Belief Calculus
  In Dempster-Shafer belief theory, general beliefs are expressed as belief
mass distribution functions over frames of discernment. In Subjective Logic
beliefs are expressed as belief mass distribution functions over binary frames
of discernment. Belief representations in Subjective Logic, which are called
opinions, also contain a base rate parameter which express the a priori belief
in the absence of evidence. Philosophically, beliefs are quantitative
representations of evidence as perceived by humans or by other intelligent
agents. The basic operators of classical probability calculus, such as addition
and multiplication, can be applied to opinions, thereby making belief calculus
practical. Through the equivalence between opinions and Beta probability
density functions, this also provides a calculus for Beta probability density
functions. This article explains the basic elements of belief calculus.
