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Syntax Definition walsi 42407
Description: Extend wff definition to include "all some" applied to a top-level implication, which means 𝜓 is true whenever 𝜑 is true, and there is at least least one 𝑥 where 𝜑 is true. (Contributed by David A. Wheeler, 20-Oct-2018.)
Hypotheses
Ref Expression
wph wff 𝜑
wps wff 𝜓
vx setvar 𝑥
Assertion
Ref Expression
walsi wff ∀!𝑥(𝜑𝜓)

See definition df-alsi 42409 for more information.

Colors of variables: wff setvar class
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