Metamath Proof Explorer

Theorem truimfal

Description: A -> identity. (Contributed by Anthony Hart, 22-Oct-2010) (Proof shortened by Andrew Salmon, 13-May-2011)

Ref Expression
Assertion truimfal 
|- ( ( T. -> F. ) <-> F. )

Proof

Step Hyp Ref Expression
1 trut 
 |-  ( F. <-> ( T. -> F. ) )
2 1 bicomi 
 |-  ( ( T. -> F. ) <-> F. )