{"gt_parse": {"text_sequence": "if and o nly i f it i s right unitar y.Fac torization.A factorization of a free m onoid is a sequence of subsets of words with the property that every word in the free monoid can be written as a co ncatenati on of e lement s drawn from th e subs ets. Th e Che n–Fox–L yndon t heorem st ates tha t the Lyn don wor ds fur nish a f"}}