Metamath Proof Explorer

Theorem nanan

Description: Conjunction in terms of alternative denial. (Contributed by Mario Carneiro, 9-May-2015)

Ref Expression
Assertion nanan 
|- ( ( ph /\ ps ) <-> -. ( ph -/\ ps ) )

Proof

Step Hyp Ref Expression
1 df-nan 
 |-  ( ( ph -/\ ps ) <-> -. ( ph /\ ps ) )
2 1 con2bii 
 |-  ( ( ph /\ ps ) <-> -. ( ph -/\ ps ) )