Probability vector

Here are examples of a probability vector:

x₀ = <math>

  \begin{bmatrix}
    .5 \\
    .25 \\
    .25
  \end{bmatrix}

x₁ = <math>

  \begin{bmatrix}
    0 \\
    1 \\
    0
  \end{bmatrix}

x₂ = <math>

  \begin{bmatrix}
    .65 \\
    .35
  \end{bmatrix}