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Theorem retbwax4 1480
Description: tbw-ax4 1468 rederived from merco1 1478. (Contributed by Anthony Hart, 17-Sep-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
retbwax4 ( ⊥ → φ)

Proof of Theorem retbwax4
StepHypRef Expression
1 merco1lem1 1479 . 2 (φ → ( ⊥ → φ))
2 merco1lem1 1479 . 2 ((φ → ( ⊥ → φ)) → ( ⊥ → φ))
31, 2ax-mp 5 1 ( ⊥ → φ)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wfal 1317
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 177  df-tru 1319  df-fal 1320
This theorem is referenced by: (None)
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