19. A translation system comprising: a decoder which receives as input a source text string in a source language and outputs a translated text string in a target language in a target language, based on the source text string; a merging system, which receives the translated text string and outputs a translation in the target language based on translated text string, the merging system being configured for outputting decisions on merging of pairs of words in the translated text string, the merging system comprising at least one of: a set of stored heuristics comprising at least a first heuristic by which two consecutive words in the string are considered for merging if the observed frequency f 1 of the two consecutive words as a closed compound word is larger than an observed frequency f 2 of the two consecutive words as a bigram, and, optionally, if the first word of the two consecutive words is also recognized as a compound modifier, and a merging model trained on features associated with pairs of consecutive tokens of text strings in a training corpus and predetermined merging decisions for the pairs to predict merging decisions for a new translated text string.
21. The system of claim 19 , further comprising memory which stores a list of closed compounds in the training corpus and their associated frequencies f 1 and f 2 .