number of tokens in the source number of tokens in the target ratio of source and target sentences lenght target word left context of the target word right context of the target word source word aligned to the target word left context of the aligned source word right context of the aligned source word target word is stopword target word is punctuation mark target word is proper noun target word is digit highest order of ngram that includes target word and its left context highest order of ngram that includes target word and its right context backoff behavior of ngram w_{i-2} w_{i-1} w_{i} (w_{i} - target word) backoff behavior of ngram w_{i-1} w_{i} w_{i+1} backoff behavior of ngram w_{i} w_{i+1} w_{i+2} highest order of ngram that includes source word and its left context highest order of ngram that includes source word and its right context POS of the target word POS of the aligned source word target word + left context target word + right context target word + aligned source word POS of target word + POS of aligned source word target word + left context + source word target word + right context + source word