An inference engine for RDF - Agfa

An inference engine for RDF
2. a mapping IEXT from IR into the powerset of IR X (IR union LV) i.e. the set
of sets of pairs with x in IR and y in IR or LV. This mapping defines the
properties of the RDF triples.
3. a mapping IS from V into IR
IEXT(x) is a set of pairs which identify the arguments for which the property is
true, i.e. a binary relational extension, called the extension of x. [RDFMS]
Informally this means that every URI represents a resource which might be a
page on the internet but not necessarily: it might as well be a physical object. A
property is a relation; this relation is defined by an extension mapping from the
property into a set. This set contains pairs where the first element of a pair
represents the subject of a triple and the second element of a pair represent the
object of a triple. With this system of extension mapping the property can be
part of its own extension without causing paradoxes. This is explained in
[RDFMS].
2.7.3. Examples
Take the triple:
:bird :color :yellow.
In the set of URI’ s there will be things like: :bird, :mammal, :color, :weight,
:yellow, :blue etc...These are part of the vocabulary V.
In the set IR of resources will be: #bird, #color etc.. i.e. resources on the internet
or elsewhere. #bird might represent e.g. the set of all birds.
There then is a mapping IEXT from #color (resources are abbreviated) to the set
{(#bird,#blue),(#bird,#yellow),(#sun,#yellow),...}
and the mapping IS from V to IR:
:bird Æ #bird, :color Æ #color, ...
The URI refers to a page on the internet where the domain IR is defined (and
thus the semantic interpretation of the URI).
2.8. RDFProlog
2.8.1. Introduction
I have defined a language called RDFProlog (by the Haskell module
RDFProlog.hs: for a sample see 5.17. Applications). This language is a concrete
syntax with RDF semantics. It forms a subset of RDF and the syntax is less
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