Theorem biorfiOLD 423

Description: Obsolete proof of biorfi 422 as of 16-Jul-2021. (Contributed by NM, 23-Mar-1995.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
biorfi.1	|- -. ph

Assertion

Ref	Expression
biorfiOLD	|- ( ps <-> ( ps \/ ph ) )

Proof of Theorem biorfiOLD

Step	Hyp	Ref	Expression
1		biorfi.1	. 2 |- -. ph
2		orc 400	. . 3 |- ( ps -> ( ps \/ ph ) )
3		orel2 398	. . 3 |- ( -. ph -> ( ( ps \/ ph ) -> ps ) )
4	2, 3	impbid2 216	. 2 |- ( -. ph -> ( ps <-> ( ps \/ ph ) ) )
5	1, 4	ax-mp 5	1 |- ( ps <-> ( ps \/ ph ) )

Syntax hints:   -. wn 3   <-> wb 196   \/ wo 383

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 197  df-or 385

This theorem is referenced by: (None)