“…Dimensionality reduction has been a critical preprocessing step in many fields of information processing and analysis, such as data mining [5,12,[18][19][20], information retrieval [14,16], and pattern recognition [11,21,29,37]. Recently, with the advances of computer technologies and the development of the World Wide Web, a huge amount of digital data, including text, images and videos, is generated, stored, analyzed, and accessed every day.…”