The MDL is a principle of data compression in Information Theory which states that, for a given dataset, the best model is the one which requires the minimum length (often measured in bits) to encode the model (the model description length) and the data (the data description length) (Rissanen, 1978).
the MDL principle captures the trade-o between the simplicity of a model, which is measured by t h e n umber of clusters in a tree-cut, and the goodness of t to the data, which is measured by the estimation accuracy of the probability distribution.