In both cases, the sentences were automatically aligned from comparable English Wikipedia and Simple English Wikipedia articles.
the use of EW-SEW dataset for modeling TS has been disputed (Amancio and Specia, 2014;Štajner et al., 2015;Xu et al., 2015) for several reasons: (1) the simplified articles are not necessarily direct simplifications of the original articles; (2) the quality of simplifications is not checked; (3) the dataset does not cover sentence splitting which is one of the most common operations in text simplification.