Abstract: In this paper, we discussed a kind of comparison theory introduced by Lin Huaxin. We first used operator theory to discuss hiding information in the original definition and then obtain an equivalent definition of this comparison theory. Also, some useful properties and results are presented. In addition, we gave an interesting property about projections that it does not have and a characterization of simple C*-algebras.

Key words: positive element, comparison theory, C*-algebra, positive element, comparison theory