Metamath Proof Explorer


Theorem ibib

Description: Implication in terms of implication and biconditional. (Contributed by NM, 31-Mar-1994) (Proof shortened by Wolf Lammen, 24-Jan-2013)

Ref Expression
Assertion ibib φψφφψ

Proof

Step Hyp Ref Expression
1 pm5.501 φψφψ
2 1 pm5.74i φψφφψ