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Theorem hba1OLD 1787
Description: Obsolete proof of hba1 1786 as of 15-Dec-2017 (Contributed by NM, 5-Aug-1993.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
hba1OLD (xφxxφ)

Proof of Theorem hba1OLD
StepHypRef Expression
1 sp 1747 . . 3 (x ¬ xφ → ¬ xφ)
21con2i 112 . 2 (xφ → ¬ x ¬ xφ)
3 hbn1 1730 . 2 x ¬ xφx ¬ x ¬ xφ)
4 hbn1 1730 . . . 4 xφx ¬ xφ)
54con1i 121 . . 3 x ¬ xφxφ)
65alimi 1559 . 2 (x ¬ x ¬ xφxxφ)
72, 3, 63syl 18 1 (xφxxφ)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wal 1540
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-11 1746
This theorem depends on definitions:  df-bi 177  df-ex 1542
This theorem is referenced by: (None)
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