Foundations of the Semantic Web: Ontology Engineering

1
Foundations of the Semantic WebOntology
Engineering

• Lab 2 Untangling Ontologies
• Open World Reasoning
• Alan Rector colleagues

SETUP Download Teaching-4-01-people-tangled.
daml existentials-and-universals.damlfrom
www.cs.man.ac.uk/rector/CS646 Get the
supplementary handout Existentials Universals
2
Normalise the person hierarchystarting from
Teaching-4-01-people-tangled.daml

• Create the necessary properties, roles, and value
  types to separate sex, academic rank, age group,
  ethnicity
• There should be a separate functional property
  for each
• There should be a separate ValueType for each
• The values under the value type should be
  disjoint
• Each kind of Person should be definedDefine a
  student as a Person who attends an
  Academic_institution
• Classify and check the classification is correct
• When you are satisfied with the classification,
• Define a set of probe classes to test if the
  appropriate kinds of people are disjoint or not.

3
Add additional information

• A Subclass axiom to say thatAll academic staff
  are adults
• A new kind of Teaching_activity called Seminar
• Define a Professorial seminar as a Seminar
  given by a Professor
• Define an Assisted professorial seminar as a
  seminar given by a professor and at least one
  other member of academic staff

4
Add rules about professorial seminars

• Add a new property enrolled_in and define an ACS
  student as a student enrolled in the ACS_course
• Should enrolled in be functional? Why or why not?
  
• Add an axiom to say that all ACS students must
  take a Professorial seminar
• Define a Student taking a professorial seminar
• Classify? Is the classification correct?
• Define a probe to check if a violation of the
  axiom causes an inconsistency

5
If you have not done so already, download
existentials-and-universals.daml

• Work through the exercises on the separate sheet
• Be sure you understand how to fix the problem

6
EquivalenceAnother way to check understanding

• When preparing to change a class, it is often
  useful to create a one or more trial subclasses
  and clasify the result.
• If you think two different definitions should be
  equivalent, they should come out equivalent when
  classified, consider
• Define two different subclasses of third year
  module
• Third_year_module_try_1 complete
  Third_year_module and restriction
  (includes allValuesFrom (Lecture or Exam))
• Third_year_module_try_2 complete
  Third_year_module and not
  (restriction includes someValuesFrom Lab)
• Refer to the explanation on slides 79-82 in
  Handout 1 to modify the rest of the KB so that
  the two definitions are equivalent as shown in
  slide 81.

7
Prepare the Module hierarchy for normalisation

• Define a class ACS_course, Third_year_course, and
  CS_course
• Change the definition of ACS_module and
  Third_year module to be that they belong_to the
  ACS_course, Third_year_course, etc.
• Define Test_Module Module and restriction
  belongs-to someValuesFrom ACS_course
• Classify it. Does it come out as equal to
  ACS_module? If not why not?
• Refer to Separate handout on Definitions,
  Descriptions, Restrictions Axioms

8
Domain and Range Constraints

• Add appropriate domain and range constraints to
  all properties
• Have you made anything unsatisfiable?
• Have you made any changes in the hierarchy
• Should you have?