Theorem mopick 2097

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 1519	. . . 4 |- ( ( ph /\ ps ) -> A. y ( ph /\ ps ) )
2		hbs1 1931	. . . . 5 |- ( [ y / x ] ph -> A. x [ y / x ] ph )
3		hbs1 1931	. . . . 5 |- ( [ y / x ] ps -> A. x [ y / x ] ps )
4	2, 3	hban 1540	. . . 4 |- ( ( [ y / x ] ph /\ [ y / x ] ps ) -> A. x ( [ y / x ] ph /\ [ y / x ] ps ) )
5		sbequ12 1764	. . . . 5 |- ( x = y -> ( ph <-> [ y / x ] ph ) )
6		sbequ12 1764	. . . . 5 |- ( x = y -> ( ps <-> [ y / x ] ps ) )
7	5, 6	anbi12d 470	. . . 4 |- ( x = y -> ( ( ph /\ ps ) <-> ( [ y / x ] ph /\ [ y / x ] ps ) ) )
8	1, 4, 7	cbvexh 1748	. . 3 |- ( E. x ( ph /\ ps ) <-> E. y ( [ y / x ] ph /\ [ y / x ] ps ) )
9		ax-17 1519	. . . . . . 7 |- ( ph -> A. y ph )
10	9	mo3h 2072	. . . . . 6 |- ( E* x ph <-> A. x A. y ( ( ph /\ [ y / x ] ph ) -> x = y ) )
11		ax-4 1503	. . . . . . 7 |- ( A. y ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ( ph /\ [ y / x ] ph ) -> x = y ) )
12	11	sps 1530	. . . . . 6 |- ( A. x A. y ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ( ph /\ [ y / x ] ph ) -> x = y ) )
13	10, 12	sylbi 120	. . . . 5 |- ( E* x ph -> ( ( ph /\ [ y / x ] ph ) -> x = y ) )
14		sbequ2 1762	. . . . . . . . 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 256	. . . . . . 7 |- ( ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ph -> ( [ y / x ] ph -> ( [ y / x ] ps -> ps ) ) ) )
17	16	com4t 85	. . . . . 6 |- ( [ y / x ] ph -> ( [ y / x ] ps -> ( ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ph -> ps ) ) ) )
18	17	imp 123	. . . . 5 |- ( ( [ y / x ] ph /\ [ y / x ] ps ) -> ( ( ( ph /\ [ y / x ] ph ) -> x = y ) -> ( ph -> ps ) ) )
19	13, 18	syl5 32	. . . 4 |- ( ( [ y / x ] ph /\ [ y / x ] ps ) -> ( E* x ph -> ( ph -> ps ) ) )
20	19	exlimiv 1591	. . 3 |- ( E. y ( [ y / x ] ph /\ [ y / x ] ps ) -> ( E* x ph -> ( ph -> ps ) ) )
21	8, 20	sylbi 120	. 2 |- ( E. x ( ph /\ ps ) -> ( E* x ph -> ( ph -> ps ) ) )
22	21	impcom 124	1 |- ( ( E* x ph /\ E. x ( ph /\ ps ) ) -> ( ph -> ps ) )

Syntax hints:   -> wi 4   /\ wa 103   A.wal 1346   E.wex 1485   [wsb 1755   E*wmo 2020

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 704  ax-5 1440  ax-7 1441  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-10 1498  ax-11 1499  ax-i12 1500  ax-bndl 1502  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-i5r 1528

This theorem depends on definitions:  df-bi 116  df-nf 1454  df-sb 1756  df-eu 2022  df-mo 2023

This theorem is referenced by:  eupick  2098  mopick2  2102  moexexdc  2103  euexex  2104  morex  2914  imadif  5278  funimaexglem  5281