TeX source:

l(A, B)=\frac{1}{2 n} \sum_{i=1}^{n}\left[\begin{array}{l}\left|\mathbf{\mu}_{A}(x)-\boldsymbol{\mu}_{B}(x)\right|+ \\\left|\nu_{A}(x)-\nu_{B}(x)\right|+ \\\left|\pi_{A}(x)-\pi_{B}(x)\right|\end{array}\right] \frac{1}{2}