Syntax Definition walsi 15720

Description: Extend wff definition to include "all some" applied to a top-level implication, which means ps is true whenever ph is true, and there is at least least one x where ph is true. (Contributed by David A. Wheeler, 20-Oct-2018.)

Hypotheses

Ref	Expression
wph	wff ph
wps	wff ps
vx	setvar x

Assertion

Ref	Expression
walsi	wff A.! x ( ph -> ps )

See definition df-alsi 15722 for more information.