Thanh Nguyen writes:

Could you tell me what is the difference between “uncertainty” and “ignorance” in this theory [of belief functions]? Some authors define “ignorance” as the “uncommitted belief” which is assigned to the whole frame of discernment, others define it as the difference between Plausibility and Belief (Pl() – Bel()). Some authors define value assigned by Belief function for elements as “uncertainty”.

I don’t know. All I know about belief functions is in my article about the boxer, the wrestler, and the coin flip, which is actually a writeup of something I did 20 years ago. So no new thoughts, unfortunately.