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Theorem 2moexv 2711
 Description: Double quantification with "at most one". (Contributed by NM, 3-Dec-2001.)
Assertion
Ref Expression
2moexv (∃*𝑥𝑦𝜑 → ∀𝑦∃*𝑥𝜑)
Distinct variable group:   𝑥,𝑦
Allowed substitution hints:   𝜑(𝑥,𝑦)

Proof of Theorem 2moexv
StepHypRef Expression
1 nfe1 2147 . . 3 𝑦𝑦𝜑
21nfmov 2642 . 2 𝑦∃*𝑥𝑦𝜑
3 19.8a 2172 . . 3 (𝜑 → ∃𝑦𝜑)
43moimi 2625 . 2 (∃*𝑥𝑦𝜑 → ∃*𝑥𝜑)
52, 4alrimi 2206 1 (∃*𝑥𝑦𝜑 → ∀𝑦∃*𝑥𝜑)
 Colors of variables: wff setvar class Syntax hints:   → wi 4  ∀wal 1528  ∃wex 1773  ∃*wmo 2618 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1904  ax-6 1963  ax-7 2008  ax-10 2138  ax-11 2153  ax-12 2169 This theorem depends on definitions:  df-bi 208  df-or 844  df-tru 1533  df-ex 1774  df-nf 1778  df-mo 2620 This theorem is referenced by:  2eu5  2741
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