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Theorem rexcomf 2639
Description: Commutation of restricted quantifiers. (Contributed by Mario Carneiro, 14-Oct-2016.)
Hypotheses
Ref Expression
ralcomf.1  |-  F/_ y A
ralcomf.2  |-  F/_ x B
Assertion
Ref Expression
rexcomf  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. y  e.  B  E. x  e.  A  ph )
Distinct variable group:    x, y
Allowed substitution hints:    ph( x, y)    A( x, y)    B( x, y)

Proof of Theorem rexcomf
StepHypRef Expression
1 ancom 266 . . . . 5  |-  ( ( x  e.  A  /\  y  e.  B )  <->  ( y  e.  B  /\  x  e.  A )
)
21anbi1i 458 . . . 4  |-  ( ( ( x  e.  A  /\  y  e.  B
)  /\  ph )  <->  ( (
y  e.  B  /\  x  e.  A )  /\  ph ) )
322exbii 1606 . . 3  |-  ( E. x E. y ( ( x  e.  A  /\  y  e.  B
)  /\  ph )  <->  E. x E. y ( ( y  e.  B  /\  x  e.  A )  /\  ph ) )
4 excom 1664 . . 3  |-  ( E. x E. y ( ( y  e.  B  /\  x  e.  A
)  /\  ph )  <->  E. y E. x ( ( y  e.  B  /\  x  e.  A )  /\  ph ) )
53, 4bitri 184 . 2  |-  ( E. x E. y ( ( x  e.  A  /\  y  e.  B
)  /\  ph )  <->  E. y E. x ( ( y  e.  B  /\  x  e.  A )  /\  ph ) )
6 ralcomf.1 . . 3  |-  F/_ y A
76r2exf 2495 . 2  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. x E. y ( ( x  e.  A  /\  y  e.  B )  /\  ph ) )
8 ralcomf.2 . . 3  |-  F/_ x B
98r2exf 2495 . 2  |-  ( E. y  e.  B  E. x  e.  A  ph  <->  E. y E. x ( ( y  e.  B  /\  x  e.  A )  /\  ph ) )
105, 7, 93bitr4i 212 1  |-  ( E. x  e.  A  E. y  e.  B  ph  <->  E. y  e.  B  E. x  e.  A  ph )
Colors of variables: wff set class
Syntax hints:    /\ wa 104    <-> wb 105   E.wex 1492    e. wcel 2148   F/_wnfc 2306   E.wrex 2456
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 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-ext 2159
This theorem depends on definitions:  df-bi 117  df-nf 1461  df-sb 1763  df-cleq 2170  df-clel 2173  df-nfc 2308  df-rex 2461
This theorem is referenced by:  rexcom  2641
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