COMP318
MOCK EXAMINATIONS 2021/22
Advanced Web Technologies
SECTION A
Attempt FIVE questions from this section. Section A is worth 50 marks.
1. Provide a definition of Knowledge Graph and describe some of the properties characteris- ing them? (5 marks)
2. Explain what is meant by linked data and discuss the principles for deploying linked data on the web according to the Linked Data Effort. (5 marks)
3. Define the following statements in OWL (using its Turtle syntax). Use the names of classes and relations indicated in parentheses, with their respective namespaces, and consider each statement independently (15 marks in total):
a. All managers (ont:Manager) are employees (ont:Employee) ; (3 marks)
b. An employee (ont:Employee) has exactly one staff number (ont:hasStaffNo) associated with them; (3 marks)
c. A secretary (ont:Secretary) is an admin staff (ont:AdminStaff) and an ad- min staff is an employee (ont:Emloyee); (3 marks)
d. The name (foaf:name) of an employee is a string (xsd:string); (3 marks)
e. The relation “manages” (ont:manages) links a manager to an employee. (3 marks)
4. Describe the benefit of formulating competency questions in order to start the process of ontology modelling, and of specifying an ontology using a formal language. Clarify the meaning of formal in this context. Provide at least four examples of competency quest2 mions for a domain and task of your choice. (15 marks)
5. Define the meaning of reification and explain what it is used for. Represent the following sentence in RDF by means of reified triples (in Turtle syntax): Romeo thought that Juliet wasdead. (10 marks)
SECTION B
Attempt TWO questions from this section. Each question is worth 25 marks. Credit will be given for the best 2 answers only.
1. Consider the following RDF graph G, expressed in Turtle, where the triples have been numbered to improve readability, and rdf and rdfs are the usual namespaces. Consider the RDF graph given below:
1 :Person a rdfs:Class .
2 :Woman a rdfs:Class ;
3 rdfs:subClassOf :Person .
4 :Parent a rdfs:Class ;
5 :rdfs:subClassOf :Person .
6 :Mother :a rdfs:Class ;
7 :rdfs:subClassOf :Parent .
8 :rdfs:subClassOf :Woman .
9 :Offspring a rdfs:Class .
10 rdfs:subClassOf :Person .
11 :hasParent a rdf:Property .
12 rdfs:domain :Person .
13 rdfs:range :Parent .
14 :hasMother a rdf:Property .
15 rdfs:subPropertyOf :hasParent .
16 rdfs:range :Mother .
17 :isOffspringOf a rdf:Property .
18 rdfs:domain :Offspring ;
19 rdfs:range :Parent .
20 :Ben a :Person .
21 :hasMother :Leia .
22 :Leia a :Woman .
(a) Can you extend the graph (using only the RDF/RDFS vocabulary) to represent that :Ben and :KyloRen are the same person? If yes provide the triples representing this fact, if not motivate your answer. (4 marks)
(b) For each of the statement below, decide if the graph G entails the statement(s) given and explain why/why not? If the answer is “yes”, the statement(s) is entailed by G, then use the simple entailment rules (se1, se2) and the rdfs entailment rules (rdfs1, . . . , rdfs12) to prove that your answer is correct. If the answer is “no”, then explain, informally or formally, why this is so. A summary of the rdfs entailment rules is provided at the end of this exam paper.
i. :Mother rdfs:subClassOf :Person . (3 marks)
ii. :Leia a :Person . (3 marks)
iii. :Leia a :Parent . (3 marks)
iv. :Leia a :Woman . (3 marks)
v. :Leia :Offspring :Ben . (3 marks)
vi. :Ben :hasParent :Leia . (3 marks)
vii. :Ben :hasParent :x . (3 marks)
2. Represent the following statements in the most appropriate ontology language and explain why you choose that specific language. Please note some statements can be represented in more than one language whilst others can only be modelled using one ontology language. (5 marks)
Model the statements listed below by using the following URIs - Person, Woman, Man, Wife, Spouse, Husband, isWifeOf, isHusbandOf, paul:
a. isWifeOf and isHusbandOf are functional properties; (4 marks)
b. paulis a Man; (4 marks)
c. Wife is a Person who is not a Husband; (4 marks)
d. a Husband is someone who has at least been married once; (4 marks)
e. LifetimeSpouse is a Spouse who has one Spouse and only one Spouse; (4 marks)
3. a. An ontology alignment system A needs to be evaluated with respect to a set 120 of ref- erence correspondences (gold standard), R. A generates 45 correct correspondences and 28 incorrect ones. Discuss the different measures that can be used to evaluate the performance of an alignment system and explain what each tells us about the gener- ated alignment. Show the calculations of these measure for the alignment system A. (15 marks)
b. Given two alignment systems, A1 and A2 with the following values of p and r : p1=0.3, r1=0.7, whereas p2=0.4 and r2=0.8. Which system do you think performs best? Can you assess the performance using either only p or only r? (10 marks)