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Theorem ralcom3 2942
Description: A commutation law for restricted universal quantifiers that swaps the domains of the restriction. (Contributed by NM, 22-Feb-2004.)
Assertion
Ref Expression
ralcom3  |-  ( A. x  e.  A  (
x  e.  B  ->  ph )  <->  A. x  e.  B  ( x  e.  A  ->  ph ) )

Proof of Theorem ralcom3
StepHypRef Expression
1 pm2.04 84 . . 3  |-  ( ( x  e.  A  -> 
( x  e.  B  ->  ph ) )  -> 
( x  e.  B  ->  ( x  e.  A  ->  ph ) ) )
21ralimi2 2793 . 2  |-  ( A. x  e.  A  (
x  e.  B  ->  ph )  ->  A. x  e.  B  ( x  e.  A  ->  ph )
)
3 pm2.04 84 . . 3  |-  ( ( x  e.  B  -> 
( x  e.  A  ->  ph ) )  -> 
( x  e.  A  ->  ( x  e.  B  ->  ph ) ) )
43ralimi2 2793 . 2  |-  ( A. x  e.  B  (
x  e.  A  ->  ph )  ->  A. x  e.  A  ( x  e.  B  ->  ph )
)
52, 4impbii 192 1  |-  ( A. x  e.  A  (
x  e.  B  ->  ph )  <->  A. x  e.  B  ( x  e.  A  ->  ph ) )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    <-> wb 189    e. wcel 1904   A.wral 2756
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1677  ax-4 1690
This theorem depends on definitions:  df-bi 190  df-ral 2761
This theorem is referenced by:  tgss2  20080  ist1-3  20442  isreg2  20470
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