\nVdashThe symbol \nVdash is used in mathematical logic to denote that a statement or formula is not provable or does not entail another statement. It is the negation of the \Vdash symbol, which represents provability or entailment.
Statement A does not entail statement B
A \nVdash BThe set of statements \Gamma does not prove the formula \phi
\Gamma \nVdash \phiIt is not provable that there exists an x such that P(x) is true
\nVdash \exists x P(x)