1. A method for a computer system to synthesize a sentence into an output language, the method comprising: obtaining a language-independent semantic structure of the sentence expressed as a language-independent directed acyclic graph including nodes, wherein the nodes correspond to semantic classes; selecting at least one lexical meaning from multiple lexical meanings in a corresponding semantic class for each node of the acyclic graph using: a lexical-semantic description of the output language, a rating related to lexical meanings in the output language, a rating related to combinations of the lexical meanings in the output language, and a most number of semantemes assigned to a constituent core of a corresponding word of the sentence, on the basis of the rating related to lexical meanings in the output language and the rating related to combinations of the lexical meanings in the output language; building a surface structure of the output sentence in the output language from the language-independent semantic structure using a syntactic description of the output language, wherein the surface structure of the output sentence is built at least in part based on a rating of syntactic constructions of the output language; restoring a movement and determining a linear order on the syntactic structure of the output sentence in the output language; and performing a morphological synthesis of the output sentence using morphological descriptions of the output language.