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Theorem hbex 1946
Description: If is not free in , it is not free in . (Contributed by NM, 12-Mar-1993.)
Hypothesis
Ref Expression
hbex.1
Assertion
Ref Expression
hbex

Proof of Theorem hbex
StepHypRef Expression
1 df-ex 1613 . 2
2 hbex.1 . . . . 5
32hbn 1895 . . . 4
43hbal 1844 . . 3
54hbn 1895 . 2
61, 5hbxfrbi 1643 1
Colors of variables: wff setvar class
Syntax hints:  -.wn 3  ->wi 4  A.wal 1393  E.wex 1612
This theorem is referenced by:  nfex  1948
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1618  ax-4 1631  ax-5 1704  ax-6 1747  ax-7 1790  ax-10 1837  ax-11 1842  ax-12 1854
This theorem depends on definitions:  df-bi 185  df-ex 1613
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