Theorem pm2.49 281

Description: Theorem *2.49 of [WhiteheadRussell] p. 107.

Assertion

Ref	Expression
pm2.49	|- (-. (ph \/ ps) -> (-. ph \/ -. ps))

Proof of Theorem pm2.49

Step	Hyp	Ref	Expression
1		pm2.46 278	. 2 |- (-. (ph \/ ps) -> -. ps)
2	1	olcd 273	1 |- (-. (ph \/ ps) -> (-. ph \/ -. ps))

Syntax hints:  -. wn 2   -> wi 3   \/ wo 222

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 147  df-or 224

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