\mu_j\)</span> and <span class="math inline">\(\sigma_i = \sigma_j\)</span> for <span class="math inline">\(i \neq j\)</span>.</p>
<p>This will typically happen early in sampling due to initialization in
MCMC or optimization or arise from random movement during MCMC. Once
the parameters match for a given draw <span class="math inline">\((m)\)</span>, it can become hard to
escape because there can be a trough of low-density mass between the
current parameter values and the ones without collapsed components.<