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Theorem 19.25 1603
Description: Theorem 19.25 of [Margaris] p. 90. (Contributed by NM, 5-Aug-1993.)
Assertion
Ref Expression
19.25 (yx(φψ) → (yxφyxψ))

Proof of Theorem 19.25
StepHypRef Expression
1 19.35 1600 . . . 4 (x(φψ) ↔ (xφxψ))
21biimpi 186 . . 3 (x(φψ) → (xφxψ))
32alimi 1559 . 2 (yx(φψ) → y(xφxψ))
4 exim 1575 . 2 (y(xφxψ) → (yxφyxψ))
53, 4syl 15 1 (yx(φψ) → (yxφyxψ))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wal 1540  wex 1541
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557
This theorem depends on definitions:  df-bi 177  df-an 360  df-ex 1542
This theorem is referenced by: (None)
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