Edited sentence: Consider the following example: If we totally have no information about the coin, in probability theory, we will assume that it would be 50% head and 50% tail.Dempster-Shafer theory can effectively solve this problem.For example, the ignorance.However, in other scenario, we know the coin is fair, so we have the clear conclusion that, it would be 50% head and 50% tail.However, there are some information probability cannot describe.It seems that the well known probability theory can effectively model the uncertainty.Therefore, in two scenario, we lead the same conclusion, how we present totally ignorance in probability theory becomes a problem