Theorem pm4.62 408

Description: Theorem *4.62 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm4.62	|- ((ph -> -. ps) <-> (-. ph \/ -. ps))

Proof of Theorem pm4.62

Step	Hyp	Ref	Expression
1		imor 401	1 |- ((ph -> -. ps) <-> (-. ph \/ -. ps))

This proof depends on syntax axioms:  -. wn 3   -> wi 4   <-> wb 176   \/ 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:  ianor  474  rb-bijust  1514