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Theorem exmo 2249
Description: Something exists or at most one exists. (Contributed by NM, 8-Mar-1995.)
Assertion
Ref Expression
exmo (xφ ∃*xφ)

Proof of Theorem exmo
StepHypRef Expression
1 pm2.21 100 . . 3 xφ → (xφ∃!xφ))
2 df-mo 2209 . . 3 (∃*xφ ↔ (xφ∃!xφ))
31, 2sylibr 203 . 2 xφ∃*xφ)
43orri 365 1 (xφ ∃*xφ)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4   wo 357  wex 1541  ∃!weu 2204  ∃*wmo 2205
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 177  df-or 359  df-mo 2209
This theorem is referenced by:  moexex  2273  mo2icl  3015  mosubopt  4612
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