Characters and States and GUIDs and descriptive data

Wed Jan 25 11:35:00 CET 2006

Kevin mentioning Characters and States and GUIDs got me thinking and I
was wondering if we could cover something along these lines before the
meeting. Please excuse me if this has been dealt with on the list. I
will use a Delta type illustration to my point. This may not apply to
SDD so much - apologies if it doesn't but I am trying to get at a
general point. My comments may be more general to GUIDs though...

When we are dealing with GUIDs we are talking in an Open World model as
opposed to a Closed World model. If I search Google (open world) and
don't find something it isn't because it doesn't exist - it may exist
but not be found for a host of reasons. If I search my local SQL DB
(closed world) and I don't find something then I can safely assume it
isn't there. (This may be a naive description of Open vs Close worlds
but it illustrates the point).

Taking this to the Characters/States model. We have a character that
looks like this:

Flower Colour (GUID_c01)
- red (GUID_s01)
- white (GUID_s02)
- yellow (GUID_s03)

And I score a taxon as  "Rose *has* flower colour red". If I have given
GUIDs to the states then I don't need to use the GUID for the character.
"Rose has s01" is fine as the character is implied.

Can we assume from this statement that my rose does not have white or
yellow flowers? Yes - but only if it is a closed world and we know that
the character never changes (or hasn't changed since the date of the
assertion). If the choice when scoring had been:

Flower Colour (GUID_c01)
- red (GUID_s01)
- white (GUID_s02)
- yellow (GUID_s03)
- dark pink (GUID_s99)

I may have chosen "Rose has s99" of "Rose has s99 and s01" but I simply
didn't have that choice before.

So the thing that is troubling me is that Character/State uses a closed
world model where not finding something implies that it doesn't have
that attribute. In an open world system one can only draw conclusions
from presence not absence. We could give GUIDs to characters and states
but it doesn't get us very far as it doesn't permit us to re-use or
extend them in a simple way. (sure you could build an inheritance model
for characters and states but this rapidly becomes a complete ontology
language of which there are a few already available!).

My gut feeling is that in the long term the Character/State model
doesn't transfer well into an open world model. I suspect this problem
may occur in other descriptive areas where the existing model specifies
noun-adjective pairs that I don't have experience of. Perhaps we could
explore this a little. Perhaps my guts need straightening out!

Your thoughts greatly appreciated.

Roger

--

-------------------------------------
 Roger Hyam
 Technical Architect
 Taxonomic Databases Working Group
-------------------------------------
 http://www.tdwg.org
 roger at tdwg.org
 +44 1578 722782
-------------------------------------

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<br>
Kevin mentioning Characters and States and GUIDs got me thinking and I
was wondering if we could cover something along these lines before the
meeting. Please excuse me if this has been dealt with on the list. I
will use a Delta type illustration to my point. This may not apply to
SDD so much - apologies if it doesn't but I am trying to get at a
general point. My comments may be more general to GUIDs though...<br>
<br>
When we are dealing with GUIDs we are talking in an Open World model as
opposed to a Closed World model. If I search Google (open world) and
don't find something it isn't because it doesn't exist - it may exist
but not be found for a host of reasons. If I search my local SQL DB
(closed world) and I don't find something then I can safely assume it
isn't there. (This may be a naive description of Open vs Close worlds
but it illustrates the point).<br>
<br>
Taking this to the Characters/States model. We have a character that
looks like this:<br>
<br>
Flower Colour (GUID_c01)<br>
- red (GUID_s01)<br>
- white (GUID_s02)<br>
- yellow (GUID_s03)<br>
<br>
And I score a taxon as&nbsp; "Rose <b>has</b> flower colour red". If I have
given GUIDs to the states then I don't need to use the GUID for the
character. "Rose has s01" is fine as the character is implied.<br>
<br>
Can we assume from this statement that my rose does not have white or
yellow flowers? Yes - but only if it is a closed world and we know that
the character never changes (or hasn't changed since the date of the
assertion). If the choice when scoring had been:<br>
<br>
Flower Colour (GUID_c01)<br>
- red (GUID_s01)<br>
- white (GUID_s02)<br>
- yellow (GUID_s03)<br>
- dark pink (GUID_s99)<br>
<br>
I may have chosen "Rose has s99" of "Rose has s99 and s01" but I simply
didn't have that choice before. <br>
<br>
So the thing that is troubling me is that Character/State uses a closed
world model where not finding something implies that it doesn't have
that attribute. In an open world system one can only draw conclusions
from presence not absence. We could give GUIDs to characters and states
but it doesn't get us very far as it doesn't permit us to re-use or
extend them in a simple way. (sure you could build an inheritance model
for characters and states but this rapidly becomes a complete ontology
language of which there are a few already available!).<br>
<br>
My gut feeling is that in the long term the Character/State model
doesn't transfer well into an open world model. I suspect this problem
may occur in other descriptive areas where the existing model specifies
noun-adjective pairs that I don't have experience of. Perhaps we could
explore this a little. Perhaps my guts need straightening out!<br>
<br>
Your thoughts greatly appreciated.<br>
<br>
Roger<br>
<br>
<pre class="moz-signature" cols="72">--

-------------------------------------
 Roger Hyam
 Technical Architect
 Taxonomic Databases Working Group
-------------------------------------
 <a class="moz-txt-link-freetext" href="http://www.tdwg.org">http://www.tdwg.org</a>
 <a class="moz-txt-link-abbreviated" href="mailto:roger at tdwg.org">roger at tdwg.org</a>
 +44 1578 722782
-------------------------------------

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