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Theorem dveeq2 1803
Description: Quantifier introduction when one pair of variables is distinct. (Contributed by NM, 2-Jan-2002.)
Assertion
Ref Expression
dveeq2  |-  ( -. 
A. x  x  =  y  ->  ( z  =  y  ->  A. x  z  =  y )
)
Distinct variable group:    x, z

Proof of Theorem dveeq2
StepHypRef Expression
1 ax12or 1496 . . . . 5  |-  ( A. x  x  =  z  \/  ( A. x  x  =  y  \/  A. x ( z  =  y  ->  A. x  z  =  y )
) )
2 orcom 718 . . . . . 6  |-  ( ( A. x  x  =  y  \/  A. x
( z  =  y  ->  A. x  z  =  y ) )  <->  ( A. x ( z  =  y  ->  A. x  z  =  y )  \/  A. x  x  =  y ) )
32orbi2i 752 . . . . 5  |-  ( ( A. x  x  =  z  \/  ( A. x  x  =  y  \/  A. x ( z  =  y  ->  A. x  z  =  y )
) )  <->  ( A. x  x  =  z  \/  ( A. x ( z  =  y  ->  A. x  z  =  y )  \/  A. x  x  =  y
) ) )
41, 3mpbi 144 . . . 4  |-  ( A. x  x  =  z  \/  ( A. x ( z  =  y  ->  A. x  z  =  y )  \/  A. x  x  =  y
) )
5 orass 757 . . . 4  |-  ( ( ( A. x  x  =  z  \/  A. x ( z  =  y  ->  A. x  z  =  y )
)  \/  A. x  x  =  y )  <->  ( A. x  x  =  z  \/  ( A. x ( z  =  y  ->  A. x  z  =  y )  \/  A. x  x  =  y ) ) )
64, 5mpbir 145 . . 3  |-  ( ( A. x  x  =  z  \/  A. x
( z  =  y  ->  A. x  z  =  y ) )  \/ 
A. x  x  =  y )
7 orel2 716 . . 3  |-  ( -. 
A. x  x  =  y  ->  ( (
( A. x  x  =  z  \/  A. x ( z  =  y  ->  A. x  z  =  y )
)  \/  A. x  x  =  y )  ->  ( A. x  x  =  z  \/  A. x ( z  =  y  ->  A. x  z  =  y )
) ) )
86, 7mpi 15 . 2  |-  ( -. 
A. x  x  =  y  ->  ( A. x  x  =  z  \/  A. x ( z  =  y  ->  A. x  z  =  y )
) )
9 ax16 1801 . . 3  |-  ( A. x  x  =  z  ->  ( z  =  y  ->  A. x  z  =  y ) )
10 sp 1499 . . 3  |-  ( A. x ( z  =  y  ->  A. x  z  =  y )  ->  ( z  =  y  ->  A. x  z  =  y ) )
119, 10jaoi 706 . 2  |-  ( ( A. x  x  =  z  \/  A. x
( z  =  y  ->  A. x  z  =  y ) )  -> 
( z  =  y  ->  A. x  z  =  y ) )
128, 11syl 14 1  |-  ( -. 
A. x  x  =  y  ->  ( z  =  y  ->  A. x  z  =  y )
)
Colors of variables: wff set class
Syntax hints:   -. wn 3    -> wi 4    \/ wo 698   A.wal 1341
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-in2 605  ax-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522
This theorem depends on definitions:  df-bi 116  df-nf 1449  df-sb 1751
This theorem is referenced by:  nd5  1806  ax11v2  1808  dveeq1  2007
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