28. A method of determining a score for a word string, the method comprising: using a processor to compute an input semantic structure having a plurality of nodes that relate to an input word string; using the processor to obtain a set of transfer mappings, each of the set of transfer mappings including an input semantic side that describes at least one node of the input semantic structure; and using the processor to score each of the set of transfer mappings which cover at least a select node of the input semantic structure with a target language model that provides a probability of sequences of nodes appearing in an output semantic structure having a plurality of nodes that relate to an output word string, wherein scoring each transfer mapping comprises combining the highest scoring mappings for each child node of the select node not covered by the transfer mapping with the score of the transfer mapping; and using the processor to select the highest scoring transfer mappings of the set of transfer mappings which cover at least the select node to compute the output semantic structure that relates to the output word string.
28. A method of determining a score for a word string, the method comprising: using a processor to compute an input semantic structure having a plurality of nodes that relate to an input word string; using the processor to obtain a set of transfer mappings, each of the set of transfer mappings including an input semantic side that describes at least one node of the input semantic structure; and using the processor to score each of the set of transfer mappings which cover at least a select node of the input semantic structure with a target language model that provides a probability of sequences of nodes appearing in an output semantic structure having a plurality of nodes that relate to an output word string, wherein scoring each transfer mapping comprises combining the highest scoring mappings for each child node of the select node not covered by the transfer mapping with the score of the transfer mapping; and using the processor to select the highest scoring transfer mappings of the set of transfer mappings which cover at least the select node to compute the output semantic structure that relates to the output word string. 29. The method of claim 28 , wherein providing an input semantic structure having a plurality of nodes comprises providing an input semantic structure having a plurality of word nodes and at least one relationship node that describes a semantic relationship between words.