We propose a posterior distribution for which the latent partition is restricted to a special numbering leading to the largest separation with its permutations. Two different measures of separation are proposed, the first one being global but intractable even from very small sample sizes (Kullback divergence), the second one being local and thus very easy to compute (difference of distributions at the MAP). A Gibbs algorithm allows to sample easily according to this new distribution. This procedure is general enough to apply directly with any distribution and some experiments in Gaussian and multinomial settings show particularly encouraging results.