Theorem biimpr 129

Description: Property of the biconditional connective. (Contributed by NM, 11-May-1999.) (Proof shortened by Wolf Lammen, 11-Nov-2012.)

Assertion

Ref	Expression
biimpr	|- ( ( ph <-> ps ) -> ( ps -> ph ) )

Proof of Theorem biimpr

Step	Hyp	Ref	Expression
1		df-bi 116	. . 3 |- ( ( ( ph <-> ps ) -> ( ( ph -> ps ) /\ ( ps -> ph ) ) ) /\ ( ( ( ph -> ps ) /\ ( ps -> ph ) ) -> ( ph <-> ps ) ) )
2	1	simpli 110	. 2 |- ( ( ph <-> ps ) -> ( ( ph -> ps ) /\ ( ps -> ph ) ) )
3	2	simprd 113	1 |- ( ( ph <-> ps ) -> ( ps -> ph ) )

Syntax hints:   -> wi 4   /\ wa 103   <-> wb 104

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106

This theorem depends on definitions:  df-bi 116

This theorem is referenced by:  bicom1  130  pm5.74  178  bi3ant  223  pm5.32d  446  notbi  656  nbn2  687  pm4.72  813  con4biddc  843  con1biimdc  859  bijadc  868  pclem6  1356  exbir  1416  simplbi2comg  1423  albi  1448  exbi  1584  equsexd  1709  cbv2h  1728  cbv2w  1730  sbiedh  1767  ceqsalt  2738  spcegft  2791  elab3gf  2862  euind  2899  reu6  2901  reuind  2917  sbciegft  2967  iota4  5154  fv3  5492  algcvgblem  11930  bj-inf2vnlem1  13587