Theorem oridmOLD 463

Description: Obsolete proof of oridm 461.

Assertion

Ref	Expression
oridmOLD	|- ((ph \/ ph) <-> ph)

Proof of Theorem oridmOLD

Step	Hyp	Ref	Expression
1		df-or 338	. 2 |- ((ph \/ ph) <-> (-. ph -> ph))
2		pm4.81 308	. 2 |- ((-. ph -> ph) <-> ph)
3	1, 2	bitri 279	1 |- ((ph \/ ph) <-> ph)

Syntax hints:  -. wn 2   -> wi 3   <-> wb 219   \/ wo 336

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7

This theorem depends on definitions:  df-bi 220  df-or 338

Copyright terms: Public domain