Re: [higgins-dev] Higgins data model for attribute values

[Greg Byrd <gbyrd@xxxxxxxx>]

One point that Mike's bringing up (I think) is the difference between not having an attribute, and having an attribute without a value.  In the latter case, there's a definite statement that we have no knowledge of this particular attribute.  (If, for example, we know that a person has no driver's license.)  If the attribute is missing, we can't know whether it's because there is no such attribute for this subject, or whether we just don't know anything about it.

In OWL, I think you'd have to have an explicit value that means "unknown", because you have to have a value associated with a property.  This may or may not be represented in the same way in the IdAS model.

...Greg




Michael McIntosh wrote:

higgins-dev-bounces@xxxxxxxxxxx wrote on 01/04/2008 09:19:47 PM:

  

Before addressing bug #190594, I need to know more about what the
Higgins data model allows in an attribute's instance data.

In IdAS, my understanding is that a Digital Subject may have 0..1
occurrence of a particular Attribute, and that an Attribute may have
1..N occurrences of a particular type of Value.
    

In the case of an Attribute X, I would like to better understand the
semantic intended by the difference between the two cases where:
a) there is 0 occurence of X,,
b) there is 1 occurence of X with 0 values.
Is there a difference? What is it?

If this model changed to allow 0..N occurence of an Attribute, with 1
occurence of Value for each Attribute, what would be the difference?

If this model changed to allow 1 occurence of an Attribute, with 0..N
occurence of Value for each Attribute, what would be the difference?

  

It's my understanding that each of an Attribute's values must be of
the same data type, but that restriction isn't obvious to me in the
Higgins OWL, and in fact, the opposite is reflected in the IdAS
APIs.  In IdAS, one can state the data type of each value they add
to an attribute.

So, we need to agree on the Higgins data model regarding the types
of attribute values.  Should the Higgins data model dictate that
they all be of the same type, or should it allow their types to be mixed?
    

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