2006-10-25 klockan 03:11 skrev James Henstridge: > On 25/10/06, Jamie McCracken <jamiemcc blueyonder co uk> wrote: > > We shouldn't need a flattened table as the two metadatatype tables would > > be properly indexed so joins would be fast (especially with sqlite) > > Really? From the description I give above, the relationships between > different metadata types form a directed graph. Taking the music > example again, consider the following set of relationship types: > 1. foo performed bar > 2. foo performed vocals on bar > 3. foo performed lead vocals on bar > > If I register that (2) is a subclass of (1) and (3) is a subclass of > (2), I want searches for relationship type (1) to pick up metadata of > types (1), (2) and (3). The RDFS Entailment Rules [1] may help inferring triples without the need for complete reasoning support. > Ideally this would be mostly invisible to users: their queries for > generic relationship types would just work, even if the metadata > extractors for particular file types produced more specialised types. > > It does mean that application authors who wish to introduce new types > of metadata need to think about how they relate to the existing types, > but that is necessary for the metadata to stay useful when doing > generic queries. Just use rdfs:subPropertyOf to a well-known type (eg. Dublin Core) and you're safe, afaics. mvrgr, Wouter [1] http://www.w3.org/TR/2004/REC-rdf-mt-20040210/#rules -- :wq mail uws xs4all nl web http://uwstopia.nl well i'm happy when it's good :: and when it's bad i cry -- the who
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