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 ∀! 𝑥 ( 𝜑 → 𝜓 ) |