Thank you Roger!

I heard about DELTA and SDD seems to be very interesting! So when we are thinking about GUIDs in this context I assume you would assign a GUID on the 'contextual meaning of terms'? E.g. what open means when you describe a open umbilicus? A GUID would then direct the user to a document/ db entry which explains that ? Or would the GUID be assigned to a complete SDD description?

best regards, Robert

-----Ursprüngliche Nachricht----- Von: Taxonomic Databases Working Group GUID Project [mailto:TDWG-GUID@LISTSERV.NHM.KU.EDU]Im Auftrag von Roger Hyam Gesendet: Mittwoch, 25. Januar 2006 16:02 An: TDWG-GUID@LISTSERV.NHM.KU.EDU Betreff: Re: Characters and States and GUIDs and descriptive data

Hi Robert,

Characters and States are the building blocks of the DEscription Language for TAxonomy (DELTA). This has been around since the 1980s and is being updated as Structure of Descriptive Data (SDD) - which I am fairly ignorant on but believe has the same basic notion of characters and states but one of the SDD guys would be better talking about that.

The DELTA home page is here: http://biodiversity.bio.uno.edu/delta/ but seems to be down now. There is plenty on Google.

The SDD wiki here: http://wiki.cs.umb.edu/twiki/bin/view/SDD/WebHome (SDD also uses class in a different sense.)

I think what I was saying is that the usage of classes and states does not fit well with the use of a thesaurus like approach as the 'traditional' meaning of these things is not clear in an open world and that this may not just be a problem with DELTA style data but we may come across it in other places.

Hope this clarifies things.

Roger

Robert Huber wrote: Dear Roger,

I could not reall yunderstand what you and Kevin mean by Characters and States. From the example you gave, it appears to be like classes (character) and attributes (states) or you want to assign GUIDs to something like Thesaurus entries? But maybe I completely misunderstood what you meant..

best regards,Robert -----Ursprüngliche Nachricht----- Von: Taxonomic Databases Working Group GUID Project [mailto:TDWG-GUID@LISTSERV.NHM.KU.EDU]Im Auftrag von Roger Hyam Gesendet: Mittwoch, 25. Januar 2006 12:35 An: TDWG-GUID@LISTSERV.NHM.KU.EDU Betreff: Characters and States and GUIDs and descriptive data

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

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

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