Theorem biimt 239

Description: A wff is equivalent to itself with true antecedent. (Contributed by NM, 28-Jan-1996.)

Assertion

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

Proof of Theorem biimt

Step	Hyp	Ref	Expression
1		ax-1 5	. 2 |- ( ps -> ( ph -> ps ) )
2		pm2.27 39	. 2 |- ( ph -> ( ( ph -> ps ) -> ps ) )
3	1, 2	impbid2 141	1 |- ( ph -> ( ps <-> ( ph -> ps ) ) )

Syntax hints:   -> wi 4   <-> wb 103

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106

This theorem depends on definitions:  df-bi 115

This theorem is referenced by:  pm5.5  240  a1bi  241  abai  524  dedlem0a  909  ceqsralt  2626  reu8  2788  csbiebt  2942  r19.3rm  3330  fncnv  4985  ovmpt2dxf  5646  brecop  6219