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Theorem equs5eOLD 1911
Description: Obsolete proof of equs5e 1910 as of 15-Jan-2018. (Contributed by NM, 2-Feb-2007.) (New usage is discouraged.) (Proof modification is discouraged.)
Assertion
Ref Expression
equs5eOLD  |-  ( E. x ( x  =  y  /\  ph )  ->  A. x ( x  =  y  ->  E. y ph ) )

Proof of Theorem equs5eOLD
StepHypRef Expression
1 nfe1 1747 . 2  |-  F/ x E. x ( x  =  y  /\  ph )
2 equs3 1654 . . 3  |-  ( E. x ( x  =  y  /\  ph )  <->  -. 
A. x ( x  =  y  ->  -.  ph ) )
3 ax-11 1761 . . . . 5  |-  ( x  =  y  ->  ( A. y  -.  ph  ->  A. x ( x  =  y  ->  -.  ph )
) )
43con3rr3 130 . . . 4  |-  ( -. 
A. x ( x  =  y  ->  -.  ph )  ->  ( x  =  y  ->  -.  A. y  -.  ph ) )
5 df-ex 1551 . . . 4  |-  ( E. y ph  <->  -.  A. y  -.  ph )
64, 5syl6ibr 219 . . 3  |-  ( -. 
A. x ( x  =  y  ->  -.  ph )  ->  ( x  =  y  ->  E. y ph ) )
72, 6sylbi 188 . 2  |-  ( E. x ( x  =  y  /\  ph )  ->  ( x  =  y  ->  E. y ph )
)
81, 7alrimi 1781 1  |-  ( E. x ( x  =  y  /\  ph )  ->  A. x ( x  =  y  ->  E. y ph ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    /\ wa 359   A.wal 1549   E.wex 1550
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1555  ax-5 1566  ax-17 1626  ax-9 1666  ax-8 1687  ax-6 1744  ax-11 1761
This theorem depends on definitions:  df-bi 178  df-an 361  df-ex 1551  df-nf 1554
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