2836	 Weighted Derivation Trees	 The nodes of a weighted derivation tree are associated with weighting functions over the vocabulary of a context-free grammar. An algorithm is presented for constructing the optimal derivation tree having the same structure as a given weighted derivation tree. In addition the correctness of the algorithm is established. The method may be applied to problems involving probabilistic parsing or combinatorial optimization. derivation tree parse tree probabilistic grammar structural ambiguity combinatorial optimization
