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Theorem excomOLD 1859
Description: Obsolete proof of excom 1741 as of 8-Jan-2018. (Contributed by NM, 5-Aug-1993.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
excomOLD (xyφyxφ)

Proof of Theorem excomOLD
StepHypRef Expression
1 excomim 1742 . 2 (xyφyxφ)
2 excomim 1742 . 2 (yxφxyφ)
31, 2impbii 180 1 (xyφyxφ)
Colors of variables: wff setvar class
Syntax hints:  wb 176  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  ax-7 1734
This theorem depends on definitions:  df-bi 177  df-ex 1542
This theorem is referenced by: (None)
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