Computing the relative entropy between regular tree languages

Stochastic grammars provide a formal background in order to deal with tasks where a random source of structured data is involved. In particular, stochastic tree grammars can be useful if hierarchical relations are established among the elementary components of the data. Grammatical inference methods are often checked with training samples generated by a known grammar which is later compared to the grammar inferred from the sample. One measure of their similarity is given by the relative entropy between both grammars. In this paper, we describe an efficient procedure to compute the relative entropy between two stochastic deterministic regular tree grammars. (C) 1998 Elsevier Science B.V. All rights reserved.