Theorem mopick 1978

Description: "At most one" picks a variable value, eliminating an existential quantifier. (Contributed by NM, 27-Jan-1997.)

Assertion

Ref	Expression
mopick	|- ( ( E* x ph /\ E. x ( ph /\ ps ) ) -> ( ph -> ps ) )

Proof of Theorem mopick

Dummy variable y is distinct from all other variables.

Step	Hyp	Ref	Expression
1		ax-17 1419	. . . 4 |- ( ( ph /\ ps ) -> A. y ( ph /\ ps ) )
2		hbs1 1814	. . . . 5 |- ( [ y / x ] ph -> A. x [ y / x ] ph )
3		hbs1 1814	. . . . 5 |- ( [ y / x ] ps -> A. x [ y / x ] ps )
4	2, 3	hban 1439	. . . 4 |- ( ( [ y / x ] ph /\ [ y / x ] ps ) -> A. x ( [ y / x ] ph /\ [ y / x ] ps ) )
5		sbequ12 1654	. . . . 5 |- ( x = y -> ( ph <-> [ y / x ] ph ) )
6		sbequ12 1654	. . . . 5 |- ( x = y -> ( ps <-> [ y / x ] ps ) )
7	5, 6	anbi12d 442	. . . 4 |- ( x = y -> ( ( ph /\ ps ) <-> ( [ y / x ] ph /\ [ y / x ] ps ) ) )
8	1, 4, 7	cbvexh 1638	. . 3 |- ( E. x ( ph /\ ps ) <-> E. y ( [ y / x ] ph /\ [ y / x ] ps ) )
9		ax-17 1419	. . . . . . 7 |- ( ph -> A. y ph )
10	9	mo3h 1953	. . . . . 6 |- ( E* x ph <-> A. x A. y ( ( ph /\ [ y / x ] ph ) -> x = y ) )
11		ax-4 1400	. . . . . . 7 |- ( A. y ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ( ph /\ [ y / x ] ph ) -> x = y ) )
12	11	sps 1430	. . . . . 6 |- ( A. x A. y ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ( ph /\ [ y / x ] ph ) -> x = y ) )
13	10, 12	sylbi 114	. . . . 5 |- ( E* x ph -> ( ( ph /\ [ y / x ] ph ) -> x = y ) )
14		sbequ2 1652	. . . . . . . . 9 |- ( x = y -> ( [ y / x ] ps -> ps ) )
15	14	imim2i 12	. . . . . . . 8 |- ( ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ( ph /\ [ y / x ] ph ) -> ( [ y / x ] ps -> ps ) ) )
16	15	expd 245	. . . . . . 7 |- ( ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ph -> ( [ y / x ] ph -> ( [ y / x ] ps -> ps ) ) ) )
17	16	com4t 79	. . . . . 6 |- ( [ y / x ] ph -> ( [ y / x ] ps -> ( ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ph -> ps ) ) ) )
18	17	imp 115	. . . . 5 |- ( ( [ y / x ] ph /\ [ y / x ] ps ) -> ( ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ph -> ps ) ) )
19	13, 18	syl5 28	. . . 4 |- ( ( [ y / x ] ph /\ [ y / x ] ps ) -> ( E* x ph -> ( ph -> ps ) ) )
20	19	exlimiv 1489	. . 3 |- ( E. y ( [ y / x ] ph /\ [ y / x ] ps ) -> ( E* x ph -> ( ph -> ps ) ) )
21	8, 20	sylbi 114	. 2 |- ( E. x ( ph /\ ps ) -> ( E* x ph -> ( ph -> ps ) ) )
22	21	impcom 116	1 |- ( ( E* x ph /\ E. x ( ph /\ ps ) ) -> ( ph -> ps ) )

Syntax hints:   -> wi 4   /\ wa 97   A.wal 1241   E.wex 1381   [wsb 1645   E*wmo 1901

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428

This theorem depends on definitions:  df-bi 110  df-nf 1350  df-sb 1646  df-eu 1903  df-mo 1904

This theorem is referenced by:  eupick  1979  mopick2  1983  moexexdc  1984  euexex  1985  morex  2725  imadif  4979  funimaexglem  4982