Users' Mathboxes Mathbox for Thierry Arnoux < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >   Mathboxes  >  mo5f Unicode version

Theorem mo5f 23818
Description: Alternate definition of "at most one." (Contributed by Thierry Arnoux, 1-Mar-2017.)
Hypotheses
Ref Expression
mo5f.1  |-  F/ i
ph
mo5f.2  |-  F/ j
ph
Assertion
Ref Expression
mo5f  |-  ( E* x ph  <->  A. i A. j ( ( [ i  /  x ] ph  /\  [ j  /  x ] ph )  -> 
i  =  j ) )
Distinct variable group:    i, j, x
Allowed substitution hints:    ph( x, i, j)

Proof of Theorem mo5f
StepHypRef Expression
1 mo5f.2 . . 3  |-  F/ j
ph
21mo3 2271 . 2  |-  ( E* x ph  <->  A. x A. j ( ( ph  /\ 
[ j  /  x ] ph )  ->  x  =  j ) )
3 mo5f.1 . . . . . 6  |-  F/ i
ph
43nfsb 2144 . . . . . 6  |-  F/ i [ j  /  x ] ph
53, 4nfan 1836 . . . . 5  |-  F/ i ( ph  /\  [
j  /  x ] ph )
6 nfv 1626 . . . . 5  |-  F/ i  x  =  j
75, 6nfim 1822 . . . 4  |-  F/ i ( ( ph  /\  [ j  /  x ] ph )  ->  x  =  j )
87nfal 1854 . . 3  |-  F/ i A. j ( (
ph  /\  [ j  /  x ] ph )  ->  x  =  j )
98sb8 2127 . 2  |-  ( A. x A. j ( (
ph  /\  [ j  /  x ] ph )  ->  x  =  j )  <->  A. i [ i  /  x ] A. j ( ( ph  /\  [
j  /  x ] ph )  ->  x  =  j ) )
10 sbim 2100 . . . . 5  |-  ( [ i  /  x ]
( ( ph  /\  [ j  /  x ] ph )  ->  x  =  j )  <->  ( [
i  /  x ]
( ph  /\  [ j  /  x ] ph )  ->  [ i  /  x ] x  =  j ) )
11 sban 2104 . . . . . . 7  |-  ( [ i  /  x ]
( ph  /\  [ j  /  x ] ph ) 
<->  ( [ i  /  x ] ph  /\  [
i  /  x ] [ j  /  x ] ph ) )
12 nfs1v 2141 . . . . . . . . . 10  |-  F/ x [ j  /  x ] ph
1312sbf 2061 . . . . . . . . 9  |-  ( [ i  /  x ] [ j  /  x ] ph  <->  [ j  /  x ] ph )
1413bicomi 194 . . . . . . . 8  |-  ( [ j  /  x ] ph 
<->  [ i  /  x ] [ j  /  x ] ph )
1514anbi2i 676 . . . . . . 7  |-  ( ( [ i  /  x ] ph  /\  [ j  /  x ] ph ) 
<->  ( [ i  /  x ] ph  /\  [
i  /  x ] [ j  /  x ] ph ) )
1611, 15bitr4i 244 . . . . . 6  |-  ( [ i  /  x ]
( ph  /\  [ j  /  x ] ph ) 
<->  ( [ i  /  x ] ph  /\  [
j  /  x ] ph ) )
17 equsb3 2137 . . . . . 6  |-  ( [ i  /  x ]
x  =  j  <->  i  =  j )
1816, 17imbi12i 317 . . . . 5  |-  ( ( [ i  /  x ] ( ph  /\  [ j  /  x ] ph )  ->  [ i  /  x ] x  =  j )  <->  ( ( [ i  /  x ] ph  /\  [ j  /  x ] ph )  ->  i  =  j ) )
1910, 18bitri 241 . . . 4  |-  ( [ i  /  x ]
( ( ph  /\  [ j  /  x ] ph )  ->  x  =  j )  <->  ( ( [ i  /  x ] ph  /\  [ j  /  x ] ph )  ->  i  =  j ) )
2019sbalv 2165 . . 3  |-  ( [ i  /  x ] A. j ( ( ph  /\ 
[ j  /  x ] ph )  ->  x  =  j )  <->  A. j
( ( [ i  /  x ] ph  /\ 
[ j  /  x ] ph )  ->  i  =  j ) )
2120albii 1572 . 2  |-  ( A. i [ i  /  x ] A. j ( (
ph  /\  [ j  /  x ] ph )  ->  x  =  j )  <->  A. i A. j ( ( [ i  /  x ] ph  /\  [
j  /  x ] ph )  ->  i  =  j ) )
222, 9, 213bitri 263 1  |-  ( E* x ph  <->  A. i A. j ( ( [ i  /  x ] ph  /\  [ j  /  x ] ph )  -> 
i  =  j ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 177    /\ wa 359   A.wal 1546   F/wnf 1550   [wsb 1655   E*wmo 2241
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1552  ax-5 1563  ax-17 1623  ax-9 1661  ax-8 1682  ax-6 1736  ax-7 1741  ax-11 1753  ax-12 1939
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-tru 1325  df-ex 1548  df-nf 1551  df-sb 1656  df-eu 2244  df-mo 2245
  Copyright terms: Public domain W3C validator