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Theorem falxortruOLD 1504
Description: Obsolete proof of falxortru 1503 as of 10-Jul-2020. (Contributed by David A. Wheeler, 9-May-2015.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
falxortruOLD  |-  ( ( F.  \/_ T.  )  <-> T.  )

Proof of Theorem falxortruOLD
StepHypRef Expression
1 df-xor 1416 . 2  |-  ( ( F.  \/_ T.  )  <->  -.  ( F.  <-> T.  )
)
2 falbitru 1491 . . 3  |-  ( ( F.  <-> T.  )  <-> F.  )
32notbii 302 . 2  |-  ( -.  ( F.  <-> T.  )  <->  -. F.  )
4 notfal 1489 . 2  |-  ( -. F.  <-> T.  )
51, 3, 43bitri 279 1  |-  ( ( F.  \/_ T.  )  <-> T.  )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    <-> wb 189    \/_ wxo 1415   T. wtru 1455   F. wfal 1459
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 190  df-xor 1416  df-tru 1457  df-fal 1460
This theorem is referenced by: (None)
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