RE: Model and sources of uncertainty

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.
 
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.
 
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).
 
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.
 
Vipul's issues:
 
Statement vs. belief: Perhaps we could incorporate beliefs in the ontology,
but this would seem to say that someone makes statements that he/does not
believe in. It seems to me that in that case the distinction would be
between the agent who believes in the statment and someone else who just
refers to that agent's beliefs. We could possibly subclassify Statement for
this purpose. Vipul - could you say in OWL what changes you are proposing?
 
I agree that UncertaintyModel could be termed somehow differently. We could
possibly add some synonims to the ontology.
 
It seems that the rest Vipul's statements are comments or clarifications. 
 
==Mitch
 
 
 


  _____  

From: public-xg-urw3-request@w3.org [mailto:public-xg-urw3-request@w3.org]
On Behalf Of Paulo CG Costa
Sent: Thursday, June 14, 2007 5:59 AM
To: public-xg-urw3@w3.org
Subject: Model and sources of uncertainty


Dear Mitch, 

The model on types of uncertainty lists only three of them:
1 - Vagueness
2 - Randomness
3 - Ambiguity

How about:
- unreability: knowledge from a source that is not 100% trustfull,
- dissonance: we see the same piece of information, but each have a distinct
interpretation,
- incompleteness: which is not vagueness, since you can have a clear view of
just part of the information,
- inconclusiveness: we have clear, deterministic, non ambiguous information,
which is also complete, we both agree upon it, and the source is reliable,
but it is not enough to come up with any conclusive assertion.

Also, regarding the sources of uncertainty, how about interpretation? Is it
within the epistemic label?
I know that our lack of complete knowledge of the things that happen in the
world (even if they are deterministic) is the cause of (epistemic)
uncertainty. However, it is not so clear to me that two people with complete
knowledge about a deterministic phenomena, but with distinct interpretations
of what they see are an epistemic source of uncertainty.
The uncertainty doesn't come from an aleatory source and is not caused by
incomplete knowledge, but it is an artifact of how those human sensors
perceive the phenomena.

Thanks,
Paulo





_______________________________
Dr. Paulo Cesar G. da Costa
Assistant Professor - C4I Center
George Mason University
Fairfax, VA - USA
 <http://mason.gmu.edu/~pcosta> http://mason.gmu.edu/~pcosta
 <mailto:pcosta@gmu.edu> pcosta@gmu.edu