To measure the quality of the inferred DTD, we use the concept of Minimum Message Length (MML) (Georgeff & Wallace 1984).
we adapt the formula developed for PFSA (Raman 1997) as below: where: • N is the number of states in the PFSA • V is the cardinality of the alphabet plus one • tj is the number of times the jth state is visited • mj is the number of arcs from the jth state (plus one for final states) • m j is the number of arcs from the jth state (no change for final states) • nij is the frequency of the ith arc from the jth state • M is the sum of all mj values and • M is the sum of all m j values One of the goals of this work was to both produce new inference methods and make comprehensive comparisons with existing techniques.