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Theorem 19.43OLD 1617
 Description: Obsolete proof of 19.43 1616 as of 3-May-2017. Leave this in for the example on the mmrecent.html page. (Contributed by NM, 5-Aug-1993.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
19.43OLD

Proof of Theorem 19.43OLD
StepHypRef Expression
1 ioran 478 . . . . 5
21albii 1576 . . . 4
3 19.26 1604 . . . 4
4 alnex 1553 . . . . 5
5 alnex 1553 . . . . 5
64, 5anbi12i 680 . . . 4
72, 3, 63bitri 264 . . 3
87notbii 289 . 2
9 df-ex 1552 . 2
10 oran 484 . 2
118, 9, 103bitr4i 270 1
 Colors of variables: wff set class Syntax hints:   wn 3   wb 178   wo 359   wa 360  wal 1550  wex 1551 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1556  ax-5 1567 This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-ex 1552
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