Theorem biorfi 407

Description: A wff is equivalent to its disjunction with falsehood. (Contributed by NM, 23-Mar-1995.)

Hypothesis

Ref	Expression
biorfi.1

Assertion

Ref	Expression
biorfi

Proof of Theorem biorfi

Step	Hyp	Ref	Expression
1		biorfi.1	. 2
2		orc 385	. . 3
3		orel2 383	. . 3
4	2, 3	impbid2 204	. 2
5	1, 4	ax-mp 5	1

Syntax hints:  -.wn 3  <->wb 184  \/wo 368

This theorem is referenced by:  pm4.43  927  dn1  966  stoic1a  1605  indifdir  3753  un0  3810  opthprc  5052  imadif  5668  xrsupss  11529  mdegleb  22464  ind1a  28034  bj-ifid2  37711  bj-ifnot  37717  bj-ifdfan  37727

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 185  df-or 370