Theorem pm2.1 406

Description: Theorem *2.1 of [WhiteheadRussell] p. 101. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 23-Nov-2012.)

Assertion

Ref	Expression
pm2.1	|- (-. ph \/ ph)

Proof of Theorem pm2.1

Step	Hyp	Ref	Expression
1		id 19	. 2 |- (ph -> ph)
2	1	imori 402	1 |- (-. ph \/ ph)

Syntax hints:  -. wn 3   \/ 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:  nchoicelem9  6298  nchoicelem18  6307