This post is the second in a series about the UDC consortium international seminar in The Hague, 19-20 September, 2011.
Knowledge Organization Systems (KOSs) as hubs in the Web of Data
In a minor change of schedule, Thomas Baker from the DCMI talked about some of the practical issues with using Linked Data. Provenance data can be recorded as additional information but it is not standardised or an integral part of RDF and this is something that is a growing concern, receving attention from W3C. URI persistence and alignment remain concerns for data managment and governance.
Aligning web vocabularies
Guus Schreiber also dealt with the problem of making sure we are all talking about the same thing when we try to align our vocabularies. He called for ontologists to be modest about what they can achieve and not to try to hide the problems that occur when you try to transfer an ontology form one domain to another. Errors typically occur due to failures to notice subtle differences between domains.
Vocabulary alignment is a complex business that requires a lot of intellectual effort and multiple techniques should be used to reinforce and support each other. It is much better to map small vocabularies to large ones that can then act as “pivots”.
There is still no adequate methodology for evaluating alignments nor for mediating consensus between observers. Perhaps there should be a way of recording the strength of consensus and the presence of disagreements and alternative views.
Classification, Collaboration and the Web of Data
Dan Brickley described three types of graph – the hypertext graph of the Internet’s links between documents, the social graph of links between people, and the factual graph of links between data. Currently Linked Data is bringing together the hypertext and factual graphs, and another step would be to add in the social dimension.
He called for a focus on what the various tools can actually do, to be wary of over-evangelical ontologists, and to remember that subject classifications are strong and robust tools that are more appropriate for many types of work than ontologies.
He said that you could expect Linked Data to solve about a third of your information linking problems.