I think that in practice the potential taxon sensu Berendsohn (1995) is precisely what TDWG has primarily been addressing in recent discussion of taxon concepts. TCS can accommodate expression of other mechanisms for defining taxon concepts but does not (at least yet) do much to allow us to reason about them.

I agree that we should be aiming to create tools that wherever possible can give us an assessment of which taxon potential taxa cluster closely enough that we can treat them as a 'granule'. That is a further challenge and one that will probably largely depend on what sort of information taxonomists and others are really prepared to put into a standard like TCS.

I also note that the subject I raised in my previous e-mail was well addressed (with support on both sides) by earlier posts from Rich and Peter. My fault for responding to something while still reading.

Donald

--------------------------------------------------------------- Donald Hobern (dhobern@gbif.org) Programme Officer for Data Access and Database Interoperability Global Biodiversity Information Facility Secretariat Universitetsparken 15, DK-2100 Copenhagen, Denmark Tel: +45-35321483 Mobile: +45-28751483 Fax: +45-35321480 ---------------------------------------------------------------

-----Original Message----- From: Taxonomic Databases Working Group GUID Project [mailto:TDWG-GUID@LISTSERV.NHM.KU.EDU] On Behalf Of Nozomi Ytow Sent: 13 September 2005 13:58 To: TDWG-GUID@LISTSERV.NHM.KU.EDU Subject: Re: Different reasons for different GUIDs

Donald and all,

However there is probably insufficient benefit for us to gain from having a system where strong GUIDs are assigned to every taxon concept that any provider wishes to reference.

Exrepssion "every taxon concept" implies that we can establish identity of taxon concept. I don't think it is possible execpt potential taxon sensu Brendsohn (1995), i.e. combination of name string and publication. What we need for the benefit 3 is not GUID of 'each' taxcon cocnept but a mechanism to give an approxiamtion of a taxon concept/taxon concepts (I'm not convince how can I count taxon concepts) can be used as a granule.

JMS -- Dr. Nozomi "James" Ytow Institute of Biological Sciences / Gene research center University of Tsukuba Tsukuba, Ibaraki 305-8572 Japan