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This slide show
a RDF graph consisting of a single triple. However this is not a valid RDF
graph. Why not?
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Because all
labels in a valid RDF graph need to have a ‘ namespace ’.
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A namespace is a
URI (Universal Resource Indicator) like the URI in the upper part of the
slide:
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http://www.daml.or/2001/01/gedcom/gedcom#
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Often we will
want to abbreviate those namespaces e.g. gd is the abbreviation for the URI
above.
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gd:zoon(def:Frank,
def:Christine)
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is then a valid
triple. ‘ def ’ might be the abbreviation of a namespace of my own
(everybody is entitled to create (unique) namespaces).
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When no
namespace is indicated, the default namespace applies. In the exemple of the
slide show, namespaces were omitted for reasons of clarity.
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What is the
importance of namespaces?
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A namespace
indicates the origin of a label. Eventually the trust system might reject a
triple because a label from a non-trusted site is present.
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Also the notions
occurring in the triple like ‘ sun ’, ‘ Frank ’,
‘ Christine ’ must be defined in the corresponding namespace.
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Note that the
origin of a triple and the origins of its labels are not necessarily the
same.
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This system thus
plays a role in the verifiability of a triple.
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