Theorem biimpr 130

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 117	. . 3 |- ( ( ( ph <-> ps ) -> ( ( ph -> ps ) /\ ( ps -> ph ) ) ) /\ ( ( ( ph -> ps ) /\ ( ps -> ph ) ) -> ( ph <-> ps ) ) )
2	1	simpli 111	. 2 |- ( ( ph <-> ps ) -> ( ( ph -> ps ) /\ ( ps -> ph ) ) )
3	2	simprd 114	1 |- ( ( ph <-> ps ) -> ( ps -> ph ) )

Syntax hints:   -> wi 4   /\ wa 104   <-> wb 105

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107

This theorem depends on definitions:  df-bi 117

This theorem is referenced by:  bicom1  131  pm5.74  179  bi3ant  224  pm5.32d  450  notbi  672  nbn2  704  pm4.72  834  con4biddc  864  con1biimdc  880  bijadc  889  pclem6  1418  exbir  1481  simplbi2comg  1488  albi  1516  exbi  1652  equsexd  1777  cbv2h  1796  cbv2w  1798  sbiedh  1835  ceqsalt  2829  spcegft  2885  elab3gf  2956  euind  2993  reu6  2995  reuind  3011  sbciegft  3062  iota4  5306  fv3  5662  algcvgblem  12620  bj-inf2vnlem1  16565