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I'm reading the book Foundations of Semantic Web Technologies. One conception really confuses me.

In the definition of a simple interpretation I, it says that IL maps the typed literals from V into the set IR of resources and LV, a particular subset of IR, called the set of literal values, containing (at least) all untyped literals from V. It seems to me that the result of mapping IL is a subset of LV. But in the diagram, which means to explain these definitions, only untyped literals map to the set LV while the mapping IL points from the typed literals to the whole resources set.

The Figure from the book

The Figure from the book

hotzst
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Monika Diao
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  • I included the linked image as part of the post. Images and code examples should always be part of the post itself instead of just links. – hotzst Jan 22 '16 at 14:02

1 Answers1

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Literals without an explicit type have the PlainLiteral type assigned to them during parsing (in OWL 2), so they are a subset of typed literals. This is compatible with OWL 1, even if at the time they wouldn't have any type at all.

Ignazio
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  • thanks for the answer. But my question was, according to the definitions, the result set of mapping _IL_ should be a subset of _LV_. But in the figure it's not the case. – Monika Diao Jan 24 '16 at 11:22
  • I believe the definition is incorrect - the set of untyped literals is not a superset of all literals, it is the set of literals whose type is not given explicitly. They constitute a different type of literals. There is a superset of all /literal forms/, meaning the set of all string representations of literal value spaces. Untyped literals appear to coincide with these literal forms, because they do not have anything specified about them except the literal form, but they actually are distinct from their own literal form. "1" is distinct from Literal("1") and from Literal("1"^^xsd:int) – Ignazio Jan 24 '16 at 11:43
  • thanks for your elaborate explanation. I think I will just consider the figure is not very accurate. In the more specific definitions for RDF interpretation and RDFS interpretation, the set LV contains untyped literal values and well-typed literal values. I would add one more set which contains all the typed literal values and intersects with _LV_ in _IR_. Sorry I don't know how to add local picture. – Monika Diao Jan 25 '16 at 11:01