\vdashThe symbol \vdash is used in logic and mathematics to denote syntactic entailment or derivability. It indicates that a particular statement or formula can be derived from a set of axioms or premises.
Statement B is derivable from statement A.
A \vdash BThe formula \phi is derivable from the set of premises \Gamma.
\Gamma \vdash \phiThe formula \neg (P \land \neg P) is a theorem, derivable without any premises.
\vdash \neg (P \land \neg P)