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Theorem excomimOLD 1858
Description: Obsolete proof of excomim 1742 as of 8-Jan-2018. (Contributed by NM, 5-Aug-1993.) (Revised by Mario Carneiro, 24-Sep-2016.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
excomimOLD (xyφyxφ)

Proof of Theorem excomimOLD
StepHypRef Expression
1 19.8a 1756 . . 3 (φxφ)
212eximi 1577 . 2 (xyφxyxφ)
3 nfe1 1732 . . . 4 xxφ
43nfex 1843 . . 3 xyxφ
5419.9 1783 . 2 (xyxφyxφ)
62, 5sylib 188 1 (xyφyxφ)
Colors of variables: wff setvar class
Syntax hints:  wi 4  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-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746
This theorem depends on definitions:  df-bi 177  df-ex 1542  df-nf 1545
This theorem is referenced by: (None)
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