 Formulas of the form \(Px (\phi) \geq q\) should be read as: “the probability of selecting an \(x\) such that \(x\) satisfies \(\phi\) is at least \(q\)”. The formula \(Px(\phi) \leq q\) is an abbreviation of \(Px(\neg \phi) \geq 1-q\) and \(Px(\phi)=q\) is an abbreviation of \(Px(\phi) \geq q \wedge Px(\phi) \leq q\). Every free occurrence of \(x\) in \(\phi\) is bound by the operator.