Theorem pm2.45 386

Description: Theorem *2.45 of [WhiteheadRussell] p. 106. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm2.45	|- (-. (ph \/ ps) -> -. ph)

Proof of Theorem pm2.45

Step	Hyp	Ref	Expression
1		orc 374	. 2 |- (ph -> (ph \/ ps))
2	1	con3i 127	1 |- (-. (ph \/ ps) -> -. ph)

This proof depends on syntax axioms:  -. wn 3   -> wi 4   \/ wo 357

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This proof depends on definitions:  df-bi 177  df-or 359

This theorem is used by:  pm2.47  388  dn1  932  eueq3  3012