  The joint PLDA model, is a generalization of PLDA where the nuisance variable
is no longer considered independent across samples, but potentially shared
(tied) across samples that correspond to the same nuisance condition. The
original work considered a single nuisance condition, deriving the EM and
scoring formulas for this scenario. In this document, we show how to obtain
likelihood ratios for scoring when multiple nuisance conditions are allowed in
the model.
