April 1999
CO230: COGNITIVE SCIENCE

QUESTION 2

Total Marks: 20 Marks

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SAMPLE STUDENT'S SOLUTIONS
for Question 2

 
(a) Describe four symbolic knowledge models.

 

 [8]
(b) Given that
  • Adam is guilty of a crime; and
  • Adam is not in jail,

state the truth values of the following propositions:
(i) Either Adam is guilty of a crime or Adam is in jail. [1]
(ii) If Adam is guilty of a crime then Adam is in jail. [1]
(iii) Adam is guilty of a crime is equivalent to Adam is in jail.

 

 [1]
(c) Given that
  • e is the symbol used to represent that the exam was easy;
  • s is the symbol used to represent that Adam studied hard;
  • p is the symbol used to represent that Adam passed the exam;
  • l is the symbol used to represent that Adam was lucky; and
  • c is the symbol used to represent that Adam was found cheating,

rewrite the following statements using symbolic representations of propositional logic:
(i) If the exam was easy or Adam studied hard, then Adam passed the exam. [1]
(ii) If the exam was not easy and Adam studied hard, then Adam passed the exam. [1]
(iii) If the exam was easy and Adam was unlucky or the exam was not easy or Adam did not study hard, then Adam would not pass the exam.

 

 [1]
(d) Given that
  • good_dog(fido) means that fido is a good dog;
  • master(ben,fido) means that ben is the master of fido;
  • location(ben,beach) means that ben is at the beach; and
  • well_trained(fido) means that fido is well trained,

rewrite the following statements using predicate representation:
(i) If ben is the master of fido and ben is at the beach, then fido is also at the beach. [2]
(ii) If ben is the master of fido, then fido will be in the same location as ben. [2]
(iii) If a dog is a good dog and has a master, then it would be in the same location as its master. [2]