the performance of DE and its variants is largely better than the PSO variants over a wide variety of problems as has been indicated by studies like ......
句中的as像是關系代詞,相當于which,但是我在百度上查了一下,沒見到as可以引導限定性定語從句,as好像都是引導非限定性定語從句。這個as是引導限定性定語從句嗎?