Metamath Proof Explorer

Theorem bj-nexrt

Description: Closed form of nexr . Contrapositive of 19.8a . (Contributed by BJ, 20-Oct-2019)

Ref Expression
Assertion bj-nexrt 
|- ( -. E. x ph -> -. ph )

Proof

Step Hyp Ref Expression
1 19.8a 
 |-  ( ph -> E. x ph )
2 1 con3i 
 |-  ( -. E. x ph -> -. ph )