Predicted T on simulation data without and with group constraints. In the upper panel, we plotted the estimated concentrations of the three transcripts generated by Wang et al.'s deconvolution procedure without group constraints  (denoted by the circles). Note that every solution achieves a global minimum of the log-likelihood function, but they are quite different and none of them approximates the true T(denoted by the triangles). The lower panel shows the unique estimate using (four) group constraints; it is very close to the true T, even though the noise is large and there is some unknown background signal.