 The MDL principle is often referred to as a modern version of Ockham’s razor (see entry on  William of Ockham),  although in its original form Ockham’s razor is an ontological principle and has little to do with data compression. In many cases MDL is a valid heuristic tool and the mathematical properties of the theory have been studied extensively (Grünwald 2007). Still MDL, Ockham’s razor and two-part code optimization have been the subject of considerable debate in the past decennia (e.g., Domingos 1998; McAllister 2003). 