Prefixes in Trig

[Erich Bremer]

Hi,
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I am writing RDF datasets out from Jena to disk and I noticed that the 
prefix definitions are missing, meaning, all predicates are written out in 
the long URI form rather than something compact like "foaf:knows" with the 
foaf prefix defined up at the top.  The name spaces were defined the a Jena 
Model and then that model was added as a named graph to a empty dataset then 
written out to disk.  Is this expected behavior from Jena or a bug or am I 
missing something here?  - Erich
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