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Theorem subsym1 31092
Description: A symmetry with  [ x  /  y ].

See negsym1 31082 for more information. (Contributed by Anthony Hart, 11-Sep-2011.)

Assertion
Ref Expression
subsym1  |-  ( [ x  /  y ] [ x  /  y ] F.  ->  [ x  /  y ] ph )

Proof of Theorem subsym1
StepHypRef Expression
1 fal 1444 . . . . . . . . . 10  |-  -. F.
21intnan 922 . . . . . . . . 9  |-  -.  (
y  =  x  /\ F.  )
32nex 1672 . . . . . . . 8  |-  -.  E. y ( y  =  x  /\ F.  )
43intnan 922 . . . . . . 7  |-  -.  (
( y  =  x  -> F.  )  /\  E. y ( y  =  x  /\ F.  )
)
5 df-sb 1791 . . . . . . 7  |-  ( [ x  /  y ] F.  <->  ( ( y  =  x  -> F.  )  /\  E. y ( y  =  x  /\ F.  ) ) )
64, 5mtbir 300 . . . . . 6  |-  -.  [
x  /  y ] F.
76intnan 922 . . . . 5  |-  -.  (
y  =  x  /\  [ x  /  y ] F.  )
87nex 1672 . . . 4  |-  -.  E. y ( y  =  x  /\  [ x  /  y ] F.  )
98intnan 922 . . 3  |-  -.  (
( y  =  x  ->  [ x  / 
y ] F.  )  /\  E. y ( y  =  x  /\  [
x  /  y ] F.  ) )
10 df-sb 1791 . . 3  |-  ( [ x  /  y ] [ x  /  y ] F.  <->  ( ( y  =  x  ->  [ x  /  y ] F.  )  /\  E. y ( y  =  x  /\  [ x  /  y ] F.  ) ) )
119, 10mtbir 300 . 2  |-  -.  [
x  /  y ] [ x  /  y ] F.
1211pm2.21i 134 1  |-  ( [ x  /  y ] [ x  /  y ] F.  ->  [ x  /  y ] ph )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    /\ wa 370   F. wfal 1442   E.wex 1657   [wsb 1790
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1663
This theorem depends on definitions:  df-bi 188  df-an 372  df-tru 1440  df-fal 1443  df-ex 1658  df-sb 1791
This theorem is referenced by: (None)
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