Syntax definition walsi

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)

	Ref	Expression
Assertion	walsi	$$wff\forall !x\left(\phi \to \psi \right)$$