In terms of weighting scheme, the TextRank approach, which is more "strict" than tf-idf in eliminating unimportant words, has led comparatively higher retrieval performances on all levels of removal quantity when the translation model has been trained from the "noisy" (Q Q) corpus.
the "less strict" tf-idf approach has led better performances when the translation model has been trained from the "less noisy" (Q A) corpus.