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Theorem sbequ5 1792
Description: Substitution does not change an identical variable specifier. (Contributed by NM, 5-Aug-1993.) (Revised by NM, 21-Dec-2004.)
Assertion
Ref Expression
sbequ5  |-  ( [ w  /  z ] A. x  x  =  y  <->  A. x  x  =  y )

Proof of Theorem sbequ5
StepHypRef Expression
1 nfae 1729 . 2  |-  F/ z A. x  x  =  y
21sbf 1787 1  |-  ( [ w  /  z ] A. x  x  =  y  <->  A. x  x  =  y )
Colors of variables: wff set class
Syntax hints:    <-> wb 105   A.wal 1361   [wsb 1772
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1457  ax-7 1458  ax-gen 1459  ax-ie1 1503  ax-ie2 1504  ax-8 1514  ax-10 1515  ax-11 1516  ax-i12 1517  ax-4 1520  ax-17 1536  ax-i9 1540  ax-ial 1544
This theorem depends on definitions:  df-bi 117  df-nf 1471  df-sb 1773
This theorem is referenced by: (None)
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