文摘
In this survey (functional) compositions of weighted tree transformations computable by weighted extended top-down tree transducers are investigated. The existing results in the literature are explained and illustrated. It is argued, why certain compositions are not possible in the general case, and 3?informed conjectures provide an insight into potentially 3?new composition results that extend and complement the existing results. In particular, if all were true, then the beautiful symmetry in the composition results for weighted top-down and bottom-up tree transducers would be recovered.