Talk:Dempster-Shafer theory

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There are cases where it is better to model on something different than a probability space, but the examples given in the article are not. They don't even make sense: If all events are considered disjoint, so that p(red or blue) is meant to be the probability that a sensor gives the result "red or blue", then there is no need for a model of "belief" because one could just define the probabilities of all events to be the corresponding "beliefs" normalized by a constant (to get a "belief"-probability-space). If on the other hand p(red or blue) is the probability that the sensor gives a result "blue" or a result "red", then the example tables conflict with probability axioms p(A or B) >= max( p(A), p(B), meaning they can't represent a probability table.

The advantage of this theory is, that it allows the calculation of "belief values" of new events from known "belief values" of other events in other ways than the probability one. But if in the examples all events are considered separate (so they all add up to one), then the only difference to Probability Theory is that the "beliefs" don't add up to one ( which gives the same results multiplied by a constant -- very useless)

I wonder if whoever wrote this article, did understand probability theory or even what is the difference to Dempster-Shafer Theory?

Please!!! someone bring sense into this article!!!


Does anyone know if this stat has been implemented in a Arc9.+ GIS environemnt?


Is this a typo? "This means that it is possible that the cat is alive (should be dead??), up to 0.8, since the remaining probability mass of 0.3 is essentially "indeterminate," meaning that the cat could either be dead or alive."

I think that giving the vocabulary is important: - X should be called the Frame of reference - m should be called the Basic Belief Assignment.

The idea that belief and plausibility are respectively lower and upper bounds on some real, unknown probability is not unanimously accepted and should be presented as such.

Dempster's rule is usually denoted with \oplus. It is worth saying that it is commutative, associative and admits vacuous beliefs as identity.

I am surprised to notice that the criticism of this theory is well documented (even if it all comes from the same author) as compared to the theory itself. Another point is the fact that this article is part of the law project... I don't know much about Dempster-Shafer theory but I don't see in which way this could be related with law matters ????? Aurelein (talk) 15:01, 6 December 2007 (UTC)