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Theorem 19.21bbi 1865
Description: Inference removing double quantifier. (Contributed by NM, 20-Apr-1994.)
Hypothesis
Ref Expression
19.21bbi.1 (φxyψ)
Assertion
Ref Expression
19.21bbi (φψ)

Proof of Theorem 19.21bbi
StepHypRef Expression
1 19.21bbi.1 . . 3 (φxyψ)
2119.21bi 1758 . 2 (φyψ)
3219.21bi 1758 1 (φψ)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wal 1540
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-11 1746
This theorem depends on definitions:  df-bi 177  df-ex 1542
This theorem is referenced by:  ssfin  4470  funun  5146  fnfrec  6320
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