Some Properties of Query Languages for Bags

  title={Some Properties of Query Languages for Bags},
  author={Leonid Libkin and Limsoon Wong},
In this paper we study the expressive power of query languages for nested bags. We deene the ambient bag language by generalizing the constructs of the relational language of Breazu-Tannen, Buneman and Wong, which is known to have precisely the power of the nested relational algebra. Relative strength of additional polynomial constructs is studied, and the ambient language endowed with the strongest combination of those constructs is chosen as a candidate for the basic bag language, which is… CONTINUE READING