Metamath Proof Explorer

Theorem pm3.14

Description: Theorem *3.14 of WhiteheadRussell p. 111. (Contributed by NM, 3-Jan-2005)

Ref Expression
Assertion pm3.14 
|- ( ( -. ph \/ -. ps ) -> -. ( ph /\ ps ) )

Proof

Step Hyp Ref Expression
1 pm3.1 
 |-  ( ( ph /\ ps ) -> -. ( -. ph \/ -. ps ) )
2 1 con2i 
 |-  ( ( -. ph \/ -. ps ) -> -. ( ph /\ ps ) )