CIS344 The Semantic Web 2008-9: Assignment 2

CIS344 The Semantic Web 2008-9: Assignment 2
Given out Thursday Dec 11th and due in Monday Jan 22nd 2009. Answers
must be submitted electronically as a Word document or PDF. Some questions
will require you to submit additional text files - instructions to follow. There are 150 marks available on this assignment Question 1: XML [30 marks] (a) Explain the following terms in the context of XML: [8/30] i) Well-formed
ii) Valid
iii) Metadata
iv) Namespace
(b) What are some advantages of XML Schema over DTDs (Document Type
Definitions) for specifying XML vocabularies? Why is it nevertheless
important for web developers to be familiar with DTDs?
[7/30] (c) Consider the XML Schema and document shown below and answer questions
(i - iii):
[15/30]
i) Explain the difference between simple and complex types, with reference
to examples in the provided schema and document.
ii) Which (if any) entries would you expect to cause validation errors?
Justify your answer and submit a corrected version of the XML document.
iii) Explain how the schema could be modified so that: . "Medium" must be one of "Oil", "Acrylic", "Gouache", "Watercolour",
"Chalk", "Pastel", "Ink" or "Graphite";
. More than one Medium may be specified for an entry.
XML Instance of Catalogue Schema Question 2: RDF, RDF Schema and SPARQL [45 marks] (a) [9/40]
i) Explain what is meant by a statement in RDF and describe three
different ways an RDF statement can be represented.
ii) Explain the function of URIs (Universal Resource Identifiers)
in RDF statements.
iii) Explain how inheritance operates in RDF Schema with reference
to rdfs:subClassOf and rdfs:subPropertyOf. a) This question involves the use of Protégé. [16/40] The task is to to recreate the Movies ontology you produced for Lab
Exercise 2 and see how many of your property and class definitions you can
replace by using Dublin Core annotations. Start by creating a new
ontology specifying the Project Type OWL/RDF Files and the Language Profile
OWL-DL. Next, import the Simple Dublin Core elements as in Lab 6. You may
decide for example that dc:creator could replace :director.
Try and use as many of the Simple DC elements as you can, extending the
content of your original ontology if necessary. For each element, you
should explain either how you have applied it to this domain, or why you
think it is not appropriate (c) [20/40] (i) For this question you will be using the Protégé implementation
of the SPARQL query language. The data source will be the RDF version of
the Periodic Table of the Elements. This is linked to from Leigh Dodds'
SPARQL tutorial, which you will have worked through for Lab Exercise 5.
You may need to consult the updated instructions for that exercise. Construct SPARQL queries and run them in the SPARQL Query panel to extract
the following information: 1. A table of all elements in the periodic table giving their name,
symbol, atomic number and atomic weight. Give the query only in
your answer, not the result.
2. The first 10 entries in the table from (1) above in alphabetical
order of names. Give the full query and the names of the
elements in the result.
3. The elements with the 10 highest atomic weights below 200. Give
the query and the names and atomic weights of the elements in
your answer.
4. All elements with colour "metallic" or "metallic grey". See if
you can find two different ways to express the query. Give the
queries and the names and colours of the elements in your
answer. (ii) Comment on Protégé's implementation of SPARQL. Are there any
ways you think it could be improved?
Question 3: Logic and Reasoning [40 marks] (a) According to Antoniou and van Harmelen's Semantic Web Primer, one of
the main requirements for an ontology language is "efficient reasoning
support". What is meant by reasoning support, and what are some uses for
reasoning when constructing and/or querying ontologies or knowledge bases
for the Semantic Web? [8/40]
(b) Show using truth tables whether: [16/40] i) (P & Q) > R implies (P v Q) > R ;
ii) ¬(P & Q) is equivalent to ¬P v ¬Q (c) The following is an excerpt from an OWL document, coded in RDF/XML. i) Explain in your own words the use of the attributes rdf:ID and
rdf:resource, and of subClassOf with Restriction, and express the
content both in ordinary English and as a formula of predicate
calculus.
ii) Explain what is meant by transitive properties. Can the property
is-part-of be interpreted as a transitive property in the example
below? Justify your answer.
[16/40]









(Antoniou and van Harmelen, A Semantic Web Primer, 2004/2008.)
Question 4: Applications [35 marks] Compare the following statements: "The Semantic Web will bring structure to the meaningful content of
Web pages, creating an environment where software agents roaming from
page to page can readily carry out sophisticated tasks for users".
From "The Semantic Web" by Berners-Lee, Hendler and Lassila, in
Scientific American, 2001. "Because we haven't yet delivered large-scale, agent-based mediation,
some commentators argue that the Semantic Web has failed to deliver".
From "The Semantic Web Revisited" by Shadbolt, Hall and Berners-Lee,
in IEEE Intelligent Systems, 2006. Do you think it reasonable to say that the Semantic Web has failed to meet
expectations or should it be regarded as a work-in-progress which has
already a degree of success? If the latter, what factors in addition to
the "infrastructure" of Semantic Web languages and ontologies will be
critical to the success of the enterprise? Justify your answers with
reference to existing or planned applications as described in the Semantic
Web Primer or elsewhere. You should not write more than about 800 - 1000
words. -----------------------





XML Schema: "Catalogue"


JMW Turner
Oil
Canvas
National Gallery
London



David Hockney
Canvas
Acrylic
Unknown



Rembrandt
Chalk
Paper
National Gallery of Art



Jasper John
Pastel
Graphite
Paper
National Gallery of Art
Washington

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