A geometric approach to conditioning belief functions

TL;DR

This paper introduces a geometric method for conditioning belief functions by projecting them onto a simplex, simplifying interpretation and potentially unifying classical conditioning approaches within a geometric framework.

Contribution

It proposes a novel geometric approach to belief function conditioning, offering simpler, interpretable results and exploring connections to classical methods like Dempster's conditioning.

Findings

Geometric conditioning often yields simple, interpretable results.

The approach suggests a potential unification with classical conditioning methods.

Future work includes studying combination rules derived from geometric conditioning.

Abstract

Conditioning is crucial in applied science when inference involving time series is involved. Belief calculus is an effective way of handling such inference in the presence of epistemic uncertainty -- unfortunately, different approaches to conditioning in the belief function framework have been proposed in the past, leaving the matter somewhat unsettled. Inspired by the geometric approach to uncertainty, in this paper we propose an approach to the conditioning of belief functions based on geometrically projecting them onto the simplex associated with the conditioning event in the space of all belief functions. We show here that such a geometric approach to conditioning often produces simple results with straightforward interpretations in terms of degrees of belief. This raises the question of whether classical approaches, such as for instance Dempster's conditioning, can also be reduced to some form of distance minimisation in a suitable space. The study of families of combination rules generated by (geometric) conditioning rules appears to be the natural prosecution of the presented research.