Re: Model and sources of uncertainty

Hello Mitch, Vipul, and All,

> So first of all I'd like to say that all I tried to do is read a  
> couple of papers (two of them are listed on the web site) that  
> discuss various types of uncertainty and then make an attempt at  
> reconciling multiple views of the terms used in the various  
> approaches into a single ontology. In other words, the notions I  
> put in the ontology are not my inventions - they are defined in  
> various papers.

So did I. All the stuff about evidence came from David Schum's book  
(already mentioned by Kathy) and numerous papers. He is a well known  
expert in evidential reasoning.

>
> During this weekend I tried to understand the feedback I received  
> from the group and then tried to see whether the current ontology  
> is sufficient or it needs to be extended. I came to the conlcusion  
> that we might need to extend it a bit. I have not made the changes  
> in the graphics, as yet, since I didn't want to put too much effort  
> into the changes before first coming to some agreements.
>
> However, in order to make the discussion more focused, I added some  
> textual descriptions of the terms used in the ontology (on the Wiki).
>
> So here are my replies to the issues raised by the group, mainly by  
> Paulo and Vipul. I believe gstoil is in agreement with me.
>
> 1. Unreliability of the source: In the current Uncertainty  
> Reasoning Ontology, let's call it URO for now, this would be  
> modeled by representing the source as an instance of World. Thus  
> there would be a sentence about the source A  "Source A is 33%  
> reliable." Then the notion of "33% reliable" would have to be  
> specified using one of the Uncertainty Types.

My main issue with the graph is that I see uncertainty as a  
characteristic of a given phenomena, not as a phenomena by itself. As  
an example, a deterministic phenomenon can be perceived as uncertain  
due to lack of knowledge about it, to a biased or limited perception,  
or to any other cause that prevents our complete understating about  
it. On the other hand, we might have complete information about a  
phenomenon and still remain unable to tell its outcome, given the  
intrinsically stochastic nature of that phenomenon. I called the  
first case as an epistemic "kind of uncertainty", and the second case  
as an existential "kind of uncertainty". Thus, when defining types of  
uncertainty, I'd list the above two.
I see all the terms that you list here (from 1 to 5) as  
characteristics of the information we have about a given phenomena  
that might lead us to label it uncertain. Thus, these are in fact  
sources of uncertainty, not types of uncertainty.

>
> 2. Dissonance: I added one more type to UncertaintyTypes -  
> Inconsistency. I believe this would capture dissonance, but if not,  
> we could then think a bit more about this issue. I mean here  
> logical inconsistency, i.e., when there is no model for a sentence.  
> I don't mean existence of evidence for and against a specific  
> hypotheses (which is just fine within the probability theory).

Dissonance captures both contradictory and conflicting evidence.  
Inconsistency happens when a KB has two axioms that imply mutually  
exclusive hypothesis.

>
> 3. Incompleteness: I would also say that incompleteness is not a  
> type of vagueness. But it might be interpreted as a kind of  
> ambiguity due to the lack of sufficient information for resolving  
> the question of whether a specific world is a model of the sentence  
> or not. But then we could also add another class (Incompleteness)  
> to the types of uncertainty.
>
> 4. Inconclusiveness: I believe I understand what it is, but I don't  
> quite see how this is a type of uncertainty. Perhaps I am missing  
> something here? But it looks to me more like redundancy, i.e., a  
> sentence does not add to the existing knowledge since it's already  
> in what can be inferred from the knowledge we already have. Please  
> correct me if I am wrong on this.
>
> 5. Interpretation: I believe this is about sensors through which we  
> perceive the world. Similary as in point 1 above, this is a  
> sentence about an instance of World (sensor) whose accuracy would  
> have to be specified in terms of this ontology using one of the  
> probability types.

As I implied above, I don't see any of those as types of uncertainty,  
but as characteristics of evidence that result in uncertainty about  
an event. We sense the world with sensors, the output of the sensors  
can be seen as evidence we have on how the world actually is. If we  
have imperfect information from our sensors we will have uncertainty  
about the phenomenon they're sensing.

Cheers,
Paulo

>