NFE Home New Foundations Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  NFE Home  >  Th. List  >  biorf Unicode version

Theorem biorf 394
Description: A wff is equivalent to its disjunction with falsehood. Theorem *4.74 of [WhiteheadRussell] p. 121. (Contributed by NM, 23-Mar-1995.) (Proof shortened by Wolf Lammen, 18-Nov-2012.)
Assertion
Ref Expression
biorf

Proof of Theorem biorf
StepHypRef Expression
1 olc 373 . 2
2 orel1 371 . 2
31, 2impbid2 195 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   wi 4   wb 176   wo 357
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-or 359
This theorem is referenced by:  biortn  395  pm5.61  693  pm5.55  867  cadan  1392  euor  2231  eueq3  3011  unineq  3505  ifor  3702  difprsnss  3846  eqtfinrelk  4486  dfphi2  4569
  Copyright terms: Public domain W3C validator