The diameter of a conditional probability table \(P\) with \(n\) rows \(p_1,\dots,p_n\) is $$d^+(P)=\max_{i,j\leq n} d_V(p_i,p_j),$$ where \(d_V\) is the total variation distance between two probability mass functions over a sample space \(\mathcal{X}\), i.e. $$d_V(p_i,p_j)=\frac{1}{2}\sum_{x\in\mathcal{X}}|p_i(x)-p_j(x)|.$$