Theorem mobid 2080

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

Step	Hyp	Ref	Expression
1		mobid.1	. . . 4 |- F/ x ph
2		mobid.2	. . . 4 |- ( ph -> ( ps <-> ch ) )
3	1, 2	exbid 1630	. . 3 |- ( ph -> ( E. x ps <-> E. x ch ) )
4	1, 2	eubid 2052	. . 3 |- ( ph -> ( E! x ps <-> E! x ch ) )
5	3, 4	imbi12d 234	. 2 |- ( ph -> ( ( E. x ps -> E! x ps ) <-> ( E. x ch -> E! x ch ) ) )
6		df-mo 2049	. 2 |- ( E* x ps <-> ( E. x ps -> E! x ps ) )
7		df-mo 2049	. 2 |- ( E* x ch <-> ( E. x ch -> E! x ch ) )
8	5, 6, 7	3bitr4g 223	1 |- ( ph -> ( E* x ps <-> E* x ch ) )

Syntax hints:   -> wi 4   <-> wb 105   F/wnf 1474   E.wex 1506   E!weu 2045   E*wmo 2046

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 1461  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-4 1524  ax-17 1540  ax-ial 1548

This theorem depends on definitions:  df-bi 117  df-nf 1475  df-eu 2048  df-mo 2049

This theorem is referenced by:  mobidv  2081  rmobida  2684  rmoeq1f  2692