 As an example, consider a model of a vase containing nine marbles: five are black and four are white. Let us assume that \(P\) assigns a probability of 1/9 to each marble, which captures the idea that one is equally likely to pick any marble. Suppose the language contains a unary predicate \(B\) whose interpretation is the set of black marbles. The sentence \(Px(B(x)) = 5/9\) is true in this model regardless of the assignment.