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Theorem dedlem0a 918
Description: Lemma for an alternate version of weak deduction theorem. (Contributed by NM, 2-Apr-1994.) (Proof shortened by Andrew Salmon, 7-May-2011.) (Proof shortened by Wolf Lammen, 4-Dec-2012.)
Assertion
Ref Expression
dedlem0a

Proof of Theorem dedlem0a
StepHypRef Expression
1 iba 489 . 2
2 ax-1 5 . . 3
3 biimt 325 . . 3
42, 3syl 15 . 2
51, 4bitrd 244 1
Colors of variables: wff set class
Syntax hints:   wi 4   wb 176   wa 358
This theorem is referenced by:  iftrue  3668
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8
This theorem depends on definitions:  df-bi 177  df-an 360
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