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Theorem sb8 2169
Description: Substitution of variable in universal quantifier. (Contributed by NM, 16-May-1993.) (Revised by Mario Carneiro, 6-Oct-2016.) (Proof shortened by Jim Kingdon, 15-Jan-2018.)
Hypothesis
Ref Expression
sb5rf.1  |-  F/ y
ph
Assertion
Ref Expression
sb8  |-  ( A. x ph  <->  A. y [ y  /  x ] ph )

Proof of Theorem sb8
StepHypRef Expression
1 sb5rf.1 . 2  |-  F/ y
ph
21nfs1 2106 . 2  |-  F/ x [ y  /  x ] ph
3 sbequ12 1997 . 2  |-  ( x  =  y  ->  ( ph 
<->  [ y  /  x ] ph ) )
41, 2, 3cbval 2026 1  |-  ( A. x ph  <->  A. y [ y  /  x ] ph )
Colors of variables: wff setvar class
Syntax hints:    <-> wb 184   A.wal 1396   F/wnf 1621   [wsb 1744
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1623  ax-4 1636  ax-5 1709  ax-6 1752  ax-7 1795  ax-10 1842  ax-11 1847  ax-12 1859  ax-13 2004
This theorem depends on definitions:  df-bi 185  df-an 369  df-ex 1618  df-nf 1622  df-sb 1745
This theorem is referenced by:  sbhb  2184  sbnf2  2185  sb8eu  2319  sb8euOLD  2320  sb8iota  5541  mo5f  27584  wl-sb8eut  30265  sbcalf  30760  ax11-pm2  34829  bj-nfcf  34912
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