Description: A universal specialization result in deduction form, proved from ax-1 -- ax-6 , where the only DV condition is on x , y and where x should be nonfree in the new proposition ch (and in the context ph ). (Contributed by BJ, 4-Apr-2026)
|- ( ph -> A. x ph )
|- ( ph -> ( E. x ch -> ch ) )
|- ( ( ph /\ x = y ) -> ( ps -> ch ) )
|- ( ph -> ( A. x ps -> ch ) )
|- E. x x = y
|- ( ph -> E. x x = y )