BLAST is a popular tool in NCBI website. There is no any doubt that it is a useful and effective tool in alignment, but based on survey in Qiime2 forum, I recognized Vesearch is widely used in classification. I read the two papers you suggested to me. The part I needed was mentioned in mathematics or algorithmic way, that I could not catch more. Yeah... you are right! I want simply to know which one is the best, Vesrach or Blast, although it sounds BLAST output represents that it works well in my case! I am just in dilemma, indeed!
Thanks your guidence in advance.
Qiimer