 115  df-nf 1391  df-ral 2354  df-rex 2355
This theorem is referenced by: (None)
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