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Theorem mobid 2077
Description: Formula-building rule for "at most one" quantifier (deduction form). (Contributed by NM, 8-Mar-1995.)
Hypotheses
Ref Expression
mobid.1  |-  F/ x ph
mobid.2  |-  ( ph  ->  ( ps  <->  ch )
)
Assertion
Ref Expression
mobid  |-  ( ph  ->  ( E* x ps  <->  E* x ch ) )

Proof of Theorem mobid
StepHypRef Expression
1 mobid.1 . . . 4  |-  F/ x ph
2 mobid.2 . . . 4  |-  ( ph  ->  ( ps  <->  ch )
)
31, 2exbid 1627 . . 3  |-  ( ph  ->  ( E. x ps  <->  E. x ch ) )
41, 2eubid 2049 . . 3  |-  ( ph  ->  ( E! x ps  <->  E! x ch ) )
53, 4imbi12d 234 . 2  |-  ( ph  ->  ( ( E. x ps  ->  E! x ps )  <->  ( E. x ch  ->  E! x ch ) ) )
6 df-mo 2046 . 2  |-  ( E* x ps  <->  ( E. x ps  ->  E! x ps ) )
7 df-mo 2046 . 2  |-  ( E* x ch  <->  ( E. x ch  ->  E! x ch ) )
85, 6, 73bitr4g 223 1  |-  ( ph  ->  ( E* x ps  <->  E* x ch ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 105   F/wnf 1471   E.wex 1503   E!weu 2042   E*wmo 2043
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1458  ax-gen 1460  ax-ie1 1504  ax-ie2 1505  ax-4 1521  ax-17 1537  ax-ial 1545
This theorem depends on definitions:  df-bi 117  df-nf 1472  df-eu 2045  df-mo 2046
This theorem is referenced by:  mobidv  2078  rmobida  2681  rmoeq1f  2689
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