Theorem pm4.67 428

Description: Theorem *4.67 of [WhiteheadRussell] p. 120. (Contributed by NM, 3-Jan-2005.)

Assertion

Ref	Expression
pm4.67

Proof of Theorem pm4.67

Step	Hyp	Ref	Expression
1		pm4.63 421	1

Syntax hints:  -.wn 3  ->wi 4  <->wb 184  /\wa 369

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 185  df-an 371