Theorem pm4.71r 631

Description: Implication in terms of biconditional and conjunction. Theorem *4.71 of [WhiteheadRussell] p. 120 (with conjunct reversed). (Contributed by NM, 25-Jul-1999.)

Assertion

Ref	Expression
pm4.71r

Proof of Theorem pm4.71r

Step	Hyp	Ref	Expression
1		pm4.71 630	. 2
2		ancom 450	. . 3
3	2	bibi2i 313	. 2
4	1, 3	bitri 249	1

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

This theorem is referenced by:  pm4.71ri  633  pm4.71rd  635

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