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Theorem 19.43OLD 1606
Description: Obsolete proof of 19.43 1605 as of 3-May-2016. 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 476 . . . . 5
21albii 1566 . . . 4
3 19.26 1593 . . . 4
4 alnex 1543 . . . . 5
5 alnex 1543 . . . . 5
64, 5anbi12i 678 . . . 4
72, 3, 63bitri 262 . . 3
87notbii 287 . 2
9 df-ex 1542 . 2
10 oran 482 . 2
118, 9, 103bitr4i 268 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   wb 176   wo 357   wa 358  wal 1540  wex 1541
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-ex 1542
This theorem is referenced by: (None)
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